8. Acoustics of Rooms and Enclosures
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Basics of Acoustics Contents
BASICS OF ACOUSTICS CONTENTS 1. preface 03 2. room acoustics versus building acoustics 04 3. fundamentals of acoustics 05 3.1 Sound 05 3.2 Sound pressure 06 3.3 Sound pressure level and decibel scale 06 3.4 Sound pressure of several sources 07 3.5 Frequency 08 3.6 Frequency ranges relevant for room planning 09 3.7 Wavelengths of sound 09 3.8 Level values 10 4. room acoustic parameters 11 4.1 Reverberation time 11 4.2 Sound absorption 14 4.3 Sound absorption coefficient and reverberation time 16 4.4 Rating of sound absorption 16 5. index 18 2 1. PREFACE Noise or unwanted sounds is perceived as disturbing and annoying in many fields of life. This can be observed in private as well as in working environments. Several studies about room acoustic conditions and annoyance through noise show the relevance of good room acoustic conditions. Decreasing success in school class rooms or affecting efficiency at work is often related to inadequate room acoustic conditions. Research results from class room acoustics have been one of the reasons to revise German standard DIN 18041 on “Acoustic quality of small and medium-sized room” from 1968 and decrease suggested reverberation time values in class rooms with the new 2004 version of the standard. Furthermore the standard gave a detailed range for the frequency dependence of reverberation time and also extended the range of rooms to be considered in room acoustic design of a building. The acoustic quality of a room, better its acoustic adequacy for each usage, is determined by the sum of all equipment and materials in the rooms. -
White Paper: Acoustics Primer for Music Spaces
WHITE PAPER: ACOUSTICS PRIMER FOR MUSIC SPACES ACOUSTICS PRIMER Music is learned by listening. To be effective, rehearsal rooms, practice rooms and performance areas must provide an environment designed to support musical sound. It’s no surprise then that the most common questions we hear and the most frustrating problems we see have to do with acoustics. That’s why we’ve put this Acoustics Primer together. In simple terms we explain the fundamental acoustical concepts that affect music areas. Our hope is that music educators, musicians, school administrators and even architects and planners can use this information to better understand what they are, and are not, hearing in their music spaces. And, by better understanding the many variables that impact acoustical environ- ments, we believe we can help you with accurate diagnosis and ultimately, better solutions. For our purposes here, it is not our intention to provide an exhaustive, technical resource on the physics of sound and acoustical construction methods — that has already been done and many of the best works are listed in our bibliography and recommended readings on page 10. Rather, we want to help you establish a base-line knowledge of acoustical concepts that affect music education and performance spaces. This publication contains information reviewed by Professor M. David Egan. Egan is a consultant in acoustics and Professor Emeritus at the College of Architecture, Clemson University. He has been principal consultant of Egan Acoustics in Anderson, South Carolina for more than 35 years. A graduate of Lafayette College (B.S.) and MIT (M.S.), Professor Eagan also has taught at Tulane University, Georgia Institute of Technology, University of North Carolina at Charlotte, and Washington University. -
Physics of Music PHY103 Lab Manual
Physics of Music PHY103 Lab Manual Lab #6 – Room Acoustics EQUIPMENT • Tape measures • Noise making devices (pieces of wood for clappers). • Microphones, stands, preamps connected to computers. • Extra XLR microphone cables so the microphones can reach the padded closet and hallway. • Key to the infamous padded closet INTRODUCTION One important application of the study of sound is in the area of acoustics. The acoustic properties of a room are important for rooms such as lecture halls, auditoriums, libraries and theatres. In this lab we will record and measure the properties of impulsive sounds in different rooms. There are three rooms we can easily study near the lab: the lab itself, the “anechoic” chamber (i.e. padded closet across the hall, B+L417C, that isn’t anechoic) and the hallway (that has noticeable echoes). Anechoic means no echoes. An anechoic chamber is a room built specifically with walls that absorb sound. Such a room should be considerably quieter than a normal room. Step into the padded closet and snap your fingers and speak a few words. The sound should be muffled. For those of us living in Rochester this will not be a new sensation as freshly fallen snow absorbs sound well. If you close your eyes you could almost imagine that you are outside in the snow (except for the warmth, and bizarre smell in there). The reverberant sound in an auditorium dies away with time as the sound energy is absorbed by multiple interactions with the surfaces of the room. In a more reflective room, it will take longer for the sound to die away and the room is said to be 'live'. -
