JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 50 NUMBER 1/2 2002 JANUARY/FEBRUARY CONTENT President’s Message...... Garry Margolis 3 PAPERS Fourth-Order Symmetrical Band-Pass Loudspeaker Systems ...... Grzegorz P.Matusiak and Andrzej B. Dobrucki 4 The analysis of fourth-order band-pass loudspeaker systems based on the well-known Thiele, Small, and Benson theory is presented using a reactance transformation method. By comparing the acoustic analog circuit with the transfer function obtained from the reactance transformation, the results allow the symmetry condition to be determined. The resulting system has advantages over closed-box and vented-box high-pass systems in terms of power and efficiency. Maximizing Performance from Loudspeaker Ports ...... Alex Salvatti, Allan Devantier, and Doug J. Button 19 The low-frequency performance of a loudspeaker is significantly enhanced by the use of tapered ports, but there are numerous trade-offs involving the size of the port and the input and output tapers. Design issues include the effectiveness of heat transfer, amount of turbulence created, air velocity, smoothness of the taper, symmetry of the two tapers, effective mass in the port, and the contribution to the frequency response. Suggested design rules are based on extensive empirical studies. ENGINEERING REPORTS Wavetable Matching of Inharmonic String Tones ...... Clifford So and Andrew B. Horner 46 A new wavetable matching technique for inharmonic music tones, such as a violin with vibrato, shows good spectral matching and adequate frequency resolution. Confirmation with listening tests significantly improves the perceived matching but degrades performance on harmonic trumpet tones compared to simple wavetable matching. The new method offers more than a three-fold improvement over additive synthesis for these cases, but for harmonic tones the original matching technique should be used. Localization of Virtual Sound as a Function of Head-Related Impulse Response Duration ...... Melis A. Senova, Ken I. McAnally, and Russell L. Martin 57 The localization accuracy of subjects using headphones was determined as a function of the duration of the head-related impulse response. Unlike previous studies, there was a gradual decrease in accuracy starting at 10 ms and becoming drastically worse at about 0.5 ms. Durations of more than 10 ms result in performance indistinguishable from free-field localization. Shorter durations are equivalent to smoothing the frequency response and thereby removing the fine detail unique to each subject’s own ears. CORRECTIONS Correction to “Multitone Testing of Sound System Components—Some Results and Conclusions, Part 1: History and Theory” ...... Eugene Czerwinski, Alexander Voishvillo, Sergei Alexandrov, and Alexander Terekhov 66 STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 67 ATM networking; acoustics measurement; EMC; IEEE1394 networks; network and file transfer Call for Comment on DRAFT AES47-xxxx, DRAFT AES standard on digital audio digital input-output interfacing transmission of digital audio over asynchronous transfer mode (ATM) networks...... 67 Call for Comment on REAFFIRMATION of AES18-1996, AES recommended practice for digital audio engineering — Format for the user data channel of the AES digital audio interface...... 67 Call for Comment on REAFFIRMATION of AES20-1996, AES recommended practice for professional audio — Subjective evaluation of loudspeakers...... 68 Call for Comment on REAFFIRMATION of AES27-1996, AES recommended practice for forensic purposes — Managing recorded audio materials intended for examination...... 68 Call for Comment on WITHDRAWAL of AES15-1991, AES recommended practice for sound- reinforcement systems — Communications interface (PA-422) ...... 68 FEATURES Audible Alarms for the Hearing Impaired ...... John Vanderkooy 73 Education News...... 81 113th Convention, Los Angeles, Call for Papers ...... 100 DEPARTMENTS News of the Sections ...... 82 Advertiser Internet Directory...... 97 Upcoming Meetings ...... 87 In Memoriam ...... 98 Sound Track...... 88 AES Special Publications ...... 101 New Products and Developments...... 90 Sections Contacts Directory ...... 106 Available Literature ...... 92 AES Conventions and Conferences ...... 112 Membership Information...... 93 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 50 NUMBER 3 2002 MARCH

CONTENT

PAPERS Effect Design, Part 3 Oscillators: Sinusoidal and Pseudonoise...... Jon Dattorro 115 This is the third of a three-part series that provides a tutorial reference for those signal processing algorithms that are of particular interest to music. In this part, the issues of low-frequency sinusoidal oscillators and sonically pleasant pseudorandom noise generators are reviewed, compared, and analyzed. Both topics actually have deep issues even though the signal definitions are simple. The historical background, pertinent references, and appendices provide the reader with a comprehensive foundation in these subjects. Reproducing Low-Pitched Signals through Small Loudspeakers ...... Erik Larsen and Ronald M. Aarts 147 Because small-volume loudspeakers are unable to reproduce low frequencies, alternative methods can be used to create the illusion of those frequencies by taking advantage of a phantom-pitch phenomenon—the perception of a fundamental when only its harmonics are present. The low frequencies below the loudspeaker cutoff point are extracted from the wide-band signal, nonlinearly processed, filtered again, and finally injected into the path of the main signals. Listeners prefer this artificial bass in comparison to flat reproduction through a small loudspeaker. A particular implementation of phantom pitch is illustrated. Generating Source Streams for Extralinguistic Utterances...... Eduardo Reck Miranda 165 Most speech-synthesis systems do not provide a mechanism for creating nonspeechlike signals, such as sounds like boom, meow, gurgles, and genetic vocal noises. To avoid the mechanical-sounding attributes of other approaches, the author adapts a cellular automata control of the spectral parameters. The array of parameters is updated according to a set of rules to create transitions between states using the values of the neighboring cells as input parameters. While this approach works well to create natural sounds, there is insufficient knowledge about how to create an imagined sound.

ENGINEERING REPORTS Estimating the Loudspeaker Response when the Vent Output is Delayed...... Neville Thiele 173 A new wavetable-matching technique for inharmonic music tones, such as a violin with vibrato, shows good spectral matching and adequate frequency resolution. Confirmation with listening tests significantly improves the perceived matching but degrades performance on harmonic trumpet tones compared to simple wavetable matching. The new method offers more than a three-fold improvement over additive synthesis for these cases, but for harmonic tones the original matching technique should be used.

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 176 Audio connectors

FEATURES 112th Convention Preview, Munich...... 178 Calendar...... 180 Exhibitors...... 181 Exhibitor Previews ...... 184 113th Convention, Los Angeles, Call for Workshops Participants ...... 206

DEPARTMENTS News of the Sections ...... 201 In Memoriam ...... 212 Upcoming Meetings ...... 203 AES Special Publications ...... 213 Sound Track...... 205 Sections Contacts Directory ...... 218 Membership Information...... 207 AES Conventions and Conferences ...... 224 Advertiser Internet Directory...... 209 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 50 NUMBER 4 2002 APRIL

CONTENT

PAPERS Restoration and Enhancement of Solo Guitar Recordings Based on Sound Source Modeling ...... Paulo A. A. Esquef, Vesa Välimäki, and Matti Karjalainen 227 By combining techniques for music synthesis and analysis, the authors demonstrated that the restoration of guitar recordings had been corrupted by added noise and limited spectral bandwidth. During the analysis phase the parameters of the synthesis model were extracted and then used to define the synthesis model, which is able to produce a simulation without noise or spectral limits. The initial corruption and the musical complexity limit the accuracy of the parameter extraction. The results of this work should be considered a pilot study. On the Quality of Hearing One’s Own Voice ...... Ronald Appel and John G. Beerends 237 Evaluating the quality of sound reproduction in a telecommunications environment over long distances is unique and unrelated to the classical problem of reproduction quality. Specifically, the experiments attempt to calibrate the acceptable quality level for the listener’s own voice through the side channel when it has been delayed and distorted. The proposed model represents degradation as a single number to predict the subjective experience of comfort while talking and listening to one’s own voice. Comparison of Different Impulse Response Measurement Techniques ...... Guy-Bart Stan, Jean-Jacques Embrechts, and Dominique Archambeau 249 Although the impulse response of a linear, time-invariant system is mathematically defined, the choice of empirical methods strongly influences the results when applied to a real room with noise and other imperfections. The authors explored the relationship between the environment under test and four different approaches: maximum-length sequences, inverse repeated sequences, time-stretched pulses, and SineSweep. Recommended choices are suggested based on noise level, accuracy, and calibration effort.

ENGINEERING REPORTS Variability in the Headphone-to-Ear-Canal Transfer Function ...... Ken I. McAnally and Russell L. Martin 263 The quality of virtual auditory space simulation using headphones is determined, in part, by the accuracy of the head-related transfer function that models the influence of the head and pinna as a function of sound location. A potential problem with the resulting filters is that the transfer function is influenced by the variability of listener headphone placement, which might change the localization accuracy. After careful study the authors concluded that the variability is not sufficient to significantly influence perception.

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 267 Call for comment communications; digital interfacing; preservation and restoration

FEATURES 21st Conference Preview, St. Petersburg, Russia...... 274 Calendar...... 276 Program...... 278 Registration Form ...... 289 22nd Conference Preview, Espoo, Finland...... 290 Calendar...... 292 Program...... 293 Registration Form ...... 301 Updates and Corrections to the 2001/2002 International Sections Directory...... 302

DEPARTMENTS Review of Acoustical Patents...... 271 Membership Information...... 311 News of the Sections ...... 303 Advertiser Internet Directory...... 312 Sound Track...... 307 AES Special Publications ...... 315 New Products and Developments...... 308 In Memoriam ...... 320 Upcoming Meetings ...... 310 Sections Contacts Directory ...... 322 Available Literature ...... 310 AES Conventions and Conferences ...... 328 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 50 NUMBER 5 2002 MAY CONTENT PAPERS A Model of Loudness Applicable to Time-Varying Sounds ...... Brian R. Glasberg and Brian C. J. Moore 331 A previous model for computing the subjective loudness of steady-state sounds from their spectra has been extended to include time variations. After filtering the input signal to mimic the frequency response of the outer and middle ear, a fast Fourier transform (FFT) of the resulting signal is then used to compute an instantaneous loudness. The overall loudness uses attack and release times to convert the instantaneous loudness to the subjective experience of the listeners. The model gives good results with modulated signals over a wide range of rates. Perception of Reverberation Time in Small Listening Rooms...... T.I. Niaounakis and W. J. Davies 343 Spatial parameters, such as reverberation time, are typically used for large spaces and have not been extensively applied in a small room. This study determined that listeners’ sensitivity to changes in reverberation time was on the order of 40 ms. Two methods were used: changing absorption in a real space and simulating changes from a dummy head with delay headphone reproduction.

ENGINEERING REPORTS An IIR Synthesis Method for Plucked-String Instruments with Embedded Portamento ...... Alvin W.Y. Su, Wei-Chen Chang, and Rei-Wen Wang 351 The normal wavetable technique for synthesizing the portamento of plucked-string instruments, such as the ancient Chinese San-Sien, fails because of the wide frequency range. A new approach, which uses a wavetable to drive an infinite-impulse-response (IIR) filter whose coefficients have been modeled as a neural network training algorithm, provides accurate synthesis of these unusual sounds. The method assumes that the sounds are quasi-periodic, which also makes the method appropriate for certain wind instruments. Signal processing requirements are not particularly problematic. Dipole Loudspeaker Response in Listening Rooms ...... James M. Kates 363 A dipole loudspeaker, which radiates sound energy from both the front and rear surfaces, appears as a velocity source, whereas the conventional monopole loudspeaker appears as a pressure source. Although the dipole loudspeaker can provide better auditory localization accuracy, it is more sensitive to room placement and angular orientation. Using a two-dimensional simulation, the author explores the importance of room response and coloration of the reproduced sounds.

LETTERS TO THE EDITOR Comments on In Memoriam...... Roy Allison 375

CORRECTIONS Correction to Content Page ...... 375

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 376 Digital audio measurements; loudspeaker modeling; audio connections

FEATURES Managing Change: The Challenge of Rights Management in the New Millennium ...... Keith Hill 380 Audio for Games...... Martin Wilde 392 114th Convention, Amsterdam, Call for Papers ...... 417

DEPARTMENTS News of the Sections ...... 397 Advertiser Internet Directory...... 410 Upcoming Meetings ...... 401 AES Special Publications ...... 411 Sound Track...... 402 In Memoriam ...... 416 New Products and Developments...... 404 Sections Contacts Directory ...... 418 Available Literature ...... 407 AES Conventions and Conferences ...... 424 Membership Information...... 408 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 50 NUMBER 6 2002 JUNE

CONTENT

PAPERS Magnetic Circuit Design Methodologies for Dual-Coil Transducers...... Douglas J. Button 427 Renewed interest in the old idea of using dual voice coils, axial not concentric, leads to reconsidering this architectural approach to modern consumer and professional applications. The author reviews and analyzes numerous design tradeoffs in magnetic materials, magnetic geometries, and voice-coil topologies in order to illustrate potential advantages of this approach to driver design. Advantages, when compared to single-coil drivers, include weight, power handling, power compression, and distortion. An additional shorted coil between the two drive coils acts as dynamic braking. Loudspeaker Voice-Coil Inductance Losses: Circuit Models, Parameter Estimation, and Effect on Frequency Response ...... W. Marshall Leach, Jr. 442 Modeling of the losses in a loudspeaker voice coil is not straightforward, even when the series resistance is separated from the inductor and when both are viewed as discrete elements. The parametric representation of the inductor must include a frequency-dependent resistance and inductance in parallel. A SPICE analysis is compared to experimental data in order to validate the proposed parameters that incorporate the frequency-dependent impedance and phase. Similarity Evaluation of Room Acoustic Impulse Responses: Visual and Auditory Impressions ..Akira Omoto, Chizuko Hiratsuka, Hiroaki Fujita, Tetsuhiko Fukushima, Masataka Nakahara, and Kyoji Fujiwara 451 A comparison between the original impulse response of a room and its simulation must be made in order to evaluate the quality of the simulation. However, this leads to the dilemma of using a listening or visual method for judging similarity. In this study a single frequency band was deliberately changed in amplitude to create a controlled difference between the two cases, which then served as a basis for evaluating the two methods of judgment. Results show a very high level of correlation between visual inspection and subjective listening. A New Nonstationary Test Procedure for Improved Loudspeaker Fault Detection ...... Manuel Davy and Christian Doncarli 458 Manufacturing efficiencies require a general method to automatically detect production faults without any prior information about the nature of such faults. The authors propose a method that uses a mixture of four chirped signals covering the complete frequency range as a brief signal that mimics a speech or musiclike stimulus. The method was evaluated by comparing aged loudspeakers with varying levels of fatigue with new loudspeakers. The approach does not require a special environment or a model of the loudspeaker or its failure modes. Yet the results are accurate.

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 470 Radio traffic data; preservation and restoration; analog recording; transfer technologies

FEATURES 112th Convention Report, Munich...... 474 Exhibitors...... 492 Program...... 495 Updates and Corrections to Review of Society’s Sustaining Members ...... 526 114th Convention, Amsterdam, Call for Papers ...... 535

DEPARTMENTS Review of Acoustical Patents...... 472 Available Literature ...... 534 Upcoming Meetings ...... 526 Membership Information...... 536 News of the Sections ...... 527 In Memoriam ...... 537 Sound Track...... 531 Sections Contacts Directory ...... 538 New Products and Developments...... 532 AES Conventions and Conferences ...... 544 Advertiser Internet Directory...... 534 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 50 NUMBER 7/8 2002 JULY/AUGUST

CONTENT

PAPERS On the Design and Efficiency of Class A, B, AB, G, and H Audio Power Amplifier Output Stages ...... Rosalfonso Bortoni, Sidnei Noceti Filho, and Rui Seara 547 Audio power amplifiers are usually analyzed with resistive loads with an added compensation factor for nominally reactive loads of real loudspeakers. The current study examines amplifiers of class A, B, AB, G, and H under conditions of reactive loads with sine wave to determine the true stress on the power stage. By using a more exact method, the economic inefficiency of the older approximation is avoided. A procedure for designing and assessing output stages is also proposed. Requirements for Low-Frequency Sound Reproduction, Part I:The Audibility of Changes in Passband Amplitude Ripple and Lower System Cutoff Frequency and Slope...... S¿ren Bech 564 The low-frequency loudspeaker in a 5.1 system has been investigated in terms of perception of its frequency cutoff, slope of the cutoff, and passband ripple. The cutoff frequency has a very significant effect on the subjective sense of “lower bass,” but the cutoff slope was found not to be significant. The audibility of ripple depends on the nature of the audio signal. Results were consistent in both an anechoic test procedure and a headphone simulation of that environment.

ENGINEERING REPORTS Requirements for Low-Frequency Sound Reproduction, Part II: Generation of Stimuli and Listening System Equalization...... Jan Abildgaard Pedersen and Aki Mäkivirta 581 Using headphones to simulate the perception of loudspeakers in an anechoic chamber is easier and more efficient, but it requires signal processing to produce the equivalent sound signals. This study describes the algorithms used in a previous study of the low-frequency channel loudspeaker. Signals were pre-equalized with added nonlinear processing based on head-related transfer measurements made in an anechoic chamber with an actual loudspeaker. Reconstruction Method for Missing or Damaged Long Portions in Audio Signal ...... Ismo Kauppinen and Jyrki Kauppinen 594 Using a reconstruction method described previously, the authors demonstrate an algorithm that replaces gaps of up to several thousand samples with synthesized audio. Using three different types of music, the extrapolation method was able to reconstruct successfully the missing audio, so that listeners could not hear the difference between it and the original. The method was applied in practice to correct scratches from badly damaged recordings, but it can also work with any kind of impulse noise in real time.

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 603 Acoustics and sound-source modeling Call for Comment on REVISION of AES10-1991(r1997), AES recommended practice for digital audio engineering—Format for the user data channel of the AES digital audio interface...... 603

FEATURES 113th Convention Preview, Los Angeles ...... 606 Calendar...... 608 Exhibitors...... 610 Exhibit Previews...... 614 Updates and Corrections to the 2001/2002 International Sections Directory...... 636 23rd Conference, Copenhagen, Call for Papers...... 641

DEPARTMENTS News of the Sections ...... 629 Membership Information...... 637 Upcoming Meetings ...... 634 In Memoriam ...... 639 Sound Track...... 635 Sections Contacts Directory ...... 642 Advertiser Internet Directory...... 635 AES Conventions and Conferences ...... 648 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 50 NUMBER 9 2002 SEPTEMBER

CONTENT

PAPERS Spatial Quality Evaluation for Reproduced Sound: Terminology, Meaning, and a Scene-Based Paradigm...... Francis Rumsey 651 Improving the quality of spatial reproduction suffers because of an incomplete definition of the subjective attributes that contribute to the experience of space. Moreover, the lexicon of spatial concepts is often ambiguous and ill defined. This review of existing standards and research highlights the problem of extending controlled laboratory results to real applications of sound reproduction, especially when different goals, such as evaluating equipment versus modeling human perception, are involved. Describing Telephone Speech Codec Quality Degradations by Means of Impairment Factors ...... Sebastian Möller and Jens Berger 667 Predicting the quality of a telephone channel with multiple sources of degradations from a variety of codecs is a labor-intensive activity that must be repeated for each condition. The authors propose a perceptually based model that produces a single equipment impairment index as a way to approximate the degradation contributed by a particular device. Preliminary results suggest that the proposed algorithm, based on auditory tests, provides insight into the expected results. Low-Crest-Factor Multitone Test Signals for Audio Testing ...... Alexander Potchinkov 681 Test signals composed of a large number of discrete frequencies offer the advantage of high-speed measurements and the ability to simulate the spectrum of natural audio under controlled conditions. However, selecting the phase relationship to minimize the crest factor becomes a special problem. Minimizing the crest factor increases the signal power for a fixed clipping level. This paper shows that ad hoc schemes are useful but often inferior to a formal optimization, and that they should not be used if enough compute time is available for a theoretical optimization.

