AAEESS 112244tthh CCOONNVVEENNTTIIOONN PPRROOGGRRAAMM May 17 – 20, 2008 RAI International Exhibition & Congress Centre, Amsterdam The AES has launched a new opportunity to recognize 1University of Salford, Salford, Greater student members who author technical papers. The Stu- Manchester, UK dent Paper Award Competition is based on the preprint 2ICW, Ltd., Wrexham, Wales, UK manuscripts accepted for the AES convention. Forty-two student-authored papers were nominated. This paper gives an account of work carried out The excellent quality of the submissions has made the to assess the effects of metallized film selection process both challenging and exhilarating. polypropylene crossover capacitors on key sonic The award-winning student paper will be honored dur- attributes of reproduced sound. The capacitors ing the convention, and the student-authored manuscript under investigation were found to be mechani- will be published in a timely manner in the Journal of the cally resonant within the audio frequency band, Audio Engineering Society. and results obtained from subjective listening Nominees for the Student Paper Award were required tests have shown this to have a measurable to meet the following qualifications: effect on audio delivery. The listening test methodology employed in this study evolved (a) The paper was accepted for presentation at the from initial ABX type tests with set program AES 124th Convention. material to the final A/B tests where trained test (b) The first author was a student when the work was subjects used program material that they were conducted and the manuscript prepared. familiar with. The main findings were that (c) The student author’s affiliation listed in the manu- capacitors used in crossover circuitry can exhibit script is an accredited educational institution. mechanical resonance, and that maximizing the (d) The student will deliver the lecture or poster pre- listener’s control over the listening situation and sentation at the Convention. minimizing stress to the listener were necessary ***** to obtain meaningful subjective test results. Convention Paper 7314 The winner of the 124th AES Convention Student Paper Award is: Modeling Frequency-Dependent Boundaries as Digital Impedance Filters in FDTD 09:30 and K-DWM Room Acoustic Simulations —Konrad Kowalczyk (Presenting Author) P1-2 Perceptual Study and Auditory Analysis on and Maarten van Walstijn, Digital Crossover Filters—Henri Korhola, Matti Convention Paper 7430 Karjalainen, Helsinki University of Technology, Espoo, Finland To be presented on Monday, May 19 in Session P18 Digital crossover filters offer interesting possibili- —Room and Architectural Acoustics and Sound ties for sound reproduction, but there does not Reinforcement exist many publications on how they behave per- ceptually. In this paper phase and magnitude * * * ** errors in digital implementations of linear phase FIR as well as Linkwitz-Riley crossover filters are Friday, May 16 13:30 Room H studied perceptually and by auditory analysis. In Standards Committee Meeting on SC-02-02 Digital a headphone simulation listening experiment we Input/Output Interfacing explored the just noticeable level of degradation due to crossover filter artifacts. In a real loud- Session P1 Saturday, May 17 speaker experiment we explored rough guidelines 09:00 – 12:00 Room C-D for “safe” filter orders of linear-phase FIR crossover filters, which would not produce audible LOUDSPEAKERS, PART 1 errors. Possibilities to predict the perceived errors were then explored using auditory analysis, Chair: Stanley Lipshitz, University of Waterloo, including also third-octave magnitude spectrum Waterloo, Ontario, Canada and group delay as simple auditory correlates. Linear-phase FIR crossovers were found to pro- 09:00 duce different kinds of phase errors than Linkwitz- Riley crossovers. The auditory analysis can quali- P1-1 Audio Capacitors. Myth or Reality?—Philip tatively explain the perceptibility degradation. Duncan,1 Paul Dodds,2 Nigel Williams2 Convention Paper 7315 ¯ Audio Engineering Society 124th Convention Program, 2008 Spring 1 Technical Program 10:00 11:30 P1-3 The Air Spring Effect of Flat Panel P1-6 Audibility of Phase Response Differences in Loudspeakers—Daniel Beer,1 Michaela a Stereo Playback System. Part I: Headphone Schuster,2 Michael Jahr,2 Alexander Reich1 Reproduction of Wide-Band Stimuli—Geoff 1Fraunhofer Institute for Digital Media Martin, Sylvain Choisel, Bang & Olufsen A/S, Technology, Ilmenau, Germany Struer, Denmark 2Technical University Ilmenau, Ilmenau, Germany The audibility of phase distortion in sound repro- Flat panel loudspeakers are characterized by duction systems has been the subject of many their low manufactured depth. Compared with studies. However, it