DOCSLIB.ORG

The Pennsylvania State University

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Pennsylvania State University The Pennsylvania State University The Graduate School EFFECTS OF PERTURBATIONS ON THE REVERBERANT SOUND FIELD OF A ROOM A Thesis in Acoustics by Sumeet Sanjay Gawali © 2020 Sumeet Sanjay Gawali Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science May 2020 ii The thesis of Sumeet Gawali was reviewed and approved by the following: Stephen Thompson Research Professor Thesis Advisor Daniel Russell Teaching Professor of Acoustics and Distance Education Coordinator Robert Smith Assistant Research Professor Victor Sparrow Director of Graduate Program in Acoustics and United Technologies Corporation Professor of Acoustics iii ABSTRACT The reverberant sound field in a room, with all surfaces of the room being stationary, depends on the objects present in the room and their reflective or absorptive features and partly expressed in the reverberation time of the room. However, if perturbations are introduced in the sound field, either by moving objects in a room or by introducing new moving objects in the room with reflective or absorptive characteristics, the reverberant sound field undergoes modifications as the reflections change and in turn change how sound waves in a room interfere with each other at different locations in the room. These changes can be observed by making a comparison measurement between the frequency response of the room when it is stationary and when it is being perturbed. In this research effort, the impact on the time averaged sound field of a person moving through four candidate rooms was examined to assess the impact of this type of practical and easily achieved level of perturbation on a room. Hence, a comparison measurement was conducted in various rooms on the University Park campus of the Penn State University to analyze and study the effects of this type of perturbations on the sound field of a room. In the four types of rooms examined in this study, it was found that a person walking around did not produce what would be a significant improvement on averaging sound pressure level uniformity over the distribution of measured points in the rooms. iv TABLE OF CONTENTS LIST OF FIGURES ............................................................................................................ vi LIST OF TABLES .............................................................................................................. x ACKNOWLEDGEMENTS ................................................................................................ xi Chapter 1 Introduction ....................................................................................................... 1 Chapter 2 Reverberant and Diffuse field ............................................................................. 6 Reverberant field ......................................................................................................... 7 Diffuse Field ............................................................................................................... 9 Schroeder frequency .................................................................................................... 10 Chapter 3 Overview of Measurements ................................................................................ 15 General Setup .............................................................................................................. 15 Equipment ................................................................................................................... 16 Audio Signal ........................................................................................................ 17 Sound Source ....................................................................................................... 17 Microphones ........................................................................................................ 19 Audio Interface .................................................................................................... 19 Storage and processing ......................................................................................... 20 Chapter 4 Measurements and Data Analysis ....................................................................... 22 Microphone sensitivity measurements ......................................................................... 23 Reverberation time (RT60) measurement..................................................................... 24 Background noise measurement................................................................................... 27 Comparison measurement............................................................................................ 28 Stationary measurement ....................................................................................... 28 Perturbed measurement ........................................................................................ 28 Data Analysis .............................................................................................................. 29 Reverberation time (RT60) measurement ............................................................. 29 Comparison measurements................................................................................... 31 Chapter 5 Conference Room – Data Analysis ..................................................................... 33 General construction and features ................................................................................ 33 Reverberation time (RT60) measurement..................................................................... 34 Preliminary calculations .............................................................................................. 36 Background noise measurement................................................................................... 37 Comparison measurement............................................................................................ 38 Chapter 6 Room #22 (Hammond Building) – Data Analysis ............................................... 44 v General construction and features ................................................................................ 44 Reverberation time (RT60) measurement..................................................................... 45 Preliminary calculations .............................................................................................. 47 Background noise measurement................................................................................... 48 Comparison measurement............................................................................................ 50 Chapter 7 Reverberation chamber – Data analysis .............................................................. 56 General construction and features ................................................................................ 56 Reverberation time (RT60) measurement..................................................................... 57 Preliminary calculations .............................................................................................. 58 Background noise measurement................................................................................... 59 Comparison measurement............................................................................................ 61 Chapter 8 Ensemble A 132 (Music Building - II) – Data analysis ....................................... 68 General construction and features ................................................................................ 68 Reverberation time (RT60) measurement..................................................................... 69 Preliminary calculations .............................................................................................. 71 Background noise measurement................................................................................... 72 Comparison measurement............................................................................................ 73 Chapter 9 Conclusion ......................................................................................................... 80 Appendix Schroeder frequency ......................................................................................... 83 vi LIST OF FIGURES Figure 1-1: Experimental study conducted by Arthur Benade in his Laboratory space showing the effect of a person walking around in a room ............................................. 12 Figure 1-2 The four rooms measured for this research study ................................................ 5 Figure 2-1: Newell’s graph representing the concept of critical distance in a room. .............. 8 Figure 2-2: General categories of Room Modes. .................................................................. 12 Figure 2-3: Frequency response of a rectangular room of volume 180 cu. m. showing the modal density of the room ........................................................................................... 112 Figure 3-1: General signal flow chain. ................................................................................. 16 Figure 3-2: JBL Flip 4. ........................................................................................................ 18 Figure 3-3: Dayton Audio Emm6 Electret microphone. ....................................................... 19 Figure 3-4: Zoom F8n Multitrack field recorder. ................................................................. 20 Figure 4-1: B&K Type 4231 Sound Calibrator. ..................................................................