ENGINEERING REPORTS About the 10-dB Switch of a Condenser Microphone in Audio Frequency Circuits ...... Holger Pastillé and Martin Ochmann 695 Because high sound levels can overload the input preamplifier of a condenser microphone, one of two techniques is typically used to reduce the level: switching a parallel capacitor across the microphone or reducing the polarizing voltage. Both techniques reduce the signal level but with very different effects on nonlinearity. This paper explores both the mathematical and practical implications of level reduction, with a warning to users faced with an overload condition.

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 703 Internet communications update; synchronization; forensic audio; microphone measurement; listening tests; audio connections Survey: Fiber Optic Connectors ...... insert

FEATURES 21st Conference Report, St. Petersburg ...... 710 23rd Conference, Copenhagen, Call for Papers...... 737 24th Conference, Banff, Call for Contributions...... 738

DEPARTMENTS Review of Acoustical Patents...... 708 Membership Information...... 732 News of the Sections ...... 718 Advertiser Internet Directory...... 734 Sound Track...... 725 In Memoriam ...... 736 Upcoming Meetings ...... 726 AES Special Publications ...... 741 New Products and Developments...... 727 Sections Contacts Directory ...... 746 Available Literature ...... 731 AES Conventions and Conferences ...... 752 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 50 NUMBER 10 2002 OCTOBER

CONTENT

PAPERS Perceptual Evaluation of Speech Quality (PESQ): The New ITU Standard for End-to-End Speech Quality Assessment Part I—Time-Delay Compensation...... Antony W. Rix, Michael P.Hollier, Andries P.Hekstra, and John G. Beerends 755 Creating a model for the subjective speech quality in modern telephone networks, which includes voice- over Internet, presents special problems because of time-varying delay during transmission. Including delay compensation in the evaluation algorithm is required in order to match subjective judgments. The paper explores the numerous origins of variable delay and its perceptual influence on subjective quality. Delay can only be considered to be constant over relatively short intervals. Perceptual Evaluation of Speech Quality (PESQ):The New ITU Standard for End-to-End Speech Quality Assessment Part II—Psychoacoustic Model...... John G. Beerends, Andries P.Hekstra, Antony W. Rix, and Michael P.Hollier 765 Using delay compensation, as described in Part I above, the authors present a full psychoacoustic model for the perceptual evaluation of speech quality in telephone systems to predict the end-to-end judgment of subjective degradation. The final quality score is a combination of many independent measures. Although extensive empirical testing of the cognitive model showed that it provided a much better measure of degradation than previous approaches, additional factors are yet to be included in the model. Improved Microphone Array Configurations for Auralization of Sound Fields by Wave-Field Synthesis...... Edo Hulsebos, Diemer de Vries, and Emmanuelle Bourdillat 779 In order to provide accurate auralization when reproducing an acoustic field in a large space, significant amounts of impulse response data are required. The paper investigates and compares three classes of microphone array configurations: linear, cross, and circular. The proposed circular configuration, the basis for wave-field synthesis, provides better spatial reconstruction over a wider area because it avoids diffraction effects present at the end points in the other configurations. Crossover Systems in Digital Loudspeakers ...... S. C. Busbridge, Y.Huang, and P.A. Fryer 791 Implementing a crossover network for a digital loudspeaker allows the individual binary currents to be filtered into two spectral channels because the operations of digital-to-analog conversion and filtering can be interchanged. The paper explores a mathematical simulation of a proposed digital loudspeaker using a separate voice coil for each bit. Actual measurements from an experimental system are then used to support the results.

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 799 Digital interfacing; digital libraries; loudspeaker modeling and measurement; high-performance serial bus

FEATURES 22nd Conference Report, Espoo ...... 804 New Officers 2002/2003...... 814 Review of Society’s Sustaining Members ...... 816 Education News...... 838 24th Conference, Banff, Call for Contributions...... 851

DEPARTMENTS News of the Sections ...... 839 Advertiser Internet Directory...... 849 Sound Track...... 844 In Memoriam ...... 850 Upcoming Meetings ...... 844 AES Special Publications ...... 853 New Products and Developments...... 845 Sections Contacts Directory ...... 858 Available Literature ...... 847 AES Conventions and Conferences ...... 864 Membership Information...... 848 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 50 NUMBER 11 2002 NOVEMBER

CONTENT

PAPERS Estimation of Modal Decay Parameters from Noisy Response Measurements ...... Matti Karjalainen, Poju Antsalo, Aki Mäkivirta, Timo Peltonen, and Vesa Välimäki 867 Estimating decay parameters, such as room reverberation or string decay of musical instruments, becomes more inaccurate as the noise level increases if that noise is not also included in the parametric model. A new method based on nonlinear optimization of a linear model with additive noise is demonstrated as being more accurate than the traditional approaches, especially at extreme noise conditions. Several practical examples illustrate the utility of the proposed method. On the Use of TimeÐFrequency Reassignment in Additive Sound Modeling ...... Kelly Fitz and Lippold Haken 879 The conventional short-time spectral analysis is unable to parameterize signals that have both narrow- band components combined with transients because of the nature of the timeÐfrequency definition. Moreover, a single musical partial, which often has time-varying amplitude and frequency envelopes, does not appear as a single component in the classical linear analysis approach. By reassigning energy components, temporal smear is greatly reduced because unreliable data points can be removed from the representation. Several examples illustrate the ability to reconstruct abrupt onset square waves. Scalable Multichannel Coding with HRFT Enhancement for DVD and Virtual Sound Systems ...... M. O. J. Hawksford 894 Using the perceptual properties embedded in the head-related transfer functions of a normal listener, a standard five- or six-channel audio source can be transformed to feed additional loudspeakers, perhaps as many as 18. The proposed system enhances image stability by optimizing the correct ear signals at the listener’s location. The approach improves spatial resolution over a wider area while retaining backward compatibility with an unprocessed reproduction environment. Two-to-Five Channel Sound Processing...... R. Irwan and Ronald M. Aarts 914 In order to reproduce two-channel audio sources in a surround listening environment, the authors evaluated a proposed processing system based on decoding the principle directional component using correlation techniques. By parameterizing direction a stable center channel was created. Moreover, the synthesized ambiance for the sides does not degrade image stability.

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 927 New Internet facilities; preservation of recordings; storage and handling; audio connectors; grounding and shielding; file exchange

FEATURES 113th Convention Report, Los Angeles...... 934 Exhibitors...... 950 Program...... 954 Bluetooth and Wireless Networking—A Primer for Audio Engineers...... 979 11th Tokyo Regional Convention, Call for Papers ...... 1001

DEPARTMENTS News of the Sections ...... 985 Membership Information...... 993 Sound Track...... 989 Advertiser Internet Directory...... 999 Upcoming Meetings ...... 990 In Memoriam ...... 1000 New Products and Developments...... 990 Sections Contacts Directory ...... 1002 Available Literature ...... 992 AES Conventions and Conferences ...... 1008 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 50 NUMBER 12 2002 DECEMBER

CONTENT President’s Message...... Kees Immink 1011 PAPERS Frequency-Zooming ARMA Modeling of Resonant and Reverberant Systems ...... Matti Karjalainen, Paulo A. A. Esquef, Poju Antsalo, Aki Mäkivirta, and Vesa Välimäki 1012 Complex linear, time-invariant modeling of a system with high modal density is extremely difficult, for example, room reverberation. A frequency-zooming method based on an extension of previous techniques is explored for high-resolution modeling of systems with many poles and zeros. Such models can be used not only to generate accurate time responses, but also to serve as the basis for inverse filtering and equalization. Passive All-Pass Crossover System of Order 3 (Low Pass) + 5 (High Pass), Incorporating Driver Parameters...... Neville Thiele 1030 A third-order low-pass channel combined with a fifth-order high-pass channel can be designed to produce an overall all-pass crossover between the two channels. Because the two channels are approximately in phase over the crossover region, the approach is more tolerant to variations in driver parameters and physical offsets in the cabinet. Although the approach adds a modest cost, the benefits appear to justify the incremental complexity. Experimental Evidence of Cooperation Phenomena Application to a Loudspeaker with Rub ...... Fernando Bolaños 1039 Unlike a linear system, which preserves the frequency integrity of each signal component, a nonlinear system can shift energy from one spectral component to another. Although the theoretical basis of energy cooperation is well known, the author empirically demonstrates the phenomena in an electroacoustic experiment involving a voice coil with friction. When random noise is added to a sine wave, the nonlinear process moves energy from the noise to the sine frequency. This is analogous to the way that a limit-cycle oscillator converts the dc of the power supply into a spectral component. ENGINEERING REPORTS Iterative Combinatorial Basis Spectra in Wavetable Matching ...... Alan Ng and Andrew Horner 1054 As an alternative to the combinatorial approach to wavetable synthesis, an iterative method is proposed to increase the computational efficiency while achieving a comparable effectiveness. The algorithm was evaluated using tones from the trumpet, tenor voice, and Chinese pipa (a plucked stringed instrument). The number of wavetables dramatically influenced the rms error. In addition, subjective listening tests determined the degree to which the synthesized signal was equivalent to the original. STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 1064 Calls for Comment: MADI revision, life expectancy of CD-ROM; Internet audio; audio metadata FEATURES Moving Digital Audio, Part 1...... 1068 2002/2003 AES International Sections Directory...... 1076 Education News...... 1106 Call for Nominations for Board of Governors ...... 1113 Call for Awards Nominations...... 1114 11th Tokyo Regional Convention, Call for Papers...... 1124 115th Convention, New York, Call for Papers ...... 1125 114th Convention, Amsterdam, Call for Workshops Participants ...... 1126 Bylaws: Audio Engineering Society, Inc...... 1127 Index to Volume 50...... 1132 DEPARTMENTS News of the Sections ...... 1101 AES Annual Report ...... 1115 Sound Track...... 1108 Membership Information...... 1116 New Products and Developments...... 1109 Advertiser Internet Directory...... 1119 Upcoming Meetings ...... 1110 In Memoriam ...... 1120 Available Literature ...... 1111 AES Conventions and Conferences ...... 1144 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 51 NUMBER 1/2 2003 JANUARY/FEBRUARY CONTENT

PAPERS Analysis of Traditional and Reverberation-Reducing Methods of Room Equalization ...... Louis D. Fielder 3 Unlike the traditional approach to room equalization, which compensates for the steady-state spectral effects, a true equalization method will become a dereverberator. Such an approach simultaneously removes the acoustic properties of the reproduction environment in both the frequency and time domains. It is a very difficult problem. Although the proposed solution proves to be impractical when employed in a real application, the analysis illuminates several critical criteria for evaluating any solution. New psychoacoustic metrics successfully predicted those degradations that made the system unacceptable. Kautz Filters and Generalized Frequency Resolution:Theory and Audio Applications ...... Tuomas Paatero and Matti Karjalainen 27 Most audio signal processing filters use a basic building block containing a delay or a pole, but other choices of orthonormal functions include the use of an all-pass block. When using this type of block, the resulting structures, called Kautz filters, readily allow frequency warping. Although this approach has been overshadowed by the more traditional methods, the authors show that lower order filters are needed when applied to loudspeaker equalization, room response modeling, and guitar body acoustics. The design phase is more complex, but there is no additional computation load at run time. Horn Acoustics: Calculation through the Horn Cutoff Frequency...... Peter A. Fryer 45 The author reconsiders the mathematical approach to analyzing exponential horn loudspeakers above and below the cutoff frequency. This work provides a more solid foundation for the simplified methods of partitioning the mathematics into two regions with different assumptions in each one. By introducing a tiny amount of acoustic loss into the model, the mathematics no longer break down when traversing the transition region at cutoff. The results agree with measured data. Modified Discrete Cosine Transform—Its Implications for Audio Coding and Error Concealment ...... Ye Wang and Miikka Vilermo 52 This study of the modified discrete cosine transform (MDCT) explores the implications of audio coding and error concealment from the perspective of Fourier frequency analysis. Subjective coding quality and the tolerance to missing or repeated compressed data blocks often produce contradictory requirements in real applications. Tradeoffs involve the selection of window-sized crossfade transitions between blocks and perception of uncancelled alias components. CORRECTIONS Correction to: “On the Use of TimeÐFrequency Reassignment in Additive Sound Modeling” ...... Kelly Fitz and Lippold Haken 62 STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 63 MADI; loudspeaker components; peak flutter; tape storage; CD-ROM life; loudspeaker polar data; digi- tal input-output interfacing; digital synchronization; media storage and handling; library and archive systems; forensic audio; audio connectors; shielding and EMC; audio over IEEE 1394 FEATURES 114th Convention Preview, Amsterdam...... 76 Calendar...... 78 Exhibitors...... 79 Exhibit Previews...... 81 Virtual and Synthetic Audio ...... 93 115th Convention, New York, Call for Papers...... 112 DEPARTMENTS News of the Sections ...... 99 Advertiser Internet Directory...... 109 Upcoming Meetings ...... 104 In Memoriam ...... 111 Sound Track...... 105 Sections Contacts Directory ...... 114 Available Literature ...... 106 AES Conventions and Conferences ...... 120 Membership Information...... 108 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 51 NUMBER 3 2003 MARCH CONTENT PAPERS Signal Representation Including Waveform Envelope by Clustered Line-Spectrum Modeling ...... M. Kazama, K.Yoshida, and M.Tohyama 123 When modeling a narrow-band signal, which includes spectral lines close to the peak, the effect of windowing truncation also appears in the region near the peak spectral line. By extending previous research, the authors propose a method to model the spectrum near peaks. This requires an interpolation to find the peak, peak picking, and a model of the effect of windowing in order to extract the slowly varying envelope information. Several examples of audio signals with noise, called clustered line-spectrum modeling, are used to demonstrate practical applications of the approach.

ENGINEERING REPORTS A Moving-Horizon Optimal Quantizer for Audio Signals ...... Graham C. Goodwin, Daniel E. Quevedo, and David McGrath 138 Quantizing, or requantizing a previously digitized signal, produces errors that are perceived as noise. While a time-invariant noise-shaping feedback can move the noise spectrum to a region of less sensitivity, this conventional approach is actually a subset of a more general method. In the proposed extension, quantization decisions use a perceptual model that also analyzes future samples. A look ahead of only three samples, called a moving horizon, is sufficient to produce even lower perceived noise without adding significant computational complexity. Test Signal Generation and Accuracy of Turntable Control in a Dummy-Head Measurement System ...... György Wersényi and András Illényi 150 Unlike the typical application, ultrahigh-accuracy measurements of the head-related transfer function are required when studying the influence of small changes in the acoustic environment near the head. To achieve the needed accuracy, the normal measurement method was modified. Low-crest factor, pseudo- random noise sequences replaced the conventional impulse, and the turntable positioning of the dummy head was modified for high-positional repeatability. Loudspeaker Equalizer Design for Near-Sound-Field Applications ...... Wee Ser, Peng Wang, and Ming Zhang 156 Single-user loudspeaker presentation venues, such as those found in transaural and binaural systems or in personal computers, can not benefit from the conventional form of frequency response equalization. Those optimizations are on-axis signal, average power, or some other generic metric. Single-user applications benefit by optimizing the sound at the listener’s two ears in the near field and no other place. The proposed method demonstrates an equalization method that improves absolute accuracy at both ears and minimizes differential errors between the two ears.

LETTERS TO THE EDITOR Comments on “A Simplified Wavetable Matching Method Using Combinatorial Basis Spectra Selection” ...... Robert Bristow-Johnson 162 Author’s Reply ...... Andrew Horner 163 STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 164 Analog recording; loudspeaker modeling and measurement; audio file transfer; Internet audio delivery; audio metadata

FEATURES 23rd Conference Preview, Copenhagen ...... 170 Calendar...... 172 Program...... 174 Registration Form ...... 179 Moving Digital Audio, Part 2—File Transfer...... 180

DEPARTMENTS News of the Sections ...... 188 Membership Information...... 198 Upcoming Meetings ...... 192 Advertiser Internet Directory...... 200 Sound Track...... 193 Sections Contacts Directory ...... 202 New Products and Developments...... 195 AES Conventions and Conferences ...... 208 Available Literature ...... 197 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 51 NUMBER 4 2003 APRIL CONTENT PAPERS The Bidirectional Microphone: A Forgotten Patriarch ...... Ron Streicher and Wes Dooley 211 After reviewing the history and general issues of microphones and their sensitivity patterns, the authors focus on a pure bidirectional microphone. It is the most difficult to use. Specifically, its major virtue is the ability to place nulls at orientations to suppress unwanted sound pickup. All microphone patterns can be described in terms of a combination of an omnidirectional and figure-of-eight pattern. Many common sense rules are discussed to avoid accidental destruction of microphones’ ribbons. Efficient Tempo and Beat Tracking in Audio Recordings ...... Jean Laroche 226 Automatically measuring musical beat is useful in sound analysis, crossfade synchronization, and audio editing. A proposed off-line system works well for music that has a relatively pronounced beat, yet without creating burdensome demands on computational resources. The algorithm is based on detecting rapid changes in energy within a short-term frequency representation. This produces a more reliable approach because overall energy can mask those spectral components that govern the perception of a beat. A least-square optimization then identifies the best tempo and downbeat location. On the Acoustic Radiation from a Loudspeaker’s Cabinet...... Kevin J. Bastyr and Dean E. Capone 234 Although it is well known that the walls of a loudspeaker cabinet vibrate at low frequencies, the authors determined the actual sound energy being radiated. Initially, a vibrometer was used to measure the surface velocity along the surface, and then a boundary-element method was used to model the acoustic radiation. By applying this method to production loudspeakers, changes in the internal bracing allow the designers to control these unwanted surface resonances, which are true radiating sources. The effects of enclosure vibration affect the overall radiation pattern of the loudspeaker and must be included in the design.

ENGINEERING REPORTS The Virtual Loudspeaker Cabinet ...... J. R. Wright 244 The effective volume of a loudspeaker cabinet can be enlarged by as much as a factor of 3 if activated carbon is included inside the enclosure. The acoustic compliance, the ratio of change in volume with increased pressure, increases because the carbon absorbs and desorbs air. While it is still not commercially viable, the author demonstrates a successful laboratory model, which was judged to sound like a larger cabinet. Special care is needed to ensure that the carbon is uniformly distributed and that it does not absorb water.