remains a topic of contro- conventional loudspeakers the space saving versy, in particular in the field of loudspeaker or integration in existing surroundings is an advan- headphone equalization. Most studies lead to tage. From the acoustics point of view disadvan- the conclusion that, although phase distortion tages come along with the low manufactured may be audible for specific stimuli, in realistic lis- depth that influence the reproduction in the lower tening situations in a room, they will go largely and middle frequency range. Based on mea- unnoticed. These studies, however, have surements and FEM-simulations the reasons for focused on monophonic phase distortion; a this behavior were analyzed. Supplementary severe limitation, since ignoring phase response methods for solving this problem have been con- in equalization can result in different phase dis- sidered that are derived from conventional loud- tortion in different channels. It is the purpose of speaker technologies. the present study to investigate the audibility of Convention Paper 7316 stereophonic phase mismatch in the specific case of headphone reproduction. In addition, the 10:30 implications on microphone design and produc- tion are discussed. P1-4 The Inertial Air Load of a Loudspeaker Convention Paper 7319 Diaphragm—John Vanderkooy, University of Waterloo, Waterloo, Ontario, Canada, and B&W Group Ltd., Steyning, West Sussex, UK Workshop 1 Saturday, May 17 A typical bass loudspeaker driver has an inertial 09:00 – 10:30 Room L air load, which is about 30% of its actual cone mass. This air mass is often poorly understood, PRODUCTION OF SURROUND SOUND WITH HDTV but it is significant in defining the resonance fre- quency; and the purpose of this paper is to Chairs: Kimio Hamasaki, NHK Science and understand the concept, clarify important as- Technical Research Laboratories, pects, and present corroborative measurements. Tokyo, Japan The immediate surroundings of the diaphragm Christian Hugonnet, Audio Engineering determine the low-frequency air load, and mea- Consultant, Paris, France surements on a test driver with different mount- ings arrangements are made and assessed, including measurements in vacuum. A loud- Panelists: Florian Camerer, ORF - Austrian TV speaker box presents its own complications. Toru Kamekawa, Tokyo University of Fine Simulations are used to show how the air load Arts and Music, Tokyo, Japan depends on baffle size. In general, the air load may not be accurately represented by the usual HDTV is currently broadcasted in many countries over approximations that apply to a piston in an infi- the world. 5.1 channel surround sound has made great nite baffle or to a freely oscillating disk, but they progress in digital broadcasting. Many workshops have do give a rough estimate. discussed the 5.1 channel surround sound at previous Convention Paper 7317 AES conventions; however, 5.1 channel sound produc- tion and broadcasting accompanying HDTV has not 11:00 been discussed as often at previous conventions. This P1-5 Horn Loudspeaker Nonlinearty Comparison workshop will focus on the 5.1 surround sound produc- and Linearization Using Volterra Series— tion and broadcasting for HDTV and discuss various Delphine Bard, University of Lund, Lund, Sweden issues such as sound recording, sound design, postpro- duction, and aesthetic approaches in terms of 5.1 chan- The characterization of a weakly nonlinear elec- nel sound with large and high-resolution pictures. troacoustic device with usual methods of measurement (THD, intermodulation) does not Tutorial 1 Saturday, May 17 illustrate the nonlinearities themselves, but only 09:00 – 12:00 Room N101 some of their effects. Device linearization can be achieved by applying the inverse nonlinearity PERCEPTUAL AUDIO EVALUATION upstream of the device, under the condition that the nonlinearity law is known in detail. This paper presents nonlinearities behavior compari- Presenters: Søren Bech son of horn loudspeakers of different frequency Nick Zacharov ranges using an experimental method of weak The aim of this tutorial is to provide an overview of per- nonlinearity characterization and compensation, ceptual evaluation of audio through listening tests, based based on a representation of the nonlinearity by on good practices in the audio and affiliated industries. Volterra series using multitone excitations. The tutorial is geared to anyone interested in the evalua- Convention Paper 7318 tion of audio quality and will provide a highly condensed 2 Audio Engineering Society 124th Convention Program, 2008 Spring overview of all aspects of performing listening tests in a used are usually well managed corporate net- robust manner. works with good Quality of Service (QoS) and usu- Topics will include: ally