Load more

Recommended publications
  • Room Acoustics and Reverberation
    21m.380 · Music and Technology Recording Techniques & Audio Production Room acoustics & reverberation Session 18 · Wednesday, November 9, 2016 1 Pa1 presentations • • Flo: Randy Newman – A Few Words in Defense of Our Country (2006) 2 Announcement: Schlepping reminder • Please remember if you are signed up for pre- or post-class schlepping for either recording session on Mon, 11/14, Wed, 11/16. • Pre-class schlepping: Meet at , 10 minutes before class 3 Review 3.1 Recording session 1 3.2 Ed3 assignment • How to limit to −3 dB with ReaComp plugin – Large ratio – Small rms size – Short attack and release times • Review of setting up a gate 4 Audible effects of reflections & delays 4.1 Flutter echoes & resonances • Unpleasant flutter echoes tend to occur between hard, parallel walls • Real-world examples: Killian Hall – Front right stage area as seen from audience (floor & ceiling) – Center of room with folded-in wall panels (left & right wall) • Demo in Pd: Perceptual effect of delays – ≳ 30 ms: Audible as echoes – ≲ 30 ms: Audible as pitched resonance – why? 1 of 10 21m.380 · Room acoustics & reverberation · Wed, 11/9/2016 4.2 Comb filters +6 Figure 2. Comb filter frequency re- sponse (note linear 푥 axis −20 (dB) −40 gain −60 −80 푛 푛+1 푛+2 Δ푡 Δ푡 Δ푡 … Frequency 푓 (Hz) input • Result of mixing a sound with a copy of itself delayed by Δ푡: – Δ푡 = 푇, 2푇, 3푇, ⋯ = 푛 Constructive interference if 푓 푇 3푇 5푇 – Destructive interference if Δ푡 = 2 , 2 , 2 ,… • Sound example: pink noise, moving mic, reflective surface Delay Δ푡 • Can be enjoyed outdoors across mit campus; just combine: + – Broadband hvac noise – Reflections from nearby building walls – Moving observer output • Other ubiquituous examples: Figure 1.
    [Show full text]
  • Loudspeakers and Rooms for Sound Reproduction—A Scientific Review*
    PAPERS Loudspeakers and Rooms for Sound Reproduction—A Scientific Review* FLOYD E. TOOLE ([email protected]) Harman International Industries, Inc., Northridge, CA 91329, USA The physical measures by which acousticians evaluate the performance of rooms have evolved in large performance spaces—concert halls. They rely on assumptions that become progressively less valid as spaces get smaller and more acoustically absorptive. In listening rooms the loudspeakers and the rooms interact differently below and above a transition region around 300 Hz, similar to the Schroeder frequency in large rooms. Above this transition we need to understand our reactions to reflected sounds; below it the modal behavior of the space is the dominant factor. A review of the scientific literature reveals that natural reflections in small rooms are at levels where they are perceptible, and their subjectively judged effects range from neutral to positive. At low frequencies the long-standing problem of room reso- nances can be alleviated substantially through the use of multiple subwoofers, thereby pro- viding similarly good bass to several listeners in a room. A provocative observation has to do with human adaptation to the complexities of reflective rooms, and the extent to which it allows us to localize sounds correctly in direction and distance, and to hear much of the true timbral nature of sound sources. In the case of loudspeakers, an analysis of comprehensive anechoic data is found to be sufficient to provide a good prediction of sound quality, above the low-bass frequencies, as subjectively judged in a normal room. Although the interactions of loudspeakers and listeners in small rooms are becoming clearer, there are still gaps in our understanding.