LETTERS TO THE EDITOR Comments on “Dipole Loudspeaker Response in Listening Rooms” and “Perception of Reverberation Time in Small Listening Rooms”...... Tomas Salava 248 Author’s Reply ...... James M. Kates 250 Author’s Reply ...... W. J. Davies 251 Comments on “President’s Message”...... David Lloyd ben Yaacov Yehuda Klepper 251 Author’s Reply...... Kees A. S. Immink 251

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 253 Plane-wave tubes; MAD; acoustics and sound-source modeling; microphone measurement and characterization; listening tests

FEATURES 24th Conference Preview, Banff...... 258 Calendar...... 260 Program ...... 262 Registration Form ...... 271 MIDI and Musical Instrument Control ...... 272 Game Audio: Follow-up to Workshop at 113th Convention ...... 277

DEPARTMENTS Review of Acoustical Patents...... 256 Membership Information...... 289 News of the Sections ...... 279 In Memoriam ...... 290 Upcoming Meetings ...... 285 AES Special Publications ...... 293 Sound Track ...... 286 Sections Contacts Directory ...... 298 New Products and Developments ...... 287 AES Conventions and Conferences ...... 304 Advertiser Internet Directory...... 288 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 51 NUMBER 5 2003 MAY

CONTENT

PAPERS Assessment of Voice-Coil Peak Displacement Xmax...... Wolfgang Klippel 307 Peak voice-coil displacement is an important parameter for specifying the maximum acoustic output at low frequencies. However, the absence of a single definition for distortion produces ambiguous results that can not be easily compared. For example, choices include distortion in the voice-coil current or cone displacement. Alternatively, a parametric method that provides more detailed information about the cause of the distortion is proposed. A comparison between performance-based and parameter-based techniques illustrates the advantages and disadvantages. Modal Equalization of LoudspeakerÐRoom Responses at Low Frequencies ...... Aki Mäkivirta, Poju Antsalo, Matti Karjalainen, and Vesa Välimäki 324 Compensation for the dominant low-frequency modes in small rooms traditionally uses equalization filters in cascade with the main sound source. In an alternative implementation, multiple sources produce better modal cancellation when traditional methods fail. Case studies show that the extra degrees of spatial freedom afforded by the additional sources make the system more robust. Modal equalization is a design option when the modal density is not high and when the modes are low frequency. It can also be combined with cascade equalization. A Low-Cost Intensity Probe ...... R. Raangs, W. F. Druyvesteyn, and H.-E. de Bree 344 Unlike ordinary microphones, a sound intensity probe measures the energy flow as a vector direction. It can be computed as the product of scalar pressure and vector velocity. In a conventional probe, velocity is computed as the difference in pressure at a small fixed distance. The authors propose a novel means of directly measuring velocity using the temperature difference between two heated wires mounted in a microminiaturized substrate. When combined with a standard pressure sensor, the probe measures sound intensity over the full spectrum at a single point in space. The paper provides examples of several methods for calibration of the particle velocity sensor used, such as in a standing-wave tube, reverberant room, anechoic space, and reverberation room. Two examples of sound-intensity measurements are provided and are compared with a conventional sound intensity probe.

ENGINEERING REPORTS Industry Evaluation of In-Band On-Channel Digital Audio Broadcast Systems...... David Wilson 358 The proposed techniques for terrestrial broadcasting of digital audio from iBiquity were evaluated using standard metrics: coverage, compatibility, interference, and quality. In order to maintain compatibility with existing AM and FM analog broadcasting, digital information was added as low-amplitude side bands around the main analog spectrum. While the proposed solution achieves the desired goal of preserving the existing competitive balance between radio broadcasters, there is an additional interference outside the protected geographic region. Subjective listening tests confirmed that digital audio improved the quality even at reduced bit rates.

STANDARDS AND INFORMATION DOCUMENTS AES46-2002 AES standard for network and file transfer of audio — Audio-file transfer and exchange — Radio traffic audio delivery extension to the broadcast WAVE file format ...... 369 AES Standards Committee News...... 384 Julian Dunn; resonance of loudspeaker cones

FEATURES 114th Convention Report, Amsterdam ...... 386 Exhibitors...... 402 Program...... 405

TECHNICAL COUNCIL REPORTS Technical Committee Reports: Emerging Trends in Technology ...... 442

DEPARTMENTS News of the Sections ...... 452 Available Literature ...... 461 Upcoming Meetings ...... 458 Membership Information...... 463 Advertiser Internet Directory...... 459 In Memoriam ...... 465 Sound Track...... 460 Sections Contacts Directory ...... 466 New Products and Developments...... 460 AES Conventions and Conferences ...... 472 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 51 NUMBER 6 2003 JUNE

CONTENT

PAPERS Effects of Bandwidth Limitation on Audio Quality in Consumer Multichannel Audiovisual Delivery Systems...... Slawomir⁄ K. Zieli«nski, Francis Rumsey, and S¿ren Bech 475 When transmitting or storing 5.1 program material, if bandwidth must be sacrificed to accommodate channel limitations, the rear surround and the front center channels are the best choices. As long as the front left and right channels maintain the full spectrum, subjective degradation is minimal. Extensive subjective tests support this conclusion even if the bandwidth-limited channels contain foreground audio content. An Efficient Algorithm for the Restoration of Audio Signals Corrupted with Low-Frequency Pulses ...... Paulo A. A. Esquef, Luiz W. P.Biscainho, and Vesa Välimäki 502 Restoring old recordings, especially those that contain clicks at the boundaries where pieces of a broken record have been glued together, requires a model of the corruption. In addition to the transient itself, the cartridge responds to the transient with a long-tailed, low-frequency impulse response, which must also be removed. The authors propose a computationally efficient algorithm, called two-pass split-window filtering, to model and remove this additional component. The results are compared with an autoregressive algorithm.

ENGINEERING REPORTS Study on the Relationship between Some Room Acoustical Descriptors ...... D. Ouis 518 An acoustic model of a performance space provides a means for evaluating those physical measures that predict the subjective experience, such as spaciousness. In order to evaluate the relationship between the various metrics over the space, the author simulated a rectangular space with an additional pair of sidewall balconies. Image reflections and diffraction effects were included to make the model more representative of a real space. This allowed the relationship among parameters to be evaluated. Automated Parameter Optimization for Double Frequency Modulation Synthesis Using a Tree Evolution Algorithm...... B. T. G. Tan and N. Liu 534 As a means of synthesizing complex sounds, several frequency modulation techniques have become popular. However, finding the ideal frequency and amplitude modulation waveforms to create a target signal is difficult, ad hoc, and prone to nonoptimum results. Many optimization algorithms tend to converge to a local solution without adequately exploring the entire space for better solutions. The proposed approach separately explores each local solution rather than focusing on a single part of the space.

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 547 Level meters; digital interfacing; digital synchronization; forensic audio; microphone measurements; audio applications of IEEE 1394

FEATURES History of Spatial Coding ...... Mark F. Davis 554 Automotive Audio...... 570 New Media for Music: An Adaptive Response to Technology ...... 575 Updates and Corrections to the 2002/2003 International Sections Directory...... 578 Education News...... 580 116th Convention, Berlin, Call for Papers...... 596

DEPARTMENTS News of the Sections ...... 582 Advertiser Internet Directory...... 593 Upcoming Meetings ...... 587 In Memoriam ...... 594 Sound Track...... 588 AES Special Publications ...... 597 New Products and Developments...... 589 Sections Contacts Directory ...... 602 Available Literature ...... 591 AES Conventions and Conferences ...... 608 Membership Information...... 592 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 51 NUMBER 7/8 2003 JULY/AUGUST CONTENT PAPERS Full-Sphere Sound Field of Constant-Beamwidth Transducer (CBT) Loudspeaker Line Arrays ...... D. B. (Don) Keele, Jr. 611 Unlike a linear-line array of loudspeakers, which has no means of controlling the horizontal beamwidth, a curved-line circular-arc array exhibits useful properties in three dimensions. Based on a computer simulation, the author shows that the configuration provides horizontal directivity in addition to the expected vertical control. Such arrays have a pear-shaped pattern that is surprisingly uniform over the frequency range. The bending is an extra degree of freedom that allows more control over the radiation pattern. Direct-Radiator Loudspeaker Systems with High Bl ...... John Vanderkooy, Paul M. Boers, and Ronald M. Aarts 625 Increasing the magnetic motor strength of a driver not only improves the efficiency of the loudspeaker and amplifier, but also improves other tradeoffs in the design process. Box volume can be decreased. A study demonstrated the advantages for a small sealed-box configuration, although equalization is required to restore a flat response. Vented systems do not benefit as much from this approach. Psychoacoustic Investigations On Sound-Source Occlusion ...... Hania Farag, Jens Blauert, and Onsy Abdel Alim 635 Virtual space simulation is actually a collection of acoustic attributes, which include objects that cast auditory shadows, an effect known as occlusion. Objects block and change the perception of sound when they are located between the source and the listener. Experiments show that the perceived location of an occluded source is shifted to the edge closest to the listener, which simplifies the computational burden of modeling occluding objects. This result is consistent with the precedence effect. ENGINEERING REPORTS The Differential Pressure Synthesis Method for Efficient Acoustic Pressure Estimation ...... Yufei Tao, Anthony I. Tew, and Stuart J. Porter 647 Calculating the sound field around a complex object, such as the pressure at the two ears of a head, is computationally intensive. Rather than a direct computation, the authors demonstrate an incremental approach to a reference template. The pressure changes produced by each spherical harmonic are precomputed and stored in a database. The target shape is then decomposed into the template references and the sum of spherical harmonics, each of which contributes an incremental change to the pressure. In the case of a dummy head, the results were accurate for wavelengths that were large compared to the spatial perturbations. LETTERS TO THE EDITOR Comments on “Deciphering an Enigma” ...... Marianna Sankiewicz and Gustaw Budzy«nski 657 Author’s Reply to “Comments on ‘Deciphering an Enigma’” ...... Steven Harris 657 STANDARDS AND INFORMATION DOCUMENTS AES47-2002 AES standard for digital audio—Digital input–output interfacing—Transmission of digital audio over asynchronous transfer mode (ATM) networks ...... 659 AES-R4-2002 AES standards project report—Guidelines for AES standard for digital audio— Digital input–output interfacing—Transmission of digital audio over asynchronous transfer mode (ATM) networks, AES47...... 684 AES Standards Committee News...... 704 Mechanical media; audio storage and handling; listening tests; audio connectors; grounding and EMC; audio file transfer and exchange FEATURES 115th Convention Preview, New York...... 714 Calendar...... 716 Exhibitors...... 717 Exhibit Previews...... 722 Demystifying Audio Metadata ...... 744 116th Convention, Berlin, Call for Papers...... 768 25th Conference, London, Call for Papers ...... 769 DEPARTMENTS Review of Acoustical Patents...... 710 Membership Information...... 759 News of the Sections ...... 752 Advertiser Internet Directory...... 762 Sound Track...... 756 In Memoriam ...... 766 Available Literature ...... 757 Sections Contacts Directory ...... 770 Upcoming Meetings ...... 758 AES Conventions and Conferences ...... 776 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 51 NUMBER 9 2003 SEPTEMBER

CONTENT In Memoriam: Patricia Macdonald ...... Roger K. Furness 779

PAPERS Effects of Down-Mix Algorithms on Quality of Surround Sound ...... Slawomir⁄ K. Zieli«nski, Francis Rumsey, and S¿ren Bech 780 When channel limitations prevent the transmission of a full 5.1 surround mix, there are many options for converting to a lesser number of channels using down mixing. Listeners were asked to evaluate eight different algorithms from two listening positions in terms of preferences rather than quality. Unfortunately, different audio cases produced variations in the conclusion about optimum. The presence of a video picture influenced the experience of reduced audio channels. A Study on Head-Shape Simplification Using Spherical Harmonics for HRTF Computation at Low Frequencies ...... Yufei Tao, Anthony I.Tew, and Stuart J. Porter 799 Using a simplified shape for the human head in computing head-related transfer functions (HRTFs) produces errors in the calculated pressures on the surface. A model of a head can be represented as a series of spherical harmonics. This study computes the errors in acoustic pressure that result from truncating the series, which corresponds to low-pass shape filtering. These shape errors follow the corresponding pressure errors for frequencies below 3 kHz. Harmonics to order 11 are sufficient for the low frequencies representation of a head. Beyond order 14 there is no additional improvement. Differences in Performance and Preference of Trained versus Untrained Listeners in Loudspeaker Tests: A Case Study ...... Sean E. Olive 806 The audio industry makes many assumptions about the appropriateness of various quality testing methods, but there have not been any significant studies to validate these assumptions. The choices are reduced to using trained listeners, who are efficient and discriminating, or untrained listeners, who are more representative of the user population. This 18-month study shows that trained listeners produce the same conclusion as 268 untrained listeners when evaluating loudspeakers. Objective Measures of Listener Envelopment in Multichannel Surround Systems ...... Gilbert A. Soulodre, Michel C. Lavoie, and Scott G. Norcross 826 Predicting the degree of listener envelopment is more complex than the traditional measures of lateral energy after the first 80 ms. This detailed study shows that the transition threshold between early and late energy is frequency-dependent. In addition, the loudness of the lateral energy is equally important. A new objective measure is proposed with a very high correlation between perceived envelopment and the calculated metric.

LETTERS TO THE EDITOR “More Comments on President’s Message and Comments” ...... John Woodgate 841

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 842 Sampling frequencies; digital audio synchronization; preservation and restoration of recordings; loudspeaker modeling and measurement

FEATURES 23rd Conference Report, Copenhagen ...... 846 Digital Rights Management...... 855 25th Conference, London, Call for Papers ...... 871

DEPARTMENTS News of the Sections ...... 861 Membership Information...... 872 Sound Track...... 865 Advertiser Internet Directory...... 873 New Products and Developments...... 867 Sections Contacts Directory ...... 874 Upcoming Meetings ...... 868 AES Conventions and Conferences ...... 880 Available Literature ...... 869 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 51 NUMBER 10 2003 OCTOBER

CONTENT

PAPERS Two-Port Representation of the Connection between Horn Driver and Horn ...... Gottfried K. Behler and Michael Makarski 883 Analyzing a loudspeaker system comprised of a horn and a horn driver is more productive if each element is modeled with an approach that is appropriate to the underlying physics. The driver element approximates a classical two port, with electrical voltage and current at the input port and acoustic pressure and velocity at the output port. In contrast, the horn element incorporates a three-dimensional sound radiation pattern with a one-dimensional acoustic input. The model of each element was merged at the connection point to predict the performance of the system’s combination.

ENGINEERING REPORTS Sensitivity of High-Order Loudspeaker Crossover Networks with All-Pass Response ...... Brandon Cochenour, Carlos Chai, and David A. Rich 898 While component tolerances influence the properties of loudspeaker crossover networks and these influences are greatest in high-order filters, the advantages of high-order networks dwarf other issues. Specifically as a listener changes his elevation, the shift in delay among noncoincident drivers dominates the frequency response. High-order filters limit this influence to a narrow-frequency region. Monte Carlo simulations confirmed that the component tolerances, in comparison to delay changes, are a minor aspect of the response.

Wavefront Sculpture Technology...... Marcel Urban, Christian Heil, and Paul Bauman 912 Arrays of discrete loudspeakers are useful for creating a controlled sound field over a wide area, but mathematical and numeric methods often do not provide intuitive insight into the physical process. Using the visual analog of a Fresnel analysis, the authors considered a qualitative approach to the design of loudspeaker arrays to show how interference can be controlled. When this approach was applied to a curved array, the added degree of freedom enabled a wave field to be created that is free of destructive interference over a larger predefined area.

Acoustical Renovation of Tainan Municipal Cultural Center Auditorium ...... Weihwa Chiang, Chingtsung Hwang, and Yenkun Hsu 933 The Tainan auditorium had a reputation for good acoustics, but its reverberation time and spatial acoustics were inadequate for orchestra performances. Because the ceiling had been damaged, the renovation project also offered an opportunity to modify the acoustics. Scale models of the proposed changes were used to compare the conditions before and after the renovation. Simple modifications of the space produced dramatic improvements.

FEATURES 24th Conference Report, Banff...... 946 Advances in Low Bit-Rate Audio Coding ...... 956 Review of Society’s Sustaining Members ...... 965 Updates and Corrections to the 2002/2003 International Sections Directory...... 983

DEPARTMENTS Review of Acoustical Patents...... 943 Available Literature ...... 992 News of the Sections ...... 985 Membership Information...... 993 Sound Track...... 988 AES Special Publications ...... 997 Upcoming Meetings ...... 988 Sections Contacts Directory ...... 1002 New Products and Developments...... 989 AES Conventions and Conferences ...... 1008 Advertiser Internet Directory...... 991 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 51 NUMBER 11 2003 NOVEMBER CONTENT President’s Message ...... Ron Streicher 1011

PAPERS The Effect of Nonlinear Distortion on Perceived Quality of Music and Speech Signals ...... Chin-Tuan Tan, Brian C. J. Moore, and Nick Zacharov 1012 The subjective evaluation of nonlinear distortions often shows a weak correlation with physical measures because the choice of distortion metrics is not obvious. In reexamining this subject, the authors validated a metric based on the change in the spectrum in a series of spectral bins, which when combined leads to a single distortion metric. Distortion was evaluated both objectively and subjectively using speech and music. Robust results support the hypothesis for this approach.

ENGINEERING REPORTS Ultra-High Quality Video Frame Synchronous Audio Coding ...... Michael J. Smithers, Brett G. Crockett, and Louis D. Fielder 1032 When audio signals accompany video information, additional requirements are imposed on audio encoding to allow for frame-based video editing, switching, and splicing. Moreover within the bit budget, the number of channels and their bit allocation is flexible. In the proposed approach audio blocks are designed to match the frame boundaries, but with an additional transitional region that avoids time-domain aliases, a degradation resulting when neighboring blocks are no longer contiguous. Large-Signal Analysis of Triode Vacuum-Tube Amplifiers...... Muhammad Taher Abuelma’atti 1046 With the renewed interest in vacuum tubes, the issue of intrinsic distortion mechanisms becomes relevant again. The author demonstrates a nonlinear model of triodes and pentodes that leads to a closed-form solution when the nonlinearity is represented by a Fourier expansion rather than the conventional Taylor series. When applied to a two-tone sine wave, the analysis shows that the distortion in tube amplifiers is similar to that of the equivalent transistor amplifier. A SPICE analysis confirms the approach. Acoustical Measurements of Traditional Theaters Integrated with Chinese Gardens ...... Weihwa Chiang, Yenkun Hsu, Jinjaw Tsai, Jiqing Wang, and Linping Xue 1054 The acoustics of three Chinese theaters from the nineteenth century were evaluated using the conventional metrics for performance spaces. Similar to the Western tradition, theaters evolved as one of three types: amphitheater, courtyard, and auditorium. However, Chinese theaters were often integrated with privately owned gardens with a diversified design and acoustic architecture. Even with a high degree of spatial irregularity, measurements were consistent with modern theater acoustics.