Acoustic Textiles - the Case of Wall Panels for Home Environment
Acoustic Textiles - The case of wall panels for home environment Bachelor Thesis Work Bachelor of Science in Engineering in Textile Technology Spring 2013 The Swedish school of Textiles, Borås, Sweden Report number: 2013.2.4 Written by: Louise Wintzell, Ti10, [email protected] Abstract Noise has become an increasing public health problem and has become serious environment pollution in our daily life. This indicates that it is in time to control and reduce noise from traffic and installations in homes and houses. Today a plethora of products are available for business, but none for the private market. The project describes a start up of development of a sound absorbing wall panel for the private market. It will examine whether it is possible to make a wall panel that can lower the sound pressure level with 3 dB, or reach 0.3 s in reverberation time, in a normally furnished bedroom and still follow the demands of price and environmental awareness. To start the project a limitation was made to use the textiles available per meter within the range of IKEA. The test were made according to applicable standards and calculation of reverberation time and sound pressure level using Sabine’s formula and a formula for sound pressure equals sound effect. During the project, tests were made whether it was possible to achieve a sound classification C on a A-E grade scale according to ISO 11654, where A is the best, with only textiles or if a classic sound absorbing mineral wool had to be used. To reach a sound classification C, a weighted sound absorption coefficient (αw) of 0.6 as a minimum must be reached. -
Making It Sound As Good As It Tastes: Noise Reverberation Reduction in a Micro Distillery Tasting Room Andrew Sheehy Montana Tech of the University of Montana
Montana Tech Library Digital Commons @ Montana Tech Graduate Theses & Non-Theses Student Scholarship Spring 2016 Making it Sound as Good as it Tastes: Noise Reverberation Reduction in a Micro Distillery Tasting Room Andrew Sheehy Montana Tech of the University of Montana Follow this and additional works at: http://digitalcommons.mtech.edu/grad_rsch Part of the Occupational Health and Industrial Hygiene Commons Recommended Citation Sheehy, Andrew, "Making it Sound as Good as it Tastes: Noise Reverberation Reduction in a Micro Distillery Tasting Room" (2016). Graduate Theses & Non-Theses. 89. http://digitalcommons.mtech.edu/grad_rsch/89 This Publishable Paper is brought to you for free and open access by the Student Scholarship at Digital Commons @ Montana Tech. It has been accepted for inclusion in Graduate Theses & Non-Theses by an authorized administrator of Digital Commons @ Montana Tech. For more information, please contact [email protected]. 1 Making it Sound as Good as it Tastes: Noise Reverberation Reduction in a Micro Distillery Tasting Room Andrew John Sheehy, Dan Autenrieth, Julie Hart, and Scott Risser Montana Tech Publishable Paper submitted to Artisan Spirit Magazine 2 Abstract Noise reverberation in micro distillery tasting rooms can interfere with speech communication and negatively impact the acoustic quality of live music. Noise reverberation was characterized in a tasting room in Butte, MT by calculated and quantified methods. Sound absorbing baffles were then installed in an effort to reduce reverberation and improve room acoustics. The overall reverberation time and speech interference level were decreased by measureable amounts that corresponded with an increase in overall absorption in the space. Reverberation time decreased from 0.85 seconds to 0.49 seconds on average. -
Reverb 101: Room Reverberation and Better Listening Experiences
Reverb 101: Room Reverberation and Better Listening Experiences A great listening experience involves more than just high-quality audio equipment—the way sound moves around the room matters just as much. You don’t have to be an expert acoustician to create an impressive listening environment —just an understanding of some basic acoustic concepts will get you well on your way. The Basics of Reverberation Reverberation (or reverb) is important to think about when planning the acoustical treatments for your room. To define reverb, we first need to understand how sound travels from the source to your ear. When sound is emitted, sound waves take off in every direction. Some waves will travel the straight path from the source to your ear, and the