    [Show full text]
  • Measurements for Loudspeaker Modeling Files
    Excelsior Audio Design & Services 2130 Shadwell Court 704.675.5435 4471 Posterity Court Gastonia, NC 28056 www.excelsior-audio.com Gastonia, NC 28056 Audio & Acoustical Consulting, Design, and Measurement 22 March 2017 Charlie Hughes Measurements for Loudspeaker Modeling Files Loudspeaker modeling files are most often used with acoustical modeling programs such as EASE, Focus, CATT-Acoustic, and others to help determine how well the loudspeakers cover the audience areas and how much “spill” there is on the room’s surfaces. Some of these programs also allow for the investigation of additional metrics like reverberation time, clarity, speech transmission index (STI), and more. For many of these items it is important to have accurate data about the characteristics of the loudspeakers that are used in the models. Errors in the data used for these modeling programs will often lead to errors in the results the programs generate. In this article we will details some of the requirements to help assure good measurement data for use with loudspeaker modeling. It is also possible to use some of these loudspeaker modeling files to help optimize the design of crossover filters for the loudspeaker system. Since these modeling files have both on-axis and off-axis data the effects of the crossover and equalization filters used for each pass band can be seen in the overall directivity response of the loudspeaker system. We will also show an example of this in a follow-up article. While it is sometimes possible to measure a multi-transducer loudspeaker system as a single radiating, full-range device, these measurements may be limited in their use.
    [Show full text]
  • Microphone Techniques for RECORDING
    A Shure Educational Publication MICROPHONE TECHNIQUES RECORDING Microphone Techniques for Table of Contents RECORDING Introduction: Selection and Placement of Microphones ............. 4 Section One .................................................................................. 5 Microphone Techniques ........................................................ 5 Vocal Microphone Techniques ............................................... 5 Spoken Word/“Podcasting” ................................................... 7 Acoustic String and Fretted Instruments ................................ 8 Woodwinds .......................................................................... 13 Brass ................................................................................... 14 Amplified Instruments .......................................................... 15 Drums and Percussion ........................................................ 18 Stereo .................................................................................. 21 Introduction: Fundamentals of Microphones, Instruments, and Acoustics ....................................................... 23 Section Two ................................................................................ 24 Microphone Characteristics ................................................. 24 Instrument Characteristics ................................................... 27 Acoustic Characteristics ....................................................... 28 Shure Microphone Selection Guide ....................................
    [Show full text]
  • Microphone Techniques
    A Shure Educational Publication MICROPHONE TECHNIQUES RECORDING Microphone Techniques for Table of Contents RECORDING Introduction: Selection and Placement of Microphones ............. 4 Section One .................................................................................. 5 Microphone Techniques ........................................................ 5 Vocal Microphone Techniques ............................................... 5 Spoken Word/“Podcasting” ................................................... 7 Acoustic String and Fretted Instruments ................................ 8 Woodwinds .......................................................................... 13 Brass ................................................................................... 14 Amplified Instruments .......................................................... 15 Drums and Percussion ........................................................ 18 Stereo .................................................................................. 21 Introduction: Fundamentals of Microphones, Instruments, and Acoustics ....................................................... 23 Section Two ................................................................................ 24 Microphone Characteristics ................................................. 24 Instrument Characteristics ................................................... 27 Acoustic Characteristics ....................................................... 28 Shure Microphone Selection Guide ....................................