LETTERS TO THE EDITOR Comments on “History of Spatial Coding”...... Peter Scheiber 1062 Why Is Bass Reproduction from a Dipole Woofer in a Living Room Often Subjectively More Accurate Than from a Monopole Woofer? ...... Siegfried Linkwitz 1062

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 1064 Standards in print

FEATURES Binaural Audio in the Era of Virtual Reality ...... 1066 New Officers 2003/2004...... 1073 2003/2004 AES International Sections Directory...... 1078

DEPARTMENTS News of the Sections ...... 1104 Membership Information...... 1111 Sound Track...... 1108 Advertiser Internet Directory...... 1112 New Products and Developments...... 1108 AES Special Publications ...... 1115 Upcoming Meetings ...... 1109 AES Conventions and Conferences ...... 1120 Available Literature ...... 1110 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 51 NUMBER 12 2003 DECEMBER CONTENT PAPERS Why Are Commercials so Loud? — Perception and Modeling of the Loudness of Amplitude- Compressed Speech...... Brian C. J. Moore, Brian R. Glasberg, and Michael A. Stone 1123 According to urban legend, commercials are broadcast with higher loudness levels than programming. An empirical study confirmed that four-band compressed speech sounds louder than uncompressed speech by as much as 3 dB when the rms levels are matched. An audio engineer can control only the perceived loudness of broadcast program material if a loudness meter is available for monitoring the program. However, loudness models require significant computational power if used in real time. Smart Digital Loudspeaker Arrays ...... M. O. J. Hawksford 1133 With the advent of microminiature transducers, a new class of loudspeaker design fundamentals is required in order to implement programmable radiation beam directions and beamwidths. The primary objective of this study was to develop a processing strategy to obtain a target directional radiation from an array of transducers, each with its own dedicated signal processing. Coherent and diffuse beams can be obtained simultaneously from the same array over a wide frequency range. Localization of 3-D Sound Presented through Headphone—Duration of Sound Presentation and Localization Accuracy...... Fang Chen 1163 Of all the spatial parameters that influence localization accuracy, signal duration is often one of the most important. When the duration is long enough, approaching four seconds, accuracy using headphones is comparable to that of free-field or individual HRTFs. The results of this empirical study are consistent with a wide variety of sound samples. Designers of auditory displays must include signal duration as an important parameter. ENGINEERING REPORTS Reconstruction of Mechanically Recorded Sound by Image Processing ...... Vitaliy Fadeyev and Carl Haber 1172 Two-dimensional image processing offers a modern method to reproduce historic mechanical recordings without using a contact transducer. Moreover, because image processing uses information spread over a wide area, it is easier to remove noise, scratches, and other defects. In addition to avoiding additional degradation by contact transducers, optical decoding of groove undulations produces better audio quality. A contact transducer senses mechanical position at a single point in space and time, an image incorporates mechanical information spanning a large area. This approach may allow automated preservation of endangered audio performances of historic value. LETTERS TO THE EDITOR Comments on “Analysis of Traditional and Reverberation-Reducing Methods of Room Equalization”...... John N. Mourjopoulos 1186 Author’s Reply...... Louis D. Fielder 1189 CORRECTIONS Correction to: “Effects on Down-Mix Algorithms on Quality of Surround Sound” ...... S. K. Zieli«nski, F. Rumsey, and S. Bech 1192 STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 1193 Digital audio synchronization; listening tests; Internet audio quality FEATURES 115th Convention Report, New York...... 1196 Exhibitors ...... 1210 Program...... 1215 11th Tokyo Regional Convention Report...... 1258 Exhibitors ...... 1261 Program...... 1262 Education News...... 1276 Call for Nominations for Board of Governors ...... 1282 Call for Awards Nominations...... 1283 Bylaws: Audio Engineering Society, Inc...... 1289 Index to Volume 51...... 1293 DEPARTMENTS News of the Sections ...... 1271 Advertiser Internet Directory...... 1286 Sound Track...... 1279 In Memoriam ...... 1287 Upcoming Meetings ...... 1279 AES Special Publications ...... 1317 New Products and Developments...... 1280 Sections Contacts Directory ...... 1322 Available Literature ...... 1281 AES Conventions and Conferences ...... 1328 Membership Information...... 1285 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 52 NUMBER 1/2 2004 JANUARY/FEBRUARY

CONTENT

PAPERS Nonlinear Modeling of the Heat Transfer in Loudspeakers ...... Wolfgang Klippel 3 Traditional analysis of a loudspeaker assumes that thermal and electromechanical models can be represented by linear coupling. Careful examination with a variety of music samples shows that such a model fails to produce accurate results because both systems are intrinsically nonlinear. Especially at low frequencies, the cone movement produces cooling and lower temperatures. A linear approach considers only the input power to the thermal model, while a nonlinear approach includes displacement, velocity, and two components of power dissipation. The nonlinear model is more accurate. Simultaneous Measurement of Multichannel Acoustic Systems ...... Alberto González, Pedro Zuccarello, Gema Piñero, and María de Diego 26 Measuring the linear properties of a multichannel audio system can be viewed as a collection of single- channel systems if each channel is measured in isolation. With a large number of input and output channels, a sequential measurements approach takes increasing amounts of time. Using time or frequency multiplexing allows all measurements to be performed simultaneously. A theoretical framework shows the validity of this approach. A New Thermal Model for Loudspeakers ...... Fabio Blasizzo 43 Conventional models of temperature in loudspeakers usually ignore the transport of heat from the forced- air convection cooling produced by movement of the loudspeaker cone. Especially at low frequencies in large woofers, force ventilation is the dominant mechanism for heat transport. Because high temperatures produce distortion and degradation, designers need an accurate means of including thermal tradeoffs. Simulation results show that the new model predicts voice-coil temperature more accurately.

ENGINEERING REPORTS Effect of Arrival Time Correction on the Accuracy of Binaural Impulse Response Interpolation— Interpolation Methods of Binaural Response ...... Mitsuo Matsumoto, Susumu Yamanaka, Mikio Toyama, and Hiroaki Nomura 56 When attempting to create a head-related transfer function (HRTF) for a source that can have a continuous location, spatial HRTFs at discrete locations are generally interpolated to get the desired response. Numerous methods of interpolation have already been investigated, but if the methods include time correction, accuracy is improved. Angular shifts in the source location, in addition to changing the response’s fine structure, also produce a small time shift because the ears are not located at the center of the head. Azimuth changes produce a time shift.

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 62 Secretariat note; peak levels; digital input/output interfacing; storage and handling of media; acoustics and sound source modeling

FEATURES New Horizons in Listening Test Design...... 65 Novel Surround Sound Microphone and Panning Techniques ...... 74 Updates and Corrections to the 2003/2004 International Sections Directory...... 81 117th Convention, San Francisco, Call for Papers...... 99

DEPARTMENTS News of the Sections...... 84 Advertiser Internet Directory...... 95 Sound Track ...... 90 In Memoriam ...... 96 New Products and Developments...... 91 AES Special Publications ...... 101 Upcoming Meetings ...... 92 Sections Contacts Directory ...... 106 Available Literature...... 93 AES Conventions and Conferences ...... 112 Membership Information...... 94 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 52 NUMBER 3

CONTENT

INTRODUCTION High-Resolution Audio...... Rhonda J. Wilson 116

PAPERS Coding for High-Resolution Audio Systems...... J. Robert Stuart 117 To achieve the highest audio quality, one must consider not only each component of the chain but also the entire chain as a system. Furthermore, quality acquires a meaning that depends on the goals, application, and cost tradeoff. Choices for each element—such as sampling rate, encoding format, word size, filtering, and noise floors—may or may not influence the auditory quality of the total system. A review of various channel-coding methods within the context of auditory perception illustrates the principle of a “coding space,” which is the amount of useful information preserved or destroyed. For example, in an archival application the encoding noise floor should be at least two bits lower than the self-noise of the best audio signal.

Audio Analog-to-Digital Converters...... Mike Story 145 By considering the requirements for audio conversion within the wider context of conversion applications, we can better appreciate the implication of choosing a particular approach. Choices include: one bit versus multibit, use of feedback or multistage sequential processing, and switched capacitor versus continuous time. A review of the resulting performance shows the delicate balance among such parameters as accuracy, frequency, and burdens on implementation.

Future Design Challenges for Audio Converter Products ...... Julian Hayes, John Pennock, and Anthony Magrath 159 Extensive discussion about the theoretical limits of various digital conversion techniques, while interesting, ignore the practical implications of implementation difficulties. Physical devices, under economic pressure from the requirement of high yield and low expense, degrade performance to a significant degree. Chip designers must contend with timing errors, substrate noise, internal crosstalk, mismatched components, temperature gradients, nonlinear slew rates, wiring inductance, nonuniform doping, impurities, and numerous other issues. Special processes and computer modeling help reduce these corrupting influences, but problems still remain when attempting to achieve performance to the theoretical limits.

One-Bit Audio: An Overview ...... Derk Reefman and Erwin Janssen 166 While the CD format solidified full digital words of 16 to 24 bit as an audio coding standard, digital conversion technology moved toward oversampling using a few bits or only one bit. By using noise shaping within a sigmaÐdelta modulator, one-bit conversion can produce very high-quality audio. A review of the various implications leads to the conclusion that one-bit coding is an attractive approach rather than converting to the traditional pulse-code modulation.

Lossless Compression of One-Bit Audio ...... Eric Knapen, Derk Reefman, Erwin Janssen, and Fons Bruekers 190 Because the goal of the Super Audio CD is to produce the highest quality, lossless compression offers a way to reduce the storage capacity without sacrificing quality. A proposed design produces compression by using a prediction filter operating on a one-bit audio stream and then uses a probability lookup table to achieve a compression rate greater than 2.5:1 on typical music samples. However, the benefits produce a small uncertainty in playing time. Instantaneous compression rate varies dramatically over the extremes of peak transients or noise and intervals of silence.

Pulse-Code Modulation—An Overview...... Stanley P. Lipshitz and John Vanderkooy 200 The authors provide an overview of pulse-code modulation. They graphically demonstrate the properties of sampling and reconstruction, establishing that PCM allows band-limited signals to be time accurate to infinite precision. Any bandwidth can be accommodated with proper choice of the sampling frequency. The JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 52 NUMBER 4 2004 APRIL CONTENT President’s Message ...... Ron Streicher 331

PAPERS Graphing, Interpretation, and Comparison of Results of Loudspeaker Nonlinear Distortion Measurements...... Alexander Voishvillo, Alexander Terekhov, Eugene Czerwinski, and Sergei Alexandrov 332 For loudspeaker nonlinearity, measurement techniques range from single-tone harmonic distortion, which is easy to interpret but not indicative of performance with music, to reactions to multitone stimuli, which are hard to interpret but highly informative. Because multitone techniques have the potential to predict the perception of nonlinearities, the authors focus on various presentation formats and analysis techniques to make the relevant information in the thousands of intermodulation products accessible and meaningful.

ENGINEERING REPORTS Impedance Compensation Networks for the Lossy Voice-Coil Inductance of Loudspeaker Drivers...... W. Marshall Leach, Jr. 358 The high-frequency rise in the voice-coil impedance of a loudspeaker driver produced by lossy voice-coil inductance can be approximately cancelled by a Zobel network connected in parallel. Such networks improve performance by presenting purely resistive impedance to the crossover network. Although higher order networks can be used, a pair of resistors and capacitors is sufficient for typical drivers. Scalable, Content-Based Audio Identification by Multiple Independent Psychoacoustic Matching ...... Geoff R. Schmidt and Matthew K. Belmonte 366 A software audio search system, as an analog to text searching, allows a target music sample to be identified by matching it to a database containing an inventory of reference samples. Rather than rely on autonomous metadata, the algorithm uses a sequence of vectors based on perceptual attributes. By iteratively testing a progression of such vectors, the algorithm has the ability to trade accuracy versus compute time. With increasing storage capacity to hold virtually unlimited quantities of audio data, an efficient search algorithm is a necessity. On the Detection of Melodic Pitch in a Percussive Background ...... Preeti Rao and Saurabh Shandilya 378 Although many pitch detection algorithms have been proposed over the years, the problem is particularly difficult when melodic instruments are accompanied by percussive background. The authors propose a temporal autocorrelation pitch detector motivated by an auditory model that attempts to suppress errors produced by inharmonic interfering partials of such instruments as a kick drum. Separate processing of frequency channels proved crucial in reducing the distortion products, due to the nonlinear hair-cell model, between the signal harmonics and the interfering partials.

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 392 New AESSC chairman; audio file interchange; audio over IEEE 1394

FEATURES 25th Conference Preview, London ...... 402 Calendar...... 404 Program ...... 405 Registration Form ...... 411 Historical Perspectives and Technology Overview of Loudspeakers for Sound Reinforcement ...... J. Eargle and M. Gander 412 DSP in Loudspeakers...... 434 Surround Live Summary...... Frederick Ampel 440 26th Conference, Baarn, Call for Papers ...... 457

DEPARTMENTS Review of Acoustical Patents...... 395 Membership Information...... 451 News of the Sections...... 443 Advertiser Internet Directory...... 453 Upcoming Meetings ...... 447 In Memoriam ...... 456 Sound Track ...... 448 Sections Contacts Directory ...... 458 New Products and Developments...... 449 AES Conventions and Conferences ...... 464 Available Literature...... 450 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 52 NUMBER 5 2004 MAY

CONTENT

PAPERS Analysis of Loudspeaker Line Arrays ...... Mark S. Ureda 467 A set of mathematical expressions is provided to estimate the performance of loudspeaker line arrays. These include expressions for the polar response, on-axis and off-axis pressure responses, and two-dimensional pressure fields of straight-line, curved, J, and progressive line arrays. In addition, expressions are provided to analyze the effects of curved radiating sources and gaps between sources in line arrays. Several examples are provided to compare estimated performance against measured data. Fast Convolution Technique Using a Nonuniform Sampling Scheme: Algorithm and Applications in Audio Signal Processing...... Mingsian R. Bai and Pingshun Zeung 496 Using a nonuniform sampling, a fast convolution algorithm greatly reduces the complexity and increases the computational efficiency by providing high resolution at low frequencies and low resolution at high frequencies. Examples of a head-related transfer function and a reverberant room response illustrate good subjective performance even though the results are distinguishable from direct convolution. This approach exploits the differences in spectral resolution for human hearing.

ENGINEERING REPORTS Measurement of Reverberation Times Using a Wavelet Filter Bank and Application to a Passenger Car ...... Sang-Kwon Lee 506 Measuring the reverberation time in small spaces using traditional methods is difficult because the product of the bandwidth and reverberation time is too small. A wavelet transform method using a wavelet filter bank has been successfully used to measure the reverberation time of the passenger compartment of an automobile, where such times were on the order of 0.05 seconds. Synthetic impulse responses from a toy balloon were used as an impulse response for exciting the space. Wavetable Matching of Pitched Inharmonic Instrument Tones...... Clifford So and Andrew B. Horner 516 By relaxing the normal assumption of harmonic tones in wavetable synthesis, a new approach allows for using wavetables for plucked instruments, such as the Chinese qin and yangqin. The new method uses a hierarchical grouping of the original tone’s partials based on their normalized frequency deviation. Using a fully automatic operation, the results show slight improvement on the perceived match with harmonic tones and a greatly improved match on pitched inharmonic tones.

LETTERS TO THE EDITOR Dipole, Monopole, or Near-Field Woofer—Physics and Perception...... Tomas Salava 530 Author’s Reply...... Siefried Linkwitz 532 Comments on “Why Is Bass Reproduction from a Dipole Woofer in a Living Room Often Subjectively More Accurate Than from a Monopole Woofer?” ...... Frank Fahy 532

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 533 Standards in Action: AES47 professional audio networking

FEATURES Wavefield Synthesis: Evolution from Stereophony and Some Practical Challenges ...... 538 117th Convention, San Francisco, Call for Workshop Participants...... 569

DEPARTMENTS Review of Acoustical Patents...... 535 Membership Information...... 556 News of the Sections...... 544 Advertiser Internet Directory...... 557 Sound Track ...... 550 In Memoriam ...... 567 New Products and Developments...... 552 Sections Contacts Directory ...... 570 Upcoming Meetings ...... 554 AES Conventions and Conferences ...... 576 Available Literature...... 554 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 52 NUMBER 6 2004 JUNE CONTENT PAPERS Efficient Generation of Multichannel Dither Signals...... Robert A. Wannamaker 579 When a dither source is needed for multichannel quantization, efficient techniques reduce the computational burden of computing each channel independently. By using appropriate matrix transformations, a single rectangular probability density function (RPDF) random number per sample per channel can be used to produce independent identically distributed (iid) triangular probability density function (TPDF) dither for each channel. After quantization, the errors in each channel are uncorrelated with one another and each has an input-independent mean and variance. Time-Quantized Frequency Modulation, Time-Domain Dither, Dispersive Codes and Parametrically Controlled Noise Shaping in SDM...... M. O. J. Hawksford 587 Comparing sigma–delta modulator (SDM) performance to a mathematically equivalent coding technique based on linear frequency modulation (LFM) and time-domain quantization provides additional insight into the noise behavior of SDM. Normally if the conclusions drawn from studies of linear quantization and triangular dither are applied to SDM, then the two-level quantizer range is violated and instability results. Nevertheless, the chaotic-like loop behavior of high-order SDM even with apparent suboptimal dither demonstrates low correlation distortion and is shown here to be insensitive to dither statistics. The LFM model applies dither in the time domain rather than the amplitude domain and does not violate these assumptions. Augmented Reality Audio for Mobile and Wearable Appliances ...Aki Härmä, Julia Jakka, Miikka Tikander, Matti Karjalainen, Tapio Lokki, Jarmo Hiipakka, and Gaëtan Lorho 618 In a portable device, integrating environmental sounds with synthetically generated audio leads to the concept of a wearable device that produces augmented reality. Listeners wear a headset configuration that includes a binaural microphone and stereophonic headphones. In addition to feeding sounds of the environment to the headphones, an auxiliary input provides the means for reproducing recorded audio in a virtual space. Listening tests with a prototype system showed that some experienced listeners found it difficult to distinguish between real and virtual sources. Room Sizing and Optimization at Low Frequencies ...... Trevor J. Cox, Peter D’Antonio, and Mark R. Avis 640 In critical listening environments, the modes in a room of low volume produce an uneven frequency response and extended decay rates at low frequencies. Using a cost metric based on minimizing the deviations from the flattest possible modal response, the authors propose a new method for choosing the appropriate dimensions for a room of a given volume. While there is a numerically optimum solution, many local minima are equivalent in terms of quality, which then allows for incorporating the physical constraints of real buildings. LETTERS TO THE EDITOR Comments on “Wavefront Sculpture Technology”...... Chao Jiang and Yong Shen 652 Authors’ Reply...... M. Urban, C. Heil, and P. Bauman 653 CORRECTIONS Correction to “Graphing, Interpretation, and Comparison of Results of Loudspeaker Nonlinear Distortion Measurements”...... A. Voishvillo, A. Terekhov, E. Czerwinski, and S. Alexandrov 655 Correction to “Historical Perspectives and Technology Overview of Loudspeakers for Sound Reinforcement”...... J. Eargle and M. Gander 655 STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 656 Audio measurements; metadata FEATURES How Loud Is My Broadcast?...... 662 DEPARTMENTS Review of Acoustical Patents...... 659 Membership Information...... 679 News of the Sections...... 670 Advertiser Internet Directory...... 689 Upcoming Meetings ...... 673 In Memoriam ...... 689 Sound Track ...... 675 Sections Contacts Directory ...... 690 New Products and Developments...... 676 AES Conventions and Conferences ...... 696 Available Literature...... 678 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 52 NUMBER 7/8 2004 JULY/AUGUST

CONTENT PAPERS Predicting the Perceived Quality of Nonlinearly Distorted Music and Speech Signals ...... Chin-Tuan Tan, Brian C. J. Moore, Nick Zacharov, and Ville-Veikko Mattila 699 An analytical model predicts the perceived quality of speech and music when subjected to various forms of nonlinear distortion, thus providing the ability to evaluate audio transducers and transmission systems. The model incorporates the filtering produced by the auditory system so that the perceptual consequences of spurious spectral components are correctly evaluated. By cross-correlating each spectral bin of the input and output signals, the measure of distortion, called Rnonlin, accurately predicts the subjective ratings of listeners. This approach improves on the earlier metric, called Distortion Score, which was less accurate for real transducers. Multi-Actuator Panels (MAPs) as Loudspeaker Arrays for Wave Field Synthesis .....Marinus M. Boone 712 Distributed mode loudspeakers become suitable for wave field synthesis when multiple exciters are embedded in a single panel. In contrast, a large number of loudspeaker panels is not efficient and has low-frequency limitations. As long as the initial part of the impulse response of individual drivers is phase consistent, deviations from an ideal response can be corrected with filtering. Increasing the internal damping by applying a foam board panel was sufficient to achieve accurate wave front curvature as would be obtained from real sources. Multi-actuator panel arrays of loudspeakers are lightweight and thin and can be readily mounted on wall surfaces. Hierarchical Automatic Audio Signal Classification ...... Juan José Burred and Alexander Lerch 724 The advantages and disadvantages of using a hierarchical system for analyzing and classifying audio file content are explored. Such systems are analogous to content analysis for text material. In the hierarchical approach, top-level tree decisions, such as distinguishing between speech and music, approach 95% accuracy, while the more subtle distinctions lower in the tree, such as genres of chamber music, remain at a modest 50%. The authors provide an extensive review of the state of the art in order to place their research into perspective.