rest will bounce around the room, ricocheting off of hard surfaces until they reach your ear or lose steam and die out. You hear the unadulterated direct sound first—then you start hearing indirect sounds as they arrive. Given that sound travels roughly 770 miles per hour, this happens very fast, and your brain interprets all the copies of sound together as one. The ratio of direct and indirect sounds determines the sound quality. That is where reverberation comes in. Reverberation is the collection of indirect sounds in an enclosed space. The more sound copies that pile up, the muddier the sound becomes. How Does Reverberation Affect the Listening Experience? When direct sound and reverberation combine in a favorable ratio, the sound is rich and full. The effect can bring music to life and even smooth out transitions between musical notes, creating a pleasant, desirable sound. -
Vern Oliver Knudsen Papers LSC.1153
http://oac.cdlib.org/findaid/ark:/13030/kt109nc33w No online items Finding Aid for the Vern Oliver Knudsen Papers LSC.1153 Finding aid updated by Kelly Besser, 2021. UCLA Library Special Collections Finding aid last updated 2021 March 29. Room A1713, Charles E. Young Research Library Box 951575 Los Angeles, CA 90095-1575 [email protected] URL: https://www.library.ucla.edu/special-collections Finding Aid for the Vern Oliver LSC.1153 1 Knudsen Papers LSC.1153 Contributing Institution: UCLA Library Special Collections Title: Vern Oliver Knudsen papers Creator: Knudsen, Vern Oliver, 1893-1974 Identifier/Call Number: LSC.1153 Physical Description: 28.25 Linear Feet(57 document boxes, and 8 map folders) Date (inclusive): circa 1922-1980 Abstract: Vern Oliver Knudsen (1893-1974) was a professor in the Department of Physics at UCLA before serving as the first dean of the Graduate Division (1934-58), Vice Chancellor (1956), Chancellor (1959). He also researched architectural acoustics and hearing impairments, developed the audiometer with Isaac H. Jones, founded the Acoustical Society of America (1928), organized and served as the first director of what is now the Naval Undersea Research and Development Center in San Diego, and worked as a acoustical consultant for various projects including the Hollywood Bowl, the Dorothy Chandler Pavilion, Schoenberg Hall, the United Nations General Assembly building, and a variety of radio and motion picture studios. The collection consists of manuscripts, correspondence, galley proofs, and other material related to Knudsen's professional activities. The collection also includes the papers of Leo Peter Delsasso, John Mead Adams, and Edgar Lee Kinsey. -
Web-Based Psychoacoustics: Hearing Screening, Infrastructure, And
bioRxiv preprint doi: https://doi.org/10.1101/2021.05.10.443520; this version posted May 11, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. Web-based Psychoacoustics: Hearing Screening, Infrastructure, and Validation Brittany A. Moka, Vibha Viswanathanb, Agudemu Borjiginb, Ravinderjit Singhb, Homeira Kafib, and ∗Hari M. Bharadwaja,b aDepartment of Speech, Language, and Hearing Sciences, Purdue University, West Lafayette, IN, United States bWeldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States Abstract Anonymous web-based experiments are increasingly and successfully used in many domains of behavioral research. However, online studies of auditory perception, especially of psychoacoustic phe- nomena pertaining to low-level sensory processing, are challenging because of limited available control of the acoustics, and the unknown hearing status of participants. Here, we outline our approach to mitigate these challenges and validate our procedures by comparing web-based measurements to lab- based data on a range of classic psychoacoustic tasks. Individual tasks were created using jsPsych, an open-source javascript front-end library. Dynamic sequences of psychoacoustic tasks were imple- mented using Django, an open-source library for web applications, and combined with consent pages, questionnaires, and debriefing pages. Subjects were recruited via Prolific, a web-based human-subject marketplace. Guided by a meta-analysis of normative data, we developed and validated a screening pro- cedure to select participants for (putative) normal-hearing status; this procedure combined thresholding of scores in a suprathreshold cocktail-party task with filtering based on survey responses. -
Musical Elements in the Discrete-Time Representation of Sound