    [Show full text]
  • Remix Theory
    ~ SpringerWienNewYork Eduardo Navas .000• 00.00 .000. 00000 .000.••••• •••••• 0000 ••0 •• 00.00 0.0.0 00000 .0.0 • 00.00 00.00 00.00 .00.0••••• •••••• 0000 .000• 00.00 0.0.0 00000 • 000. ••••• .000• 00.00 .000. 00000 • 000• .000• •••••00.00 .000. •••••• 0000 •••••• 000• .000•••••• 0.0.0 00.00 • 000• 00.00 00.00 .000.••••• •••••• 0000 .000• .00.0••••• 00.00 00.00 • 000. ••••• ••••• .000• 00.00 THE AESTHETICS OF SAMPLING SpringerWienNewYork Eduardo Navas, Ph.D. Post-Doctoral Research Fellow Information Science and Media Studies University of Bergen, Norway With financial support of The Department of Information Science and Me- dia Studies at The University of Bergen, Norway. This work is subject to copyright. All rights are reserved, whether the whole or part of the material is con- cerned, specifically those of translation, reprinting, re-use of illustrations, broadcasting, reproduction by photocopying machines or similar means, and storage in data banks. Product Liability: The publisher can give no guarantee for all the informa- tion contained in this book. The use of registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific state- ment, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. © 2012 Springer-Verlag/Wien SpringerWienNewYork is part of Springer Science+Business Media springer.at Cover Image: Eduardo Navas Cover Design: Ludmil Trenkov Printing: Strauss GmbH, D-69509 Mörlenbach Printed on acid-free and chlorine-free bleached
    [Show full text]
  • The Routledge Companion to Remix Studies
    THE ROUTLEDGE COMPANION TO REMIX STUDIES The Routledge Companion to Remix Studies comprises contemporary texts by key authors and artists who are active in the emerging field of remix studies. As an organic interna- tional movement, remix culture originated in the popular music culture of the 1970s, and has since grown into a rich cultural activity encompassing numerous forms of media. The act of recombining pre-existing material brings up pressing questions of authen- ticity, reception, authorship, copyright, and the techno-politics of media activism. This book approaches remix studies from various angles, including sections on history, aes- thetics, ethics, politics, and practice, and presents theoretical chapters alongside case studies of remix projects. The Routledge Companion to Remix Studies is a valuable resource for both researchers and remix practitioners, as well as a teaching tool for instructors using remix practices in the classroom. Eduardo Navas is the author of Remix Theory: The Aesthetics of Sampling (Springer, 2012). He researches and teaches principles of cultural analytics and digital humanities in the School of Visual Arts at The Pennsylvania State University, PA. Navas is a 2010–12 Post- Doctoral Fellow in the Department of Information Science and Media Studies at the University of Bergen, Norway, and received his PhD from the Program of Art and Media History, Theory, and Criticism at the University of California in San Diego. Owen Gallagher received his PhD in Visual Culture from the National College of Art and Design (NCAD) in Dublin. He is the founder of TotalRecut.com, an online com- munity archive of remix videos, and a co-founder of the Remix Theory & Praxis seminar group.
    [Show full text]
  • Countercultures and Popular Music
    COUNTERCULTURES AND POPULAR MUSIC A translated and edited edition of a special issue of Volume! The French Journal of Popular Music Studies (Éditions Mélanie Seteun). Additional articles published in both ‘countercultures’ issues of Volume! can be found at: http://www.cairn.info/revue-volume.htm and http://volume.revues.org. Volume! is the only French peer-reviewed popular music studies journal. Created in 2002 by Marie-Pierre Bonniol, Samuel Étienne and Gérôme Guibert, it is published independently by the Éditions Mélanie Seteun, a publishing association specialising since 1998 in the cultural sociology of popular music. Biannual special issues deal with various topics in popular music studies, in a multidisciplinary perspective. It is also included on the online international academic portals Cairn.info and Revues.org. Volume! is classified by the French AERES and abstracted/indexed on the International Index to Music Periodicals, the Répertoire International de Littérature Musicale and the Music Index. This page has been left blank intentionally Countercultures and Popular Music Edited by SHEILA WHITELEY University of Salford, UK JEDEDIAH SKLOWER Université Sorbonne Nouvelle, Paris 3, France © Sheila Whiteley and Jedediah Sklower and the contributors 2014 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise without the prior permission of the publisher. Sheila Whiteley and Jedediah Sklower have asserted their rights under the Copyright, Designs and Patents Act, 1988, to be identified as the editors of this work. Published by Ashgate Publishing Limited Ashgate Publishing Company Wey Court East 110 Cherry Street Union Road Suite 3-1 Farnham Burlington, VT 05401-3818 Surrey, GU9 7PT USA England www.ashgate.com British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library.
    [Show full text]
  • Room Acoustics and Sound Reinforcement Systems
    Room Acoustics and Sound Reinforcement Systems Tadeusz Fidecki Contents Introduction ................................................................................................................................. 3 1. Wave theory approach ................................................................................................... 3 1.1 Eigenfrequencies and eigenmodes .......................................................................... 3 1.2 Modal density ............................................................................................................ 8 1.3 Loss factor and reverberation time ........................................................................... 8 1.4 Conclusion ................................................................................................................ 11 2. Statistical method ........................................................................................................... 12 2.1 The room response to the sound radiation ............................................................... 12 2.2 Reverberation in enclosures ..................................................................................... 13 2.3 Growth of energy in enclosure .................................................................................. 13 2.4 Decay of energy in enclosure ................................................................................... 14 2.5 Reverberation time ..................................................................................................