ENGINEERING REPORTS A Frequency-Domain Approach to Multichannel Upmix ...... Carlos Avendano and Jean-Marc Jot 740 Because of the wide availability of mulitchannel reproduction equipment and the limited availability of music recorded for formats other than stereo, upmixing a two-channel recording into multichannel format (for example 5.1) would be very useful. By comparing the two stereo channels, it is possible to identify and unmix amplitude-panned sources and to identify and extract background spatial ambience. This allows the redistribution of spatial information and the creation of additional channels to be rendered by the multichannel equipment. The algorithm is based on analyzing the two channels in the time–frequency domain and then observing the degree of similarity and correlation between them.

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 750 Digital audio connectors; synchronization; transfer technologies; listening tests; shielding; file interchange; Internet audio

FEATURES 116th Convention Report, Berlin...... 756 Exhibitors ...... 772 Program...... 776 117th Convention Preview, San Francisco...... 828 Exhibitors ...... 831 Exhibit Previews ...... 835 Education News...... 860

DEPARTMENTS News of the Sections...... 862 Membership Information...... 868 Sound Track ...... 866 Advertiser Internet Directory...... 871 Available Literature...... 867 Sections Contacts Directory ...... 873 Upcoming Meetings ...... 868 AES Conventions and Conferences ...... 880 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 52 NUMBER 9 2004 SEPTEMBER

CONTENT

PAPERS Errors in Real-Time Room Acoustics Dereverberation ...... Panagiotis D. Hatziantoniou and John N. Mourjopoulos 883 While researchers have been studying methods for removing the effects of room acoustics for over 20 years, results are often inconsistent between computer simulations and real applications. This discrepancy has not been formally studied. Errors in measurements of real spaces are significantly higher than expected, even when they are carefully performed. Additionally, when combined with long filters, perceptual artifacts are often worse than the advantages of such systems. High-Q poles used in such filters are very sensitive to listener location and to time-varying acoustic noise present inside the room. By using complex smoothing, which implies a reduction in the degree of room compensation, unpleasant artifacts are greatly reduced. Development and Validation of a Method for Predicting the Perceived Naturalness of Sounds Subjected to Spectral Distortion ...... Brian C. J. Moore and Chin-Tuan Tan 900 Having partitioned distortion into linear and nonlinear distortion and having explored the degree to which such distortions degrade the perception of naturalness, the authors now propose a model to explain the perceptual effects of linear distortion, namely, irregularities in the frequency response. Using the data from 168 filtering conditions, a perceptual model based on excitation patterns has been developed to predict subjective judgments. The model is based on the difference between the excitation patterns for undistorted and distorted pink noise. Two validation experiments supported the model. Interpositional Transfer Function for 3D-Sound Generation ...... F. P. Freeland, L. W. P. Biscainho, and P. S. R. Diniz 915 In order for head-related transfer functions to gain widespread use in binaural audio applications, there needs to be efficient ways for interpolating among a limited number of reference cases that are quantized in elevation and azimuth without loss of perceived accuracy. A triangular interpolation combined with an auxiliary function, called interpositional transfer function, save more than 40% of the operations required by the traditional bilinear methods. This method was employed in a system that generated moving locations. Measurement and Application of Equivalent Input Distortion ...... Wolfgang Klippel 931 Because a loudspeaker can be considered as a single-input, multiple-output transducer, distortion should ideally be measured at multiple spatial locations. This produces a massive collection of data, much of which is redundant. Rather, the author shows that the dominant nonlinearities add distortion to the input signal, which is transferred by a linear system to each point in space. This model leads to a new measurement technique that gives deeper insight into the distortion mechanisms and the influence of the acoustical environment, noise, and parasitic vibrations.

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 948 Digital audio measurement; storage and handling; digital library and archive systems; acoustics—sound source modeling; loudspeaker measurement; IEEE 1394; audio metadata

FEATURES 25th Conference Report, London...... 952 Bass Handling in Spatial Reproduction ...... 962 118th Convention, Barcelona, Call for Papers ...... 991

DEPARTMENTS News of the Sections...... 968 Membership Information...... 981 Sound Track ...... 977 Advertiser Internet Directory...... 982 Upcoming Meetings ...... 978 Sections Contacts Directory ...... 993 New Products and Developments...... 979 AES Conventions and Conferences ...... 1000 Available Literature...... 980 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 52 NUMBER 10 2004 OCTOBER

CONTENT

PAPERS Subjective Investigations of Inverse Filtering ...... Scott G. Norcross, Gilbert A. Soulodre, and Michel C. Lavoie 1003 Much of the research on inverse filtering to correct room or loudspeaker irregularities assumes (without confirmation) that such techniques will improve the subjective listening experience. When this assumption is carefully tested, surprisingly, many techniques actually degrade overall audio quality rather than improve it. Two kinds of inverse filtering were tested: time-domain least squares and frequency deconvolution. Some additional techniques avoided perceptual artifacts but with an inconsistent amount of improvement. Analysis of a Folded Acoustic Horn...... Andrew Bright, Keith Holland, and Frank J. Fahy 1029 Advanced analysis techniques, such as the boundary-element method (BEM), show that a folded horn can be represented by a one-parameter model at low frequencies. Such a model is able to reproduce the throat and transfer impedances as well as the pressure response with high accuracy below 300 Hz. At higher frequencies a more complex model is required. Although the BEM method can contribute to understanding low-frequency folded horns, it remains a complex analysis technique requiring specialized skills. The Distributed Edge Dipole (DED) Model for Cabinet Diffraction Effects ...... M. Urban, C. Heil, C. Pignon, C. Combet, and P. Bauman 1043 A simple model, called distributed edge dipole, is proposed to explain the effects of cabinet edge diffraction on the radiated sound from a direct-radiating loudspeaker when mounted in an enclosure. In comparison to two other techniques, the proposed model more accurately predicts measurements of a thin circular baffle over 50 to 1000 Hz and over a wide angular range from 0 to180 degrees. More specifically, the improvements were obtained in the boundary region between the forward and backward directions.

COMMUNICATIONS Subjective Loudspeaker Testing for Accuracy ...... David Lloyd ben Yaacov Yehuda Klepper 1060 Discussions about subjective loudspeaker preferences often ignore the need for a rating scale to evaluate accuracy. Preferences and accuracy are different perceptual qualities. Accuracy relates to the degree to which a reproduced sound field is subjectively equivalent to a corresponding live presentation of the same source. There is no proof that preferences among different individuals will match accuracy.

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 1065 Microphone measurement

FEATURES A Symposium on Multichannel Audio for Radio Broadcasters...... 1066 Review of Society’s Sustaining Members ...... 1072 118th Convention, Barcelona, Call for Papers ...... 1111 26th Conference, Denver, Call for Papers ...... 1112

DEPARTMENTS Reviews of Acoustical Patents...... 1062 Available Literature...... 1102 News of the Sections...... 1094 Membership Information...... 1103 Upcoming Meetings ...... 1097 In Memoriam ...... 1110 Advertiser Internet Directory...... 1097 Sections Contacts Directory ...... 1113 Sound Track ...... 1098 AES Conventions and Conferences ...... 1120 New Products and Developments...... 1100 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 52 NUMBER 11 2004 NOVEMBER CONTENT President’s Message...... Theresa Leonard 1123 PAPERS Dithered Noise Shapers and Recursive Digital Filters ...... Stanley P. Lipshitz, Robert A. Wannamaker, and John Vanderkooy 1124 Quantizers combining the use of colored, nonsubtractive dither with or without noise-shaping error feedback are closely examined for the first time. In particular, it is shown that the appropriate use of spectrally shaped dither signals entails subtle practical and theoretical considerations, especially if such dithers are combined with noise-shaping schemes. A rigorous analysis of systems employing such dither signals with and without feedback is undertaken, yielding practical guidelines that ensure satisfactory results in applications. In particular, it is shown that the class of dither signals suitable for combination with noise shaping is greatly restricted. Motion-Tracked Binaural Sound...... V. Ralph Algazi, Richard O. Duda, and Dennis M. Thompson 1142 By using a head tracking system that selects from an array of microphones placed on a surface that approximates the listener’s head, the authors have created an alternative to the conventional binaural recording technique. Based on the orientation of the listener, the appropriate microphone is selected or the signals from a pair of microphone signals are interpolated. Head tracking provides strong dynamic cues that create a strong sense of realism with a reduced need for pinna matching. This approach supports multiple listeners from a single microphone array. Importance and Representation of Phase in the Sinusoidal Model ...... Tue Haste Andersen and Kristoffer Jensen 1157 While the importance of differential phase among the components of an audio signal has been debated over the years, experiments show that both synthesized and encoded audio need to consider phase integrity. Subjective listening tests with sounds that were synthesized with varying amounts of phase information clearly demonstrate the need to use a reliable phase model, especially with common harmonic musical sounds. A novel phase representation, called partial-period phase, characterizes phase evolution as an almost stationary parameter. ENGINEERING REPORTS Direct Approximate Third-Order Response Synthesis of Vented-Box Loudspeaker Systems ...... Bernat Llamazares 1170 Extending the earlier work on vented-box loudspeaker systems, a new approach is proposed that provides approximate third-order frequency-response alignments characterized by featuring a good transient response at reduced efficiency for the lower frequencies. These new alignments are very suitable for low-resonance, low-Q drivers, producing a response characteristic midway between a second-order sealed-box and a fourth-order vented-box loudspeaker system. This approach provides an additional degree of freedom in the design. CORRECTIONS Correction to “Analysis of Loudspeaker Line Arrays” ...... Mark S. Ureda 1176 STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 1177 Synchronization; optical disks; media storage; file interchange; jitter FEATURES Metadata Revisited: Six New Things to Know About Audio Metadata ...... 1178 Digital Archive Strategies and Solutions for Radio Broadcasting...... 1180 New Officers 2004/2005...... 1185 26th Conference, Denver, Call for Papers ...... 1200 DEPARTMENTS News of the Sections...... 1188 Membership Information...... 1195 Upcoming Meetings ...... 1192 Advertiser Internet Directory...... 1197 Sound Track ...... 1192 Sections Contacts Directory ...... 1201 New Products and Developments...... 1193 AES Conventions and Conferences ...... 1208 Available Literature...... 1194 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 52 NUMBER 12 2004 DECEMBER CONTENT PAPERS Subtractive and Nonsubstractive Dithering: A Mathematical Comparison ...Robert A. Wannamaker 1211 The relative advantages and disadvantages of subtractive and nonsubtractive dithering are explored from a mathematical perspective. Subtractively dithered systems can yield quantization errors that are statistically independent of the input signal, but that require the dither signal be either transmitted or reconstructed at the receiver. In contrast, nonsubtractively dithered systems avoid this drawback but increase the level of noise at the output and can only render a specified number of statistical error moments independent of the system input. Nonetheless, appropriately chosen nonsubtractive dither signals prove suitable for audio and many other applications. The treatment presented extends to include new results regarding the use of spectrally colored dither signals in systems with and without noise-shaping error feedback. Measuring and Predicting the Perceived Quality of Music and Speech Subjected to Combined Linear and Nonlinear Distortion ...... Brian C. J. Moore, Chin-Tuan Tan, Nick Zacharov, and Ville-Veikko Mattila 1228 A new model is presented for predicting the perceived quality of audio signals subjected to both linear and nonlinear distortion. Earlier research produced metrics for predicting the effects of linear distortion (frequency response irregularity) and nonlinear distortion (production of spurious spectral components). The new model, which includes both metrics, provides predictions that correlate highly with results of subjective tests: correlations were 0.90 for music and 0.85 for speech. Circular Recital Hall Design Considering Source Directivity ...... Wei-Hwa Chiang, Yi-Nuo Chao, Jow-Yeh Lee, and Hui-Ping Wu 1245 During the remodeling of the Carrie Chang Music Hall, early reflections were incorporated into the acoustical design in order to compensate for the loss of high frequencies in those seats that were off axis. The design concentrated on several issues: changes in tone quality resulting from source directivity, sound focusing from curved surfaces, and coloration due to discrete early reflections. Computer and scale models allowed for acoustic analysis during successive design phases. ENGINEERING REPORTS Study of the Directional Characteristics of a Piston Mounted on a Surface of Zero Acoustic Impedance ...... José Luis Barros, Jorge Cárdenas, and Jorge Sommerhoff 1254 The surface impedance of a loudspeaker baffle strongly influences the directionality of the radiation pattern. By contrasting the radiation pattern of a vibrating piston mounted in a surface having infinite impedance with one having zero impedance, the importance of surface impedance is clearly demonstrated. Because energy cannot flow horizontally in a zero impedance surface, energy is concentrated in the axial direction. A two-dimensional model produced results that were consistent with those measured in the laboratory. LETTERS TO THE EDITOR Comments on “Coding for High-Resolution Audio Systems” ...... David Moran, Roy Allison, and E. Brad Meyer 1259 ...... David Hadaway 1259 Author’s Reply ...... J. Robert Stuart 1259 STANDARDS AND INFORMATION DOCUMENTS Special Feature: Real-World Applications of ATM Networking for Professional Audio Using the AES47 Standard...... David Errock 1265 FEATURES The World of Digital Radio...... 1272 Call for Nominations for Board of Governors ...... 1290 Call for Awards Nominations...... 1291 12th Regional Convention, Tokyo, Call for Papers ...... 1299 27th Conference, Copenhagen, Call for Papers...... 1300 Bylaws: Audio Engineering Society, Inc...... 1301 Index to Volume 52 ...... 1305 DEPARTMENTS Reviews of Acoustical Patents...... 1262 Membership Information...... 1292 News of the Sections...... 1280 Advertiser Internet Directory...... 1296 Sound Track ...... 1286 In Memoriam ...... 1297 New Products and Developments...... 1287 Sections Contacts Directory ...... 1321 Available Literature...... 1289 AES Conventions and Conferences ...... 1328 Upcoming Meetings ...... 1289 p2_TOCJan 1/3/05 10:16 AM Page 1

JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 53 NUMBER 1/2 2005 JANUARY/FEBRUARY CONTENT New Editor of the Journal ...... Theresa Leonard 3 PAPERS Development and Initial Validation of a Multichannel Audio Quality Expert System ...... S⁄lawomir Zielinski,´ Francis Rumsey, Rafael Kassier, and Søren Bech 4 When a fixed channel bandwidth must be allocated among different types of services, such as sound, picture, and data, the audio engineer must arbitrate among conflicting demands on bandwidth. Is it better to have a lesser number of high-quality channels or more channels of lower quality? This research creates a predictive measure of graceful degradation with limited audio channel capacity. Subjective tests confirm that the proposed objective metrics predict audio quality as a function of channel bandwidth, as a function of down-mix algorithm, and as a combination of both. A New Cognitive Model of Objective Assessment of Audio Quality ...... Jayme Garcia Arnal Barbedo and Amauri Lopes 22 The objective measures provided by the current ITU Perceptual Evaluation of Audio Quality psychoacoustic standard fail to match the subjective experience under many conditions. An alternative model based on a cognitive model improves the correlation between subjective and objective measures. The new model extracts a set of parameters from the audio signal, which are then mapped into a single metric to predict subjective quality. Six cognitive parameters are extracted from a filter-bank model. ENGINEERING REPORTS Multiple Piano Note Identification Using a Spectral Matching Method with Derived Patterns ...... L. I. Ortiz-Berenguer, F. J. Casajús-Quirós, and S. Torres-Guijarro 32 Detecting the component notes in a chord depends upon the particular musical instrument. By restricting the research to piano chords, and by using a spectral pattern-matching technique, the proposed approach successfully identifies up to four components of the chord. Chords are analyzed note by note, iteratively removing the contribution of each once identified. Spectral patterns of notes, derived from an acoustic model of a piano, were determined during a training session. Auditory Evacuation Beacons ...... Sander J. van Wijngaarden, Adelbert W. Bronkhorst, and Louis C. Boer 44 Conventional auditory beacons, emergency sounds that guide people to a safe exit when vision is obscured by smoke, use modulated noise. But such signals also require explicit verbal instructions in order to navigate to an exit. A new signal was designed as a combination of a chime sound with a spoken message. In a tunnel environment without prior instructions to the participants, the evacuation success rate was 16% for conventional beacons and 87% for the newly designed beacons. Furthermore, by exploiting the precedence effect through the application of time delays, 88% of the participants were able to follow the sound to its location in a simulated ship’s interior. STANDARDS AND INFORMATION DOCUMENTS Standards in print; digital audio connectors; calls for comment on shielding and MADI; reorganization of SC-06; digital audio measurement; input/output interfacing; audio file transfer...... 54

FEATURES 117th Convention Report, San Francisco ...... 58 Exhibitors ...... 74 Program...... 79 The Software Studio in the Age of Audio Networking ...... 124 Some Thoughts on the Dynamics of Reproduced Sound...... Neville Thiele 130 Education News...... 133 12th Regional Convention, Tokyo, Call for Papers ...... 150 27th Conference, Copenhagen, Call for Papers...... 151 119th Convention, New York, Call for Papers ...... 152 DEPARTMENTS News of the Sections...... 135 Membership Information...... 143 Upcoming Meetings ...... 139 Advertiser Internet Directory...... 147 Sound Track ...... 140 In Memoriam ...... 149 New Products and Developments...... 141 Sections Contacts Directory ...... 153 Available Literature...... 142 AES Conventions and Conferences ...... 160 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 53 NUMBER 3 2005 MARCH

CONTENT

PAPERS Vertical Localization of Sound from Multiway Loudspeakers ...... Sam Ferguson and Densil Cabrera 163 While most loudspeaker designers are concerned with localization in the horizontal plane, perceived vertical location usually does not receive sufficient attention. When synchronous and asynchronous noise bands at high and low frequencies are presented, the vertical locations of each signal are not necessarily aligned. Moreover, the location of the high-frequency band tends to dominate the location of the low-frequency band when both are simultaneously present.

Comparison of Basic Audio Quality and Timbral and Spatial Fidelity Changes Caused by Limitation of Bandwidth and by Down-Mix Algorithms in 5.1 Surround Audio Systems ...... S⁄lawomir K. Zielinski,´ Francis Rumsey, Rafael Kassier, and Søren Bech 174 When there is inadequate channel bandwidth to transmit full high-quality audio in multiple surround channels, spatial fidelity should be sacrificed. Mixing down multiple channels to a smaller number is preferred over limiting the bandwidth of all channels. Timbral quality is a more important contributor to basic audio quality than spatial quality in the context of modern home cinema systems. Intercomparison Measurements of Room Acoustical Parameters and Measures for Speech Intelligibility in a Room with a Sound System ...... Kurt Eggenschwiler and Rainer Machner 193 The qualitative control of specifications for sound systems and rooms is becoming more and more important. But what is the uncertainty of the related acoustics measurements? Intercomparison measurements showed that the standard deviations were often within the region of the perception thresholds. Achieving consistent results may depend on such factors as better training of acousticians.

COMMUNICATIONS Wavetable Synthesis Strategies for Mobile Devices ...... Robert C. Maher 205 Unlike the design choices made for wavetable synthesis of music, strategies for customized ring tones in cell phones and pagers require a different optimization. In this application: higher levels of compression are needed; memory storage is limited; and compute power is sparse. However, by careful selection of the sample set and its representation during encoding, a new strategy achieves 12-bit performance with up to 50% compression.

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 214 Audio over IEEE 1394; Internet audio quality; analog recording; transfer technologies; storage and handling of media; digital library and archive systems; forensic audio; sound source modeling; loudspeaker measurement; grounding and EMC practices

FEATURES 118th Convention Preview, Barcelona...... 218 List of Exhibitors and Previews ...... 220 New Developments in Low Bit-Rate Coding ...... 235 119th Convention, New York, Call for Papers ...... 263

DEPARTMENTS News of the Sections...... 242 Advertiser Internet Directory...... 251 Upcoming Meetings ...... 245 In Memoriam ...... 261 Sound Track ...... 246 AES Annual Report ...... 264 Available Literature...... 249 Sections Contacts Directory ...... 265 Membership Information...... 250 AES Conventions and Conferences ...... 272 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 53 NUMBER 4 2005 APRIL

CONTENT

PAPERS System Measurement and Identification Using Pseudorandom Filtered Noise and Music Sequences...... M. O. J. Hawksford 275 Either music sequences or pseudorandom filtered noise can be used to evaluate simultaneously the transfer function and distortion mechanisms in audio systems. This approach is applicable to amplifiers, signal processors, digital-to-analog converters, loudspeakers, and perceptual coders. In addition, the technique allows nonlinear modeling using a simplified Volterra model. Because the technique is a single-pass analysis, the effect of time-varying changes is minimized.

Synthesis of Room Responses Using Virtual Source Representation with Application in Reverberator Design...... Mingsian R. Bai and Kwuen-Yieng Ou 297 Conventional methods for synthesizing reverberation and a spatial impression consider the space separately from the sound source. In the proposed method the sound field is represented by a mesh of virtual sources at the boundary surface, rather than by a simple image method or ray-tracing procedure. Physical settings of the space are naturally incorporated into the model. Numerical simulations were performed for a rectangular room and a concert hall, and subjective listening tests confirmed that the technique is capable of rendering remarkable realism. Only the early part of the reverberation process is represented in this approach.

Direct-Radiator Loudspeaker Efficiency at Fundamental Resonance ...... Carlo Zuccatti 307 For direct-radiator loudspeakers, the efficiency at resonance is often higher than the rated efficiency at midfrequencies, which are assumed to be the more useful frequency range. Band-limited systems, such as subwoofer enclosures using loudspeakers operating near their resonant frequency, can take advantage of this effect, especially with low DC resistance voice coils.

ENGINEERING REPORTS A Comparison between Local Search and Genetic Algorithm Methods for Wavetable Matching ...... Simon Wun and Andrew Horner 314 The effectiveness and efficiency of wavetable synthesis of musical notes require a strategy for selecting the basis spectra from which the notes can be synthesized. This work describes a local search method for basis spectra that improves the performance with simple selection criteria. Five methods converged to within an error range of about 1%, though occasionally the algorithm gets stuck on defective local optimum.

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 326 MADI guidelines; recorded fluxivity; magnetic tape handling; microphone measurements and digital interface

FEATURES Multichannel Audio Systems and Techniques...... 329 Shake, Rattle, and Roll; Getting Immersed in Multisensory, Interactive Music via Broadband Networks ...... Wieslaw Woszczyk, Jeremy Cooperstock, John Roston, and William Martens 336

DEPARTMENTS Upcoming Meetings ...... 344 Membership Information...... 355 News of the Sections...... 345 In Memoriam ...... 360 Sound Track ...... 348 Sections Contacts Directory ...... 361 New Products and Developments...... 350 AES Conventions and Conferences ...... 368 Available Literature...... 352 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 53 NUMBER 5 2005 MAY

CONTENTS

PAPERS Effect of Noise and Transducer Variability on the Performance of Circular Microphone Arrays ...... M. A. Poletti 371 As a low-cost alternative for three-dimensional microphone arrays, circular arrays are appropriate for analyzing room acoustics, recording live sound fields, and providing teleconferencing applications. The ideal performance of such arrays is limited by additive noise and transducer variability. These two effects are quantitatively examined for the simple case of incident plane waves. The effective signal-to-noise ratio depends on the frequency, the area of the array, and the density of microphones. Variations in phase among microphones produce high-order polar response errors at low frequencies.

The Active Listening Room: A Novel Approach to Early Reflection Manipulation in Critical Listening Rooms ...... Amber Naqvi and Francis Rumsey 385 Rather than trying to change the natural acoustics of a space, adding active panels and loudspeakers creates an active listening area within an existing space. Simulations using a computer-based acoustic design package determine the required parameters for creating the target space. This approach is more flexible than standardized reference listening rooms. In effect, the acoustics of a small region within a large space is being controlled.

Audible Noise Suppression with a Real-Time Broad-Band and Superdirective Microphone Array ...... Jose-Luis Sanchez-Bote, Joaquin Gonzalez-Rodriguez, and Javier Ortega-Garcia 403 By extending algorithms used for noise suppression from a single microphone to a 15-microphone nested linear array, extra spatial information then contributes additional noise reduction. This extra information is better able to improve the clean speech signal estimates, and hence to make better decisions about in which spectral regions the noise is masked. The system has been evaluated off-line and in highly reverberant spaces under different noise conditions. The performance of superdirective beams can thus be improved.

ENGINEERING REPORTS Low-DC-Resistance, Low-Frequency Loudspeaker Enclosures ...... Carlo Zuccatti 419 By using loudspeaker drives with low voice-coil resistance, the sensitivity near resonance can be significantly increased. However at frequencies far from resonances, an additional passive filter provides safe impedance to the amplifier. The combination improves the sensitivity and power output in low-frequency enclosures. This approach has an extra degree of freedom not normally found with such enclosures.

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 429 Shielding; high-resolution multichannel audio interconnection (HRMAI); metadata

FEATURES 26th Conference Preview, Denver ...... 434 Calendar ...... 436 Program...... 438 Registration Form...... 442 Measuring and Predicting Perceived Audio Quality...... 443

DEPARTMENTS

Reviews of Acoustical Patents...... 432 Available Literature...... 457 News of the Sections...... 449 Membership Information...... 459 Upcoming Meetings ...... 454 Advertiser Internet Directory...... 461 Sound Track ...... 455 Sections Contacts Directory ...... 465 New Products and Developments...... 456 AES Conventions and Conferences ...... 472 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 53 NUMBER 6 2005 JUNE CONTENTS PAPERS Low Peak Amplitudes for Group Additive Synthesis ...... Andrew Horner and Simon Wun 475 Optimizing wavetable synthesis for maximum signal-to-noise ratio should take advantage of manipulating the phase of the components in order to reduce the peak amplitude for a given spectrum. This paper compares various phase selection methods on group additive synthesis, a special case of multiple wavetable synthesis, where each wavetable contains a distinct subset of the harmonics. Group additive synthesis peak factors are up to 30% worse than their counterparts, unless wavetable matching and peak-factor optimization are integrated. The genetic algorithm and simulated annealing methods get the best performance out of both multiple wavetable synthesis and group additive synthesis.

ENGINEERING REPORTS Reconstruction of Recorded Sound from an Edison Cylinder Using Three-Dimensional Noncontact Optical Surface Metrology ...... Vitaliy Fadeyev, Carl Haber, Christian Maul, John W. McBride, and Mitchell Golden 485 Audio information stored in the undulations of a groove in a mechanical sound carrier, such as a cylinder or disk phonograph record, may be reconstructed, without contact, by measuring the groove shape and position using precision optical metrology methods and digital image processing. This report describes the first three- dimensional reconstruction of recorded sound from a mechanical carrier using this approach. The source material, a celluloid Edison cylinder, was scanned using color-coded confocal microscopy techniques. The results and prospects of this approach are discussed. Large-Signal Analysis of Class A Vacuum Triode Push–Pull Output Stage ...... Muhammad Taher Abuelma'atti 509 A mathematical model of the transfer function of class A push–pull triode vacuum tube amplifiers yields closed-form series expressions for the amplitudes of output spectral components. The results are similar to those of a transistor class A output stage, containing odd-order harmonics and intermodulation components. For small amplitude signals, the degrading components are very small; they monotonically increase with large input tones. The parameters of the model can readily be determined using simple calculations. Servo Control of Loudspeaker Cone Motion Using an Optical Linear Displacement Sensor ...... W. Geiger 518 Large signals in a loudspeaker produce distortion because of nonlinear force factors and changing stiffness. Both effects can be reduced by a classical feedback loop that uses optical means to sense the displacement and cone motion. By sensing the actual location of the cone structure, feedback linearizes the system without requiring a detailed model to precompensate for nonideal mechanical properties. In addition, the feedback system can improve the magnitude and phase versus frequency.

LETTERS TO THE EDITOR Comments on “Analysis of a Folded Acoustic Horn” ...... Earl Geddes 525 Authors’ Reply ...... Andrew Bright, Keith Holland, and Frank J. Fahy 526

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 528 Care and handling of magnetic tape; overview of AES standards

FEATURES 27th Conference Preview, Copenhagen ...... 532 Calendar ...... 534 Program...... 536 Registration Form...... 540 Automotive Audio Quality...... 542

DEPARTMENTS News of the Sections...... 549 Membership Information...... 561 Upcoming Meetings ...... 554 Advertiser Internet Directory...... 563 Sound Track ...... 555 In Memoriam ...... 568 New Products and Developments...... 557 Sections Contacts Directory ...... 569 Available Literature...... 558 AES Conventions and Conferences ...... 576 p.578_TOC 8/2/05 3:15 PM Page 1

JOURNAL OF THE AUDIO ENGINEERING SOCIETY AES AUDIO/ACOUSTICS/APPLICATIONS VOLUME 53 NUMBER 7/8 2005 JULY/AUGUST CONTENTS PAPERS High-Efficiency Low-Bl Loudspeakers ...... Ronald M. Aarts 579 As a critical design parameter of loudspeakers, especially at low frequencies, the force factor (Bl) determines the efficiency, impedance, sound level, temporal response, weight, and cost. High-Bl drivers have good efficiency but require large magnet systems. An alternative approach, which yields much lower cost and weight while preserving efficiency, uses low-Bl drivers. Prototype drivers with moving magnets and stationary coils were evaluated in a limited frequency range where efficiency is highest. This approach is suited to small portable loudspeakers. Discrimination of Group Delay in Clicklike Signals Presented via Headphones and Loudspeakers ...... Sheila Flanagan, Brian C. J. Moore, and Michael A. Stone 593 The threshold for detecting a frequency-dependent group delay in a clicklike sound was found to be independent of the center frequency of the delay (1-4 kHz) and was about 2 ms for presentation via headphones, or via loudspeakers in a nonreverberant room, for both binaural and monaural listening. In a reverberant room, thresholds increased, especially at low frequencies. These results suggest that the nonlinear phase response of loudspeakers is unlikely to have any audible effect in typical rooms. A Simple Hybrid Approach to the Time-Scale Modification of Speech ...... Don Knox, Nicholas Bailey, and Iain Stewart 612 Time-domain methods for stretching speech usually produce stuttering and roughness artifacts from mismatches at signal segment boundaries, especially with time-stretch ratios greater than 1.3. By combining time-domain and analysis-synthesis methods, a simple hybrid approach greatly reduced such artifacts at ratios greater than 1.6. Formal listening tests demonstrate an improvement in speech quality without incurring the complexity burden of full analysis-synthesis methods. The hybrid algorithm counters spectral mismatch and transient repetition. ENGINEERING REPORTS Directivity of Artificial and Human Speech ...... Teemu Halkorsaari, Markus Vaalgamaa, and Matti Karjalainen 620 Having an artificial mouth with the same radiating characteristics of real speakers provides a useful working tool for telecommunications research. Responses to three mouth simulators were compared to that of a group of test subjects in order to evaluate their similarity. More than 10 dB of difference was discovered in the two cases. The main contributors to the human radiating characteristics are mouth aperture size and effects of the upper body. LETTERS TO THE EDITOR Comments on “Low-DC-Resistance, Low-Frequency Loudspeaker Enclosures”.....Alex de Koster 632 Author’s Reply ...... Carlo Zuccatti 632 CORRECTIONS Correction to “Low-DC-Resistance, Low-Frequency Loudspeaker Enclosures” ...... Carlo Zuccatti 632 STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 633 High-resolution multichannel digital interface (HRMAI); digital measurements; digital interfacing; file transfer; transfer technologies; microphones; listening tests FEATURES 118th Convention Report, Barcelona...... 642 Exhibitors ...... 658 Program...... 661 119th Convention Preview, New York ...... 714 Exhibit Previews ...... 716 High-Density Optical-Disk Formats ...... 749 High-Resolution Audio in an Age of Universal Playback...... 754 DEPARTMENTS Reviews of Acoustical Patents...... 636 Membership Information...... 765 News of the Sections...... 756 Advertiser Internet Directory...... 767 Sound Track ...... 762 In Memoriam ...... 775 Upcoming Meetings ...... 763 Sections Contacts Directory ...... 777 Available Literature...... 763 AES Conventions and Conferences ...... 784 p.786_TOCpat 8/31/05 2:39 PM Page 1

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CONTENTS

PAPERS Directional Measurement of Airborne Sound Transmission Paths Using a Spherical Microphone Array...... Bradford N. Gover 787 A spherical microphone array with its narrow beam can be used as a measurement tool to isolate sound leakage between adjoining rooms. Finding weak spots in the separating walls provides a diagnostic means for improving sound isolation. Such weak spots as slits and partial holes were identified in both controlled laboratory situations and real buildings. Minor defects of only a few decibels could be detected. Decomposition of Impulse Responses Using Complex Wavelets...... S. J. Loutridis 796 The continuous wavelet transform converts a one-dimensional audio signal into a two-dimensional presentation, thereby providing more insight into its time–frequency structure. It is especially well suited for the analysis of transient signals. By optimizing the bandwidth of the wavelet filter bank, the impulse response of a loudspeaker, or a room, reveals resonances, coloration, and other problems that would otherwise be hidden. The wavelet transform can be used for envelope extraction, calculation of instantaneous frequency, and power spectral density. Optimal Design and Synthesis of Reverberators with a Fuzzy User Interface for Spatial Audio ...... Mingsian R. Bai and Ganyuan Bai 812 Reverberator architectures, even when capable of achieving high quality, often have dozens of parameters that must be hand adjusted in order to create natural sounding space. To minimize the effort of trial and error in parameter tuning, an automatic search procedure based on genetic algorithms is recommended. A fuzzy logic and graphic user interface was also developed to facilitate users in selecting their favorite room sound. Subjective tests confirmed the quality of the resulting reverberation.

ENGINEERING REPORTS Evaluation of Iterative Methods for Wavetable Matching ...... Simon Wun and Andrew Horner 826 The noniterative approach to wavetable matching produces good results but the computation grows exponentially, whereas the iterative approach is less robust while computation only grows linearly. Several new iterative methods are proposed in order to achieve better quality without excessive computation. This paper describes wavetable matching using iterative enumeration, iterative local search, and seeded iterative local search. Results confirm that there are numerous near optimal wavetable matches.

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 836 High-performance serial bus (IEEE 1394); Internet audio quality; forensic audio; loudspeaker measurement and modeling; acoustics and sound-source modeling

FEATURES 26th Conference Report, Denver...... 838 Digital Music Notation Formats...... 849 120th Convention, Paris, Call for Papers...... 880

DEPARTMENTS News of the Sections...... 855 Membership Information...... 868 Upcoming Meetings ...... 862 Advertiser Internet Directory...... 871 Sound Track ...... 863 In Memoriam ...... 879 New Products and Developments...... 865 Sections Contacts Directory ...... 881 Available Literature...... 867 AES Conventions and Conferences ...... 888 p.890_TOC 10/6/05 11:44 AM Page 1

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PAPERS Long Interpolation of Audio Signals Using Linear Prediction in Sinusoidal Modeling ...... Mathieu Lagrange, Sylvain Marchand, and Jean-Bernard Rault 891 A new synthesis technique, based on linear prediction of sinusoidal parameters, is proposed as a means to interpolate missing audio in gaps lasting as long as one second. Recreated musical partials include the expected vibrato and tremolo, thereby creating a natural sound for complex polyphonic signals. This parametric approach is an improvement over the more common methods of sinusoidal and temporal interpolation. Subjects judged the result as being a higher quality. Development and Evaluation of a Model for Predicting the Audibility of Time-Varying Sounds in the Presence of Background Sounds ...... Brian R. Glasberg and Brian C. J. Moore 906 A model for predicting the audibility of a target signal in the presence of a noisy background can be applied to many stimuli, such as announcement signals in aircraft or trains and ring tones of mobile telephones in urban environments. Rather than using a model that assumes steady state, this study considers time-varying signals and background sounds, which have more applications to real situations. However, the complexity of informational masking makes the problem more difficult. Directional Resolution of Head-Related Transfer Functions Required in Binaural Synthesis ...... Pauli Minnaar, Jan Plogsties, and Flemming Christensen 919 When a signal recorded in an anechoic environment is convolved with a pair of head-related transfer functions (HRTFs), the listener experiences a sound source in a virtual space. An infinite number of HRTFs are needed to represent all possible locations. Interpolation among a limited number of HRTFs greatly reduces the need for a complete set, but such an approach assumes knowledge of the spatial resolution of the set and the accuracy of the resulting interpolation. In this study the spatial resolution of the basis set was determined to produce interpolated results that were subjectively identical to actual HRTFs. New Type of Acoustic Filter Using Periodic Polymer Layers for Measuring Audio Signal Components Excited by Amplitude-Modulated High-Intensity Ultrasonic Waves ...... Minoru Toda 930 Because of nonlinearity in acoustic wave propagation, audio frequencies can be generated by strong ultrasonic signals. For example, two signals closely spaced in frequency create an audio signal at the difference frequency as if air were a demodulator. Measuring these demodulation products is difficult because the nonlinearity of microphones also produces similar signals. A new type of acoustic filter using periodic polymer layers greatly reduced the influence of the microphone by providing an acoustic low-pass function. In this paper a detailed theory for multilayer films as a filter confirms the approach.

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 942 Tape care and handling; audio preservation and restoration; library and archive systems; audio metadata; audio connectors

FEATURES Program Loudness Revisited ...... 945 The Evolving World of Film Sound ...... 951 New Officers 2005/2006...... 954 Review of Society’s Sustaining Members ...... 958 120th Convention, Paris, Call for Papers...... 992

DEPARTMENTS News of the Sections...... 978 Membership Information...... 986 Sound Track ...... 982 Advertiser Internet Directory...... 989 New Products and Developments...... 983 In Memoriam ...... 991 Available Literature...... 984 Sections Contacts Directory ...... 993 Upcoming Meetings ...... 985 AES Conventions and Conferences ...... 1000 p.1002_TOC.qxd 11/15/05 10:41 AM Page 1

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CONTENTS

President’s Message ...... Neil Gilchrist 1003

PAPERS Three-Dimensional Surround Sound Systems Based on Spherical Harmonics ...... M. A. Poletti 1004 Based on spherical harmonics, this paper reviews and extends the three-dimensional theory of sound recording and reproduction. Three methods of recording are compared: free-space directional microphone arrays, pressure microphones mounted in a sphere, and free-space arrays with variable radii. An analysis shows that appropriate sound fields can be created without the requirement of dipole loudspeakers. In addition, mode matching can be extended to reverberant environments with nonideal loudspeakers. High-Order Digital Parametric Equalizer Design ...... Sophocles J. Orfanidis 1026 Unlike classical equalizers having first- or second-order filters, using higher order Butterworth, Chebyshev, and elliptic analog prototypes provides flatter passbands and sharper band edges. The analysis shows their advantages. Equalizer coefficients are computed using center frequency, peak gain, bandwidth, and bandwidth gain. The discussions on topology explore transposed, normalized-lattice, and minimum roundoff noise state-space realizations. Design methods apply equally well to low-pass and high-pass shelving filters and to ordinary bandpass and bandstop filters. Stability and Sensitivity Analyses for Diffusers with Single and Multiple Active Elements ...... Mark R. Avis, Lejun Xiao, and Trevor J. Cox 1047 Passive diffusers are used to improve spatial acoustics, but they are limited to mid and high frequencies because of the required depth. Alternatively, by actively controlling the surface impedance with an electronic control system, reflected wave fronts can be dispersed. While active impedance technology has usually been used to absorb sound and cancel noise, it can also be used for sound dispersion. Active diffusers are more difficult to use than active absorbers because of tighter requirements on system accuracy. Test results confirm that the stability of a real system is consistent with the theoretical analysis and that active diffusers are prone to instability.