    [Show full text]
  • Speech Intelligibility - a JBL Professional Technical Note
    Technical Notes Volume 1, Number 26 Speech Intelligibility - A JBL Professional Technical Note 1. Introduction: The information presented in this broaa overview of sound reinforcement has been The purpose of a sound system is to trans• assembled from many sources. Through an mit information. In the case of public address, understanding of these essential principles, paging, voice alarm and speech reinforcement users will be better able to design, install and systems the object is to transmit intelligible troubleshoot sound systems for speech speech to listeners and intended message recipients. This aspect is far more important 2. Clarity and Audibility: than sound quality per se, since there is no point in designing a system if it can not be A common mistake often made when dis• understood or is incapable of 'getting the mes• cussing intelligibility is to confuse audibility sage across.' Although sound quality and with clarity. Just because a sound is audible speech intelligibility are inextricably linked, does not mean it will be intelligible. Audibility they are not the same. It is possible to have a relates to hearing sound, either from a physio• poor sounding system that is highly intelligible logical point of view or in terms of signal-to- (e. g., a frequency limited re-entrant horn with noise ratio. Clarity describes the ability to uneven response) and a high quality loud• detect the structure of a sound and, in the speaker that is virtually unintelligible (an case of speech, to hear consonants and vow• expensive hi-fi system in the center of an air• els and to identify words correctly craft hangar).
    [Show full text]
  • Equalization in Sound Reinforcement: Psychoacoustics, Methods, and Issues
    Canadian Acoustics / Acoustique Canadienne 24(1) 13-22 (1996) Review article / Article de revue EQUALIZATION IN SOUND REINFORCEMENT: PSYCHOACOUSTICS, METHODS, AND ISSUES Russell Ovans Jason Sound Industries, 1709 Welch St., N. Vancouver, BC V7P 3G9 and School of Computing Science, Simon Fraser University, Burnaby, BC V5A 1S6 [email protected] SUMMARY The practise of electroacoustic sound system equalization demands an understanding of psychoacoustics, room acoustics measurement, and subjective room acoustics. In this paper we undertake a review and syn­ thesis of the literature pertaining to the relevant psychoacoustic and room acoustic phenomena, and relate it to a number of issues regarding the current methods of large venue sound system equalization. SOMMAIRE L’utilisation de systèmes équalisateurs de son électroaccoustique exige la compréhension de la psy- cho-accoustique, des mesures de l’accoustique de salle et de l’accoustique subjective de salle. Nous présen­ tons dans cet articles une étude de synthèse de la litérature relative aux phénomènes de la psycho-accoustique et de l’accoustique de salle et relions cet étude à de nombreux problèmes qui se rappor­ tent aux méthodes courantes pour les systèmes équalisateurs de son pour grande salle. 1. INTRODUCTION preference. In this respect, equalization is closely related to the field of subjective room acoustics. Large venue sound reproduction systems consist of a net­ work of signal processing equipment through which an orig­ In this paper we first consider the relevant psychoacoustic inal source signal is routed on its journey to multiple (Section 2) and room acoustic phenomena (Section 3) before speakers at various locations within a room.
    [Show full text]
  • Effects of Interpersonal Familiarity on the Auditory Distance Perception of Level-Equalized Reverberant Speech
    Acta Acustica 2020, 4,26 Ó Ö. Demirkaplan & H. Hacıhabiboğlu, Published by EDP Sciences, 2020 https://doi.org/10.1051/aacus/2020025 Available online at: https://acta-acustica.edpsciences.org SCIENTIFIC ARTICLE Effects of interpersonal familiarity on the auditory distance perception of level-equalized reverberant speech Özgen Demirkaplan and Hüseyin Hacıhabiboğlu* Middle East Technical University (METU), Graduate School of Informatics, 06800 Çankaya, Ankara, Turkey Received 3 June 2020, Accepted 2 November 2020 Abstract – Familiarity with sound sources is known to have a modulatory effect on auditory distance percep- tion. However, the level of familiarity that can affect distance perception is not clearly understood. A subjective experiment that aims to investigate the effects of interpersonal familiarity on auditory distance perception with level-equalized stimuli is reported. The experiment involves a binaural listening task where different source distances between 0.5 and 16 m were emulated by convolving dry speech signals with measured binaural room impulse responses. The experimental paradigm involved level-equalized stimuli comprising speech signals recorded from different-gender couples who have self-reported to have known each other for more than a year with daily interaction. Each subject judged the distances of a total of 15 different speech stimuli from their part- ner as well as spectrally most similar and most dissimilar strangers, for six different emulated distances. The main finding is that a similar but unfamiliar speaker
    [Show full text]