ENGINEERING REPORTS Acoustic Analysis and Design of Miniature Loudspeakers for Mobile Phones ...... Mingsian R. Bai and Jerwoei Liao 1061 Increasing needs for audio quality in miniature loudspeakers used in mobile phones require tradeoffs not found in conventional large loudspeakers. Miniature loudspeakers have a smaller Bl product, which influences the high-frequency rolloff and sensitivity. An electroacoustic analysis explores a model of the duct structure and head diffraction effects. An acoustic design to extend the low-frequency bandwidth is suggested to increase perceived quality. Large-signal performance appears to be a critical issue.

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 1078 Recoding data set for audio bit-rate reduction; digital input/output interfacing; audio connectors; grounding and EMC; storage and handling of media

FEATURES Loudspeaker Array Technology ...... 1081 28th Conference, Piteå, Sweden, Call for Papers ...... 1104

DEPARTMENTS News of the Sections...... 1085 Advertiser Internet Directory...... 1099 Sound Track ...... 1092 In Memoriam ...... 1102 Upcoming Meetings ...... 1092 AES Annual Report ...... 1103 New Products and Developments...... 1093 Sections Contacts Directory ...... 1105 Available Literature...... 1094 AES Conventions and Conferences ...... 1112 Membership Information...... 1095 Dec_TOC.qxd 12/20/05 12:01 PM Page 1

JOURNAL OF THE AUDIO ENGINEERING SOCIETY AUDIO/ACOUSTICS/APPLICATIONS KEE HIG AVOLUME 53E NUMBERS 12 2005 DECEMBER # TO CONTENTS LAS PAPERS Spatial Impulse Response Rendering I: Analysis and Synthesis...... Juha Merimaa and Ville Pulkki 1115 A new processing technique, called spatial impulse response rendering, allows a measured room response to be reproduced using an arbitrary multichannel loudspeaker system. An intermediate representation based on perceptually motivated attributes was derived from the microphone signals—such as from a B-format microphone—and using a convolving reverberator, this representation was then transformed into the loudspeaker signals of the specified configuration. This analysis–synthesis approach used psychophysical rather than physical accuracy. Based on energy analysis, the time-dependent direction of arrival and diffuseness of the room response was analyzed within frequency bands. Perception of Modal Distribution Metrics in Critical Listening Spaces—Dependence on Room Aspect Ratios...... B. M. Fazenda, M. R. Avis, and W. J. Davies 1128 To minimize the influence of low-frequency resonances in small listening rooms that are used for monitoring, designers sometimes optimize the aspect ratio to control the location of resonances. Such optimizations are based on a figure of merit that considers the modal distribution of resonances. Using three virtual rooms, which scored at the extremes of these metrics, the utility of these metrics was examined. The results showed that ranking of rooms was misleading because of a strong dependence on spectral content of the program material. Regardless of the statistics of modal resonances, if the program excited a resonance, it was perceived. Artificial Reverberation Control Using Cepstrum Decomposition While Maintaining Locations of Peaks and Dips on the Frequency Responses ...... Yoshinori Takahashi and Mikio Tohyama 1142 Rendering and morphing the room reverberation characteristics is a key component for modeling acoustic events in a virtual space. Rather than use the typical techniques for changing the response, the authors propose a modification of a reference response as a means for changing spatial properties. By increasing or decreasing the peaks and valleys in the frequency response, the effective reverberation time in a given frequency band is correspondingly modified. Hence, the personality of the room is preserved even as the response is morphed. ENGINEERING REPORTS Subjective Testing of Compression Drivers...... Earl R. Geddes, Lidia W. Lee, and Roberto Magalotti 1152 Although it is known that compression drivers produce both linear and nonlinear distortion, engineers assume that both of these degradations are audible and must therefore be minimized. However, a double-blind subjective test showed that listeners could not detect nonlinear distortion. Rather, only linear distortions (differences in frequency response) were significant. This unexpected result has implications for designers who are maximizing perceived quality while minimizing manufacturing cost. STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 1163 Forensic audio; digital audio in ATM networking; ATM over Ethernet; digital audio measurements; audio file exchange; audio over IEEE1394; acoustics and sound source modeling FEATURES 27th Conference Report, Hillerød, Denmark ...... 1166 119th Convention Report, New York ...... 1174 Exhibitors ...... 1190 Technical Program...... 1196 Audio Processing for the Hearing Impaired...... 1242 Education News...... 1251 Call for Nominations for the Board of Governors...... 1258 Call for Awards Nominations...... 1259 28th Conference, Piteå, Sweden, Call for Papers ...... 1267 Bylaws: Audio Engineering Society, Inc...... 1269 Index to Volume 53 ...... 1273 DEPARTMENTS Reviews of Acoustical Patents...... 1158 Available Literature...... 1256 News of the Sections...... 1247 Advertiser Internet Directory...... 1257 Upcoming Meetings ...... 1250 Membership Information...... 1260 Sound Track ...... 1253 Sections Contacts Directory ...... 1289 New Products and Developments...... 1255 AES Conventions and Conferences ...... 1296 J-F2006_TOC.qxd 2/1/06 4:22 PM Page 1

JOURNAL OF THE AUDIO ENGINEERING SOCIETY AUDIO/ACOUSTICS/APPLICATIONS KEE HIG AVOLUME 54E NUMBERS 1/2 2006 JANUARY/FEBRUARY # TO CONTENTS LAS PAPERS Spatial Impulse Response Rendering II: Reproduction of Diffuse Sound and Listening Tests ...... Ville Pulkki and Juha Merimaa 3 A proposed technique for spatial impulse response rendering, called SIRR, introduced in a previous article, is examined and evaluated in two listening tests. Based on the analysis presented, a hybrid method consisting of amplitude panning at low frequencies and phase randomization at high frequencies was implemented. In the first test, conducted in an anechoic chamber, the SIRR technique performed best in reproducing a reference virtual reality. In the second test, measured responses of existing spaces were reproduced with SIRR and other techniques. SIRR reproduction was judged most natural, especially at off-center listening. A Hybrid Time–Frequency Domain Approach to Audio Time-Scale Modification ...... David Dorran, Robert Lawlor, and Eugene Coyle 21 Increasing or decreasing audio delivery rate without changing the pitch can be achieved by processing the audio in either the frequency or time domain. While time-domain approaches are both efficient and without artifacts, they require the presence of a strong quasi-periodic component. In contrast, frequency-domain approaches work over a wide range of signal types but tend to produce reverberantlike artifacts. A new hybrid approach combines the advantages of both approaches, especially for speech, without requiring an a priori knowledge of the signal. Effects of Headtracker Latency in Virtual Audio Displays ...... Douglas S. Brungart, Alex J. Kordik, and Brian D. Simpson 32 In the design of headtracked virtual auditory displays, the latency between head movement and the corresponding image shift can be extremely critical. A series of experiments showed that latency of about 70 ms begins to impair localization ability and becomes noticeable to the listener. While this threshold varies among listeners and types of audio signals, it suggests that headtracker latency is generally not a limiting factor for creating a quality image in state-of-the-art audio display systems, which typically exhibit latency values of less than 30 ms. ENGINEERING REPORTS Active All-Pass Crossover Networks with Equal Resistors and Equal Capacitors ...... René Christensen 45 Active crossover networks can be constructed with all-pass functions and with the additional constraint that resistors and capacitors have the same value. Two such networks are examined: a fourth-order three-way filter and a sixth-order four-way filter. While the transient responses are not perfect, compared to the familiar Linkwitz–Riley configuration, the group delays are significantly smoother for filters of the same order. CORRECTIONS Correction to “Spatial Impulse Response Rendering I: Analysis and Synthesis” ...... Juha Merimaa and Ville Pulkki 54

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 55 Life expectancy of MO and recordable compact discs; unique identifiers in AES3; loudspeaker measurements FEATURES Audio Forensics...... 56 Audio Networking: Applications and Requirements...... Kevin Gross 62 Reprint of “Speech Reinforcement in St. Paul’s Cathedral” ...... P. H. Parkin and J. H. Taylor 67 29th Conference, Seoul, Call for Papers...... 95 121st Convention, San Francisco, Call for Papers ...... 96 DEPARTMENTS News of the Sections...... 76 Membership Information...... 87 Sound Track ...... 80 Advertiser Internet Directory...... 91 Upcoming Meetings ...... 82 Sections Contacts Directory ...... 97 New Products and Developments...... 82 AES Conventions and Conferences ...... 104 Available Literature...... 83 p.106_TOC_Mar.qxd 3/2/06 2:51 PM Page 1

JOURNAL OF THE AUDIO ENGINEERING SOCIETY AUDIO/ACOUSTICS/APPLICATIONS KEE HIG AVOLUME 54E NUMBERS 3 2006 MARCH # TO LAS CONTENTS

PAPERS Modulation and System Techniques in PWM and SDM Switching Amplifiers...... Malcolm Hawksford 107 Switching amplifiers that use either sigma–delta modulation (SDM) or pulse-width modulation (PWM) can be modeled in terms of linear angle modulation. Distortion generated when applying feedback to PWM is demonstrated, and strategies to improve linearity are then presented. Also, a look-ahead SDM incorporating an energy-balancing binary decision threshold is examined. A unified analytic approach shows that SDM can compete in terms of linearity with PWM power amplifiers and that energy-balancing SDM can achieve similar peak signals. A Search for Best Error Metrics to Predict Discrimination of Original and Spectrally Altered Musical Instrument Sounds...... Andrew B. Horner, James W. Beauchamp, and Richard H. Y. So 140 Knowing the required accuracy of harmonic components in decoded or synthesized periodic audio signals allows a designer to select an optimum strategy. An error metric of spectral accuracy was proposed and evaluated in subjective listening tests. Listeners were asked to discriminate sounds with randomly altered changes in spectral amplitude without any changes in the average spectrum or overall loudness. These tests confirmed the validity of the model. Advanced Simulation of a Condenser Microphone Capsule ...... Roger S. Grinnip III 157 An advanced model of a pressure condenser microphone capsule was used to simulate the performance of an experimental prototype. The external acoustic domain was modeled using the boundary-element method, which allowed the capsule to have an arbitrary shape. The results show excellent agreement throughout the measured frequency range. This coupled model was better than the conventional lumped-element techniques. Bit-Rate Scalable Intraframe Sinusoidal Audio Coding Based on Rate-Distortion Optimization ...... Richard Heusdens, Jesper Jensen, W. Bastiaan Kleijn, Valery Kot, Omar A. Niamut, ...... Steven van der Par, Nicolle H. van Schijndel, and Renat Vafin 167 A parametric coder based on rate-distortion optimal sinusoid + noise coding of audio and speech signals is presented. The coder minimizes a perceptual distortion measure subject to a bit-rate constraint. A variable-length signal analysis is used to avoid preechoes and to reduce the intersegment correlation. Frequency differential coding is performed to exploit intrasegment correlations. In subjective listening tests using music and speech, this method often performed better than state-of-the-art MPEG-4 audio coders.

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 189 ATM networking; digitally-interfaced microphones; microphone specifications; Standards meetings

FEATURES 12th Tokyo Regional Convention Report...... 190 Exhibitors ...... 194 Program...... 196 120th Convention Preview, Paris...... 208 Exhibit Previews ...... 210 Stereophonic Recording Techniques: Old Challenges, New Approaches...... 225 29th Conference, Seoul, Call for Papers...... 247 121st Convention, San Francisco, Call for Papers ...... 248

DEPARTMENTS News of the Sections...... 230 Advertiser Internet Directory...... 239 Upcoming Meetings ...... 233 In Memoriam ...... 245 Sound Track ...... 234 Sections Contacts Directory ...... 249 Available Literature...... 236 AES Conventions and Conferences ...... 256 Membership Information...... 238 p.258_TOC_Apr.qxd 4/4/06 11:52 AM Page 1

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PAPERS A Hybrid Technique for Validating Unidimensionality of Perceived Variation in a Spatial Auditory Stimulus Set ...... Tobias Neher, Tim Brookes, and Francis Rumsey 259 Having a set of audio stimuli that varies along a specified single perceptual dimension, regardless of variations in physical acoustic parameters, would be extremely useful in subjective experiments that require training or reference stimuli. After considering various paradigms for validating such a set, a hybrid technique comprising multidimensional scaling and subject-specific verbalizations proved to be the most promising. This technique was developed further and experiments demonstrated that it revealed which groups of stimuli vary as intended along a single perceptual dimension and which vary along multiple dimensions. Spatially Modulated Auditory Alerts for Aviation ...... Durand R. Begault, Mark R. Anderson, and Bryan U. McClain 276 Detection of a nonspeech auditory alert (alarm) in a noisy environment increases when such an alert is moved along a virtual spatial trajectory using a 3-D auditory display. This approach decreases thresholds by as much as 8 dB because of dynamic changes in level and interaural cross-correlation of the signals at the two ears.

ENGINEERING REPORTS Dynamic Crosstalk Cancellation for Binaural Synthesis in Virtual Reality Environments ...... Tobias Lentz 283 In order to create a 360-degree virtual reality with free listener movement, a system was designed with a combination of dynamic head-tracking crosstalk cancellation and binaural synthesis of spatial environments. Rather than use two loudspeakers with limited rotational range, the proposed system uses two pairs of loudspeakers with dynamic crossfading as the listener rotates his head through eight sectors. Preliminary tests in an environment with reflections demonstrate the feasibility of the approach. Model Optimization of Distributed-Mode Loudspeaker Using Attached Masses ...... Suzhen Zhang, Yong Shen, Xiaoxiang Shen, and Jinglei Zhou 295 While distributed-mode loudspeakers have many advantages compared with conventional cone topology, they usually have excessive fluctuation in frequency response. By attaching area masses, resonances in selective frequency regions can be distributed more evenly, and the excessive fluctuation is reduced. A generic algorithm has been developed to optimize the position, weight, and number of such masses. Simulated results using FEMLAB were experimentally tested in an anechoic chamber, thus validating the approach to improving distributed-mode topologies.

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 306 Unique identifiers in AES3; audio in ATM networks; audio metadata; forensic audio

FEATURES 28th Conference Preview, Piteå, Sweden ...... 308 Calendar ...... 311 Program...... 312 Audio Power Amplification ...... 319 30th Conference, Saariselkä, Finland, Call for Papers...... 336

DEPARTMENTS News of the Sections...... 324 Membership Information...... 334 Upcoming Meetings ...... 328 Advertiser Internet Directory...... 335 Sound Track ...... 329 Sections Contacts Directory ...... 337 New Products and Developments...... 331 AES Conventions and Conferences ...... 344 Available Literature...... 332 p.346_TOC_May.qxd 5/2/06 10:57 AM Page 1

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AVOLUME 54E NUMBERS 5 2006 MAY O

CONTENTS

PAPERS Low-Frequency Optimization Using Multiple Subwoofers...... Todd Welti and Allan Devantier 347 The acoustic environment of a sound system has a strong influence on the sound quality at low frequencies, especially in small spaces. As a result there is an interest in solutions that improve the performance. While conventional approaches tend to focus on signal processing, the proposed solution introduces the location of subwoofers as the major variable, with the addition of minimal signal processing. Using a metric that optimizes performance in multiple seats, a robust solution becomes available. Identification of Quality Attributes of Spatial Audio by Repertory Grid Technique ...... Jan Berg and Francis Rumsey 365 In order to evaluate spatial quality of audio reproduction, it is first necessary to select a method that can identify the relevant attributes. Being a relatively new field, spatial audio does not yet have a well-established list of such attributes. As an extension of the work of Kelly, the authors apply the repertory grid technique, which is based on subjects’ personal reflections of the stimuli. Because subjects describe the way in which triads of stimuli differ, the attributes are elicited rather than constructed by the experimenter. The results are consistent with the findings from other methods utilized, thus demonstrating the validity of this approach when used in spatial audio. Conversion of Discretely Sampled Sound Field Data to Auralization Formats ...... Bård Støfringsdal and U. Peter Svensson 380 Sound field simulations often use finite-element or other mesh-based methods, which produce output data that must first be converted to an intermediate format in order to be compatible with conventional auralization techniques. The proposed method converts sampled mesh data to a series of plane waves using a circular array of virtual sources. While not a perfect conversion of an arbitrary sound field, this approach provides a stable frequency-domain representation which minimizes the error in a least squares sense. Such reproduction errors should be acceptable in most practical cases. Results for two dimensions are readily extensible to three dimensions. Compensating the Response of Near-Field Loudspeaker Monitors to Minimize the Effects of Desktop Acoustic Loading ...... Andrew Goldberg, Aki Mäkivirta, and Ari Varla 401 When two-way loudspeakers are mounted on or near mixing consoles, acoustical loading detrimentally changes the response. Acoustical loading systematically raises the response in the 100- to 250-Hz region, and reflections at mid and high frequencies make a comb filtering effect. In an extensive study, 80% of the cases exhibited low-frequency one-sixth octave peaks of about 4 to 6 dB. A single second-order notch filter, appropriately designed, removes much of the negative effects of nearby mixing consoles, desktops, and work surfaces. LETTERS TO THE EDITOR Comments on “Perception of Modal Distribution Metrics in Critical Listening Spaces— Dependence on Room Aspect Ratios”...... Earl Geddes 412 Authors’ Reply ...... B. M. Fazenda, M. R. Avis, and W. J. Davies 412

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 414 Audio file format for interchange; high-resolution multichannel audio interconnection (HRMAI)

FEATURES Automotive Audio Update...... 416 Loudness Trumps Everything ...... 421 30th Conference, Saariselkä, Finland, Call for Papers...... 440

DEPARTMENTS News of the Sections...... 424 Membership Information...... 431 Sound Track ...... 428 Advertiser Internet Directory...... 437 New Products and Developments...... 429 Sections Contacts Directory ...... 441 Upcoming Meetings ...... 429 AES Conventions and Conferences ...... 448 Available Literature...... 430 p450_revisedTOC_June.qxd 6/7/06 11:38 AM Page 1

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CONTENTS

PAPERS Loudspeakers and Rooms for Sound Reproduction—A Scientific Review...... Floyd E. Toole 451 Much of our understanding of how listeners hear spatial acoustics originates from studies with large spaces, notably concert halls. While the resulting insights are frequently extended to small spaces, other phenomena weaken the validity of conclusions. Listeners may be adapting to the complexities of reflections and resonances in small spaces, thereby reducing or eliminating the perception of measured degradation. Informal evidence from the professional recording industry suggests that humans compensate and adapt to the acoustical anarchy of complex sound fields. A Comparison of the “Pruned Tree” versus “Stack” Algorithms for Look-Ahead Sigma–Delta Modulators...... J. A. S. Angus 477 High-order Sigma–Delta modulators, used in high-quality converters, cannot use aggressive noise-shaped filtering because the one sample delay in the feedback produces instability under overload conditions. Various solutions have been proposed, but computational burdens grow exponentially with increases in the look-ahead depth. Pruning the choices reduces the burden but at the risk of discarding the optimum choice. A comparison of the “pruned tree” and the “stack” algorithms shows that the former is most efficient even though the latter has better theoretical performance. Evaluation of Sound Quality, Boominess, and Boxiness in Small Rooms ...... Adam Weisser and Jens Holger Rindel 495 Subjective listening tests were conducted in seven small rooms to investigate those physical attributes that correspond to the perception of boominess and boxiness. Three new acoustic metrics—small room bass ratio, small room early decay time ratio, and low–high ratio—proved to be better predictors of sound quality than conventional measures. However, the type of audio, namely music or speech, influenced preference and quality judgments. Speech was best in rooms with weak reverberation, whereas a preferred range of reverberation was found for music.

ENGINEERING REPORTS Effect of Reflectors on Sound-Source Localization with Two Microphones ...... Sandeep A. Phatak, Rama Ratnam, Bruce C. Wheeler, William D. O’Brien, Jr., and Albert Feng 512 The performance of algorithms that extract source location using a pair of microphones degrades in either reverberant conditions or the presence of parallel reflectors. Localization of signals such as white noise, which are very broadband, is more robust than with speech, which can be narrow band. Reverberation produces excessive temporal smearing at low frequencies. Finally, the localization–extraction algorithm, which is frequency-based, proved more reliable than the commonly used multiple signal classification algorithm.

FEATURES 29th Conference Preview, Seoul ...... 526 Calendar ...... 528 Program...... 530 Registration Form...... 535 Enhanced Multichannel Audio ...... 536 Surround Sound: A Chance for Enhanced Creativity ...... 540

DEPARTMENTS News of the Sections...... 542 Upcoming Meetings ...... 550 Sound Track ...... 546 Membership Information...... 551 New Products and Developments...... 548 Sections Contacts Directory ...... 560 Available Literature...... 549 AES Conventions and Conferences ...... 568 Advertiser Internet Directory...... 549 JOURNAL OF THE AUDIO ENGINEERING SOCIETY AUDIO/ACOUSTICS/APPLICATIONS

AVOLUME 54E NUMBERS 7/8 2006 JULY/AUGUST

CONTENTS PAPERS A Robust and Computationally Efficient Speech/Music Discriminator ...... Jayme Garcia Arnal Barbedo and Amauri Lopes 571 Discriminating between speech and music is critical in such applications as speech recognition and automatic music transcription. A new method for achieving discrimination, which is computationally simple, attains almost perfect performance on a wide range of samples. The strategy uses four features extracted from frame histograms: zero-crossing rate, spectral rolloff, perceived loudness, and fundamental frequencies. Modest latency allows the strategy to be used in real-time applications. Vibrations of Loudspeaker Cones in the Transitional Range...Zhi-Liang Zhang and Chang-Jun Cheng 589 Loudspeaker diaphragm vibrations are analyzed in the transitional frequency region where bending waves are beginning to play a significant role in relation to the longitudinal motion. An analytic and numeric analysis shows that the two types of motion are highly coupled. The first nonbending frequency can be considered to be the upper limit of the loudspeaker’s frequency response. Real-Time Processing of Image Sources Using Binary Space Partitioning ...... Dirk Schröder and Tobias Lentz 604 Unlike the acoustic simulation of virtual spaces for static environments, with fixed source and listener locations, interactive virtual reality requires the aural experience to match a dynamically changing visual scene. Rapid computations are therefore more important than detailed acoustic modeling of a space. In the approach the geometry of a scene is subdivided into small subdivisions and pre-encoded in optimized data structures, BSP trees, with image source data.

ENGINEERING REPORTS Cumulative Spectral Analysis for Transient Decaying Signals in a Transmission System Including a Feedback Loop ...... Yoshinori Takahashi, Mikio Tohyama, and Yoshio Yamasaki 620 Determining the principle resonant frequency of a public address system before the beginning of howling is a valuable tool. By introducing a spectral accumulation function into the previously known technique of cumulative spectral analysis (used with loudspeakers), potential resonant frequencies are more clearly revealed even when they are only barely audible. When applied to the decaying portion of a speech signal, the display clearly predicts the principle resonance. Effectively, the technique increases the order of resonant poles.

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 630 True peak metering; digital interface for microphones; ATM network over Ethernet; IEEE 1394 use cases; digital audio measurements; digital audio input-output interfaces; audio-file transfer and exchange; transfer technologies

FEATURES 120th Convention Report, Paris ...... 642 Exhibitors...... 660 Program ...... 663 121st Convention Preview, San Francisco...... 742 Exhibit Previews...... 744 Digital Radio Broadcasting...... 771

DEPARTMENTS Reviews of Acoustical Patents...... 636 Membership Information...... 785 News of the Sections...... 775 Advertiser Internet Directory...... 787 Sound Track ...... 781 Sections Contacts Directory ...... 792 Available Literature...... 782 AES Conventions and Conferences ...... 800 Upcoming Meetings ...... 784 p802_TOC_Sept.qxd 8/23/06 10:05 AM Page 1

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AVOLUME 54E NUMBERS 9 2006 SEPTEMBER CONTENTS PAPERS Perception and Analysis of Selected Auditory Events with Frequency-Dependent Directions ...... Toni Hirvonen and Ville Pulkki 803 A study of a single auditory event created by an array of 11 loudspeakers distributed along the azimuth revealed some new information on the perception of source width and sound location. The source location with highest and lowest frequencies dominates the perceived distribution of sound, and frequency bands were also spatially integrated to a narrower perceived source than in reality. With click stimulus, the source was perceived very narrow, although the clicks were distributed widely around the listener. The traditional cross-correlation model was tested with the stimuli, and the results did not match the perceived auditory objects in general. Extraction of Auditory Features and Elicitation of Attributes for the Assessment of Multichannel Reproduced Sound...... Sylvain Choisel and Florian Wickelmaier 815 Although there is extensive research on the auditory features of multichannel sound reproduction, scientists are still examining the philosophical and practical issues of various methods. A new approach, perceptual structure analysis, is based on subjective evaluation of triads of sounds without first requiring verbal descriptors, unlike the more traditional repertory grid technique. By testing the consistency of the judgments, it is possible to assess the listener's ability to identify the features. While a conclusive comparison of the attributes obtained by the two elicitation methods would require a larger number of participants, it was possible to derive a common set of eight attributes. Frequency-Domain Algorithms for Audio Signal Enhancement Based on Transient Modification ...... Michael M. Goodwin and Carlos Avendano 827 In contrast to the conventional definition of audio enhancement as improving an objective measure of signal quality, this study treats enhancement as an artistic freedom used by either professionals or listeners. Two examples of spectral-based transient manipulation demonstrate this concept. In the first case, a transient characterization analysis is used to drive frequency-dependent modifications. In the second case, the modulation spectrum is manipulated by modifying the time trajectories of spectral envelopes. Such enhancements change the aural experience without introducing artifacts. Noise Power Modulation in Dithered and Undithered High-Order Sigma–Delta Modulators ...... Ivar Løkken, Anders Vinje, and Trond Sæther 841 Optimizing high-order sigma–delta modulators often focuses on quantizer distortion and idle tones while ignoring the consequences of noise power modulation. This study focuses on simulations of noise modulation in the baseband for various topologies with and without dither. The assumption that high-order dithering in sigma–delta modulators is equivalent to the corresponding dithering in linear pulse-code modulation proved to be erroneous. Noise power modulation must be simulated for each implementation when optimizing the loop filter and dithering strategy.

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 855 AESSC vice chair; audio file format; audio disk format; AES3 using coaxial cable; sample-accurate timing in AES47; audio applications of IEEE 1394; forensic audio; loudspeaker measurement

FEATURES 28th Conference Report, Piteå, Sweden...... 858 Next Generation of Audio Communications ...... 865 Education News...... 868 122nd Convention, Vienna, Call for Papers...... 893 31st Conference, London, Call for Papers ...... 894

DEPARTMENTS News of the Sections...... 869 Membership Information...... 882 Upcoming Meetings ...... 875 Advertiser Internet Directory...... 885 Sound Track ...... 876 In Memoriam ...... 891 Available Literature...... 878 Sections Contacts Directory ...... 896 New Products and Developments...... 880 AES Conventions and Conferences ...... 904 p906_TOC_Oct.qxd 10/11/06 12:45 PM Page 1

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AVOLUME 54E NUMBERS 10 2006 OCTOBER CONTENTS TUTORIALS Tutorial: Loudspeaker Nonlinearities—Causes, Parameters, Symptoms ...... Wolfgang Klippel 907 This comprehensive review and tutorial discussion about nonlinear distortion in loudspeakers offers a clear perspective: under the right conditions, measurements may manifest particular nonlinear electromechanical mechanisms. Because there are a large number of such mechanisms, signals must be carefully selected to excite particular nonlinearities. A catalog of observable manifestations provides a working recipe for diagnosing defects, which then makes possible design improvement. Three examples illustrate this approach. PAPERS Efficient Resonant Loudspeakers with Large Form-Factor Design Freedom ...... Ronald M. Aarts, Joris A. M. Nieuwendijk, and Okke Ouweltjes 940 It is not possible to combine high efficiency and wide frequency bandwidth in small cabinet loudspeakers. However, by changing assumptions and allowing nonlinear electronic processing, a small loudspeaker can operate in the high-efficiency spectral region. Compressing the 2.5-octave region from 20 to 120 Hz into a narrow frequency at the natural resonances of the loudspeaker provides a means for optimizing both size and efficiency. However, acoustic quality at low frequencies is compromised. An experimental prototype illustrates the approach. Vibrotactile Enhancement of Auditory-Induced Self-Motion and Spatial Presence ...... Aleksander Väljamäe, Pontus Larsson, Daniel Västfjäll, and Mendel Kleiner 954 Using cross-modal stimulation of multiple senses can enhance the illusion of motion in entertainment and virtual environments. Mechanically induced vibrations significantly improve the sense of self-motion and presence. Since vestibular excitation is not possible when not actually moving, auditory and tactile sensations can enhance an illusion of movement and presence in virtual environments. Examples of using three audio-tactile scenes illustrate the degree to which an illusion of movement is created. ENGINEERING REPORTS Virtual Air Guitar ...... Matti Karjalainen, Teemu Mäki-Patola, Aki Kanerva, and Antti Huovilainen 964 Playing a virtual guitar by tracking hand motions illustrates an approach to a natural user interface for synthesized music. Three different methods for sensing hand motion and position have been tried: data gloves in a virtual room, optical tracking of hand movement, and special control sticks that sense acceleration. Of these, optical tracking with a web camera offers the least expensive approach, since such devices are often part of a computer system. Demonstration systems at Heureka Science Center have allowed thousands of visitors to enjoy the feeling of being a rock star. Eventually, this approach may lead to the evolution of professional musical instruments. LETTERS TO THE EDITOR Comments on “Model Optimization of Distributed-Mode Loudspeaker Using Attached Masses” ...... Frank Fahy 981 Authors’ Reply...... Suzhen Zhang and Yong Shen 981 Comments on “Low-Frequency Optimization Using Multiple Subwoofers” ...... Earl R. Geddes 983 Authors’ Reply ...... Todd Welti and Alan Devantier 984 CORRECTIONS Corrections to “Noise Power Modulation in Dithered and Undithered High-Order Sigma–Delta Modulators” ...... Ivar Løkken, Anders Vinje, and Trond Sæther 985 STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 986 Acoustics and sound-source modeling; audio connectors; grounding and EMC FEATURES Binaural Technology for Mobile Applications...... 990 New Officers 2006/2007...... 996 Review of Society’s Sustaining Members ...... 1001 122nd Convention, Vienna, Call for Papers...... 1037 31st Conference, London, Call for Papers ...... 1038 32nd Conference, Hillerød, Call for Papers...... 1039 DEPARTMENTS Reviews of Acoustical Patents...... 987 Membership Information...... 1032 News of the Sections...... 1023 Advertiser Internet Directory...... 1035 Upcoming Meetings ...... 1026 In Memoriam ...... 1036 Sound Track ...... 1027 Sections Contacts Directory ...... 1040 New Products and Developments...... 1030 AES Conventions and Conferences ...... 1048 Available Literature...... 1031 p1050_TOC_Nov.qxd 11/7/06 12:42 PM Page 1

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AVOLUME 54E NUMBERS 11 2006 NOVEMBER

CONTENTS

PAPERS Multiple-Loudspeaker Playback of Stereo Signals ...... Christof Faller 1051 In order to avoid the legacy of the implied loudspeaker configuration for traditional stereo signals, they can be decomposed into virtual sources. Such spatial decomposition allows a resynthesis to match to a new loudspeaker configuration, especially with additional front loudspeakers. Uncorrelated signal components, corresponding to ambiance, drive the side loudspeakers. Subjective tests illustrate that listeners prefer the new system not only when outside of the sweet spot, but also at the sweet spot. Structural and Acoustic Analysis of Multiactuator Panels ...... Martin Kuster, Diemer de Vries, Daniel Beer, and Sandra Brix 1065 The requirement of a large number of loudspeakers for wavefield synthesis can be achieved using transducers composed of panels with multiple actuators. The proposed transducers are flat, lightweight sandwich panels driven by an array of exciters. Ideally, each exciter should generate a well-defined point source of radiation. Using a vibrometer, it was shown that the influence of neighboring exciters and panel edges are minimal. Large damping losses, which are critical for making multiple exciters independent, were found to be appropriate for this application. A single panel is a viable alternative for an array of conventional loudspeakers. Synthesis and Implementation of Virtual Bass System with a Phase-Vocoder Approach ...... Mingsian R. Bai and Wan-Chi Lin 1077 Small multimedia loudspeakers and handheld players cannot reproduce low frequencies without also creating nonlinear distortion that results when overdriving their limited dynamic range. However, the human auditory system can extrapolate missing low-frequency fundamentals from higher overtones, so-called residual pitch, thereby creating the impression of the missing bass. Using a phase vocoder, low-frequency components are used to create three overtones to simulate the loudness of the missing component. Subjective tests showed that this approach produced better timbral quality than the traditional approach of nonlinear processing of low frequencies to generate bass sensation.

ENGINEERING REPORTS Validation of ITU-T P.563 Single-Ended Objective Speech Quality Measurement ...... Antti Kurituu 1092 Assessing the audio quality of telecommunication networks using the P.563 standard, which does not require access to the original signal, offers the advantage of simplicity, efficiency, and objectivity. This study examines the relationship of the P.563 metric to the corresponding results obtained from subjective listening tests. Unfortunately, although showing the correct trends, P.563 metric presents results on a compressed scale compared to the subjective quality range, thereby greatly reducing its utility in evaluating narrow-band telephony applications presented in the paper. Refinements to P.563 are required when assessing speech quality.

STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 1099 AES53 sample-accurate timing; storage and handling of media; digital library and archive systems; audio metadata; microphone measurement; digital audio measurement; audio-file exchange

FEATURES Using Game-Audio Tools to Build Audio Research Applications...... Michael Kelly 1102 Preventing Hearing Loss ...... 1109 32nd Conference, Hillerød, Call for Papers...... 1127

DEPARTMENTS News of the Sections...... 1114 Advertiser Internet Directory...... 1123 Upcoming Meetings ...... 1117 AES Awards ...... 1125 Sound Track ...... 1118 AES Annual Report ...... 1126 Available Literature...... 1120 Sections Contacts Directory ...... 1128 New Products and Developments...... 1121 AES Conventions and Conferences ...... 1136 Membership Information...... 1122 p1138_TOC_Dec.qxd 12/18/06 3:43 PM Page 1

JOURNAL OF THE AUDIO ENGINEERING SOCIETY AUDIO/ACOUSTICS/APPLICATIONS AVOLUME 54E NUMBERS 12 2006 DECEMBER CONTENTS President’s Message...... Wieslaw Woszczyk 1139 PAPERS Equalization in an Extended Area Using Multichannel Inversion and Wave Field Synthesis ...... E. Corteel 1140 Because of the nonideal directivity of loudspeakers in wave field synthesis, the conventional approach of individually equalizing each loudspeaker does not produce an accurate soundfield over an extended area of the listening space. A new method for equalization considers the full array of loudspeakers as a complete multiple-input multiple-output (MIMO) system. In the proposed multichannel inversion scheme, compensation is achieved for a limited ensemble of elementary virtual sources. Results show that the approach reduces rendering artifacts and spectral coloration over an extended listening area. Filter Design Method for Loudspeaker Equalization Based on IIR Parametric Filters ...... Germán Ramos and José J. López 1162 Equalizing a loudspeaker using a cascade sequence of second-order sections (low-pass, high-pass, or peak filter) is a viable alternative to the more conventional approach of a single large FIR filter. In order to optimize the parameters of each filter section, a two-step algorithm begins by first searching for a good initial solution and then applying a heuristic method using subjective criteria. The solution is scalable, subjectively validated, and produces a computational cost reduction in comparison to the conventional approach for the same degree of performance. Perceptually Biased Linear Prediction...... Arijit Biswas and Albertus C. den Brinker 1179 In contrast to the standard linear prediction-based perceptual audio coding that uses a separate psychoacoustic model, the authors propose Laguerre-based linear prediction employing a perceptually biased solution. This greatly reduces the computational complexity because a separate psychoacoustic model is no longer required. Subjective listening tests show that the resulting audio quality is similar to that of the traditional approach. ENGINEERING REPORTS Application and Verification of the Objective Quality Assessment Method According to ITU Recommendation Series ITU-T P.862 ...... Antti Kurittu, Juha Salmela, Olli Kirla, Ari Lakaniemi, Ville-Veikko Mattila, and Nick Zacharov 1189 In recent years a number of speech quality prediction algorithms have been developed for evaluating telecommunications systems. The family of ITU-T recommendation P.862 is frequently used to create a mean opinion score of quality. Although these algorithms have been evaluated under common testing conditions for narrow- and wide-band speech signals, care must be used when these standards are applied to channels more specialized degradations, such as spectral aberrations, time scaling, and environmental noise. This study has discovered certain cases of suboptimal accuracy. As with the use of all quality-metric tools, the user must heed their limitations and scope of applicability in order to avoid erroneous conclusions. LETTERS TO THE EDITOR Comments on “Smart Digital Loudspeaker Arrays”...... D. B. (Don) Keele, Jr. 1203 STANDARDS AND INFORMATION DOCUMENTS AES Standards Committee News...... 1215 Personal computer audio quality measurements; storage environment for multiple media; polarity of audio signals; connectors for loudspeaker patch panels; analog recording; transfer technologies; storage and handling of media; digital library and archive systems; microphone measurement and characterization FEATURES 121st Convention Report, San Francisco...... 1218 Exhibitors...... 1235 Program ...... 1241 30th Conference Preview, Saariselkä, Finland...... 1294 Calendar ...... 1296 Program...... 1297 Registration Form...... 1304 Forging Ahead with Spatial Audio Coding...... 1305 Education News...... 1314 Call for Nominations for the Board of Governors...... 1318 Call for Awards Nominations...... 1319 13th Regional Convention, Tokyo, Call for Papers ...... 1324 Bylaws: Audio Engineering Society, Inc...... 1325 Index to Volume 54 ...... 1329 DEPARTMENTS News of the Sections...... 1309 Membership Information...... 1320 Upcoming Meetings ...... 1313 Advertiser Internet Directory...... 1322 Sound Track ...... 1315 Sections Contacts Directory ...... 1344 New Products and Developments...... 1317 AES Conventions and Conferences ...... 1352