0 Musical elements in the discrete-time representation of sound RENATO FABBRI, University of Sao˜ Paulo VILSON VIEIRA DA SILVA JUNIOR, Cod.ai ANTONIOˆ CARLOS SILVANO PESSOTTI, Universidade Metodista de Piracicaba DEBORA´ CRISTINA CORREA,ˆ University of Western Australia OSVALDO N. OLIVEIRA JR., University of Sao˜ Paulo e representation of basic elements of music in terms of discrete audio signals is oen used in soware for musical creation and design. Nevertheless, there is no unied approach that relates these elements to the discrete samples of digitized sound. In this article, each musical element is related by equations and algorithms to the discrete-time samples of sounds, and each of these relations are implemented in scripts within a soware toolbox, referred to as MASS (Music and Audio in Sample Sequences). e fundamental element, the musical note with duration, volume, pitch and timbre, is related quantitatively to characteristics of the digital signal. Internal variations of a note, such as tremolos, vibratos and spectral uctuations, are also considered, which enables the synthesis of notes inspired by real instruments and new sonorities. With this representation of notes, resources are provided for the generation of higher scale musical structures, such as rhythmic meter, pitch intervals and cycles. is framework enables precise and trustful scientic experiments, data sonication and is useful for education and art. e ecacy of MASS is conrmed by the synthesis of small musical pieces using basic notes, elaborated notes and notes in music, which reects the organization of the toolbox and thus of this article. It is possible to synthesize whole albums through collage of the scripts and seings specied by the user. -
The Room Acoustics of Large Spaces
ROOMROOM ACOUSTICSACOUSTICS OFOF LARGELARGE SPACESSPACES TheThe TalaskeTalaske Group,Group, inc.inc. The Room Acoustics of Large Spaces Presented by: Rick Talaske The Talaske Group, inc. Oak Park, IL – U.S.A. ASA Tutorial Cancun, Mexico The photos of all projects are designed by The Talaske Group, inc. Presented to the Acoustical Society of America – Cancun, Mexico 02 December 2002 ROOMROOM ACOUSTICSACOUSTICS OFOF LARGELARGE SPACESSPACES TheThe TalaskeTalaske Group,Group, inc.inc. Acoustically speaking: What is a “Large” Room It is my pleasure to present this discussion in Cancun regarding the acoustics of large rooms. Generally, this topic is what the public thinks of when they hear the word “acoustics”. This is because of their experiences in churches, theatres and music halls. I hope to better your understanding about this interesting topic. Es un placer de estar aqui en Cancun y al al vez hacer un presentacion sobre la acustica en grandes espacios. Generalmente, la gente cada vez que se menciona la palabra “acusticaq”, la relacionan con iglesias, teatros ysalas musicales. Espero de que en esta presentacion, ustedes se lleven un mejor entendimiento del concepto de acustica. Presented to the Acoustical Society of America – Cancun, Mexico 02 December 2002 ROOMROOM ACOUSTICSACOUSTICS OFOF LARGELARGE SPACESSPACES TheThe TalaskeTalaske Group,Group, inc.inc. Acoustically speaking: What is a “Large” Room In this paper, a large room: • Schroeder’s Frequency is less than 50 Hz •fc = 2000*SR ( T60/V ) •fc is below the voice and music bandwidth. • Comb filtering is a lesser consideration. • Un espacio grande es un cuarto con muchas resonancias normales. Hay tantas resonancias que finalmente no son tan importantes. -
Paper One the Standing Wave Problem
LeadingEdge Systematic Approach Room Acoustic Principles - Paper One The Standing Wave Problem Sound quality problems caused by poor room acoustics. We all recognise that room acoustics can cause sound quality problems. But often the issues are not clearly described or discussed. Here we will cover some important considerations and principles of room acoustics problems. Treating your room should not be done in isolation from all the other system building considerations. Your thoughts about room acoustics treatment should be in conjunction with your requirements for mains, supports, system electronics, speakers and cables etc. None of these should be dealt with in isolation, and with regards to room acoustics it’s particularly important to be aware of some of the interactive nature of room acoustics, and other systematic faults. For example, a boomy bass could be caused by a room mode, but equally it could be caused by bass feedback from a wall and up into your system through the mains leads. If it’s your mains cables feeding back vibration that’s the dominant problem, spending money on room treatment may not correctly resolve the issue. Room acoustics problems can be grouped into the following categories. 1. Air mass problems: – Standing waves with sound pressure peaks and suck-outs (and associated velocity peaks) – Velocity generated intermodulation 2. Reflection problems – Unwanted reflected signals at the listening position – Raised reverberant background noise floor The behavior of a room’s air mass is the most important consideration with room treatment. A significant air mass problem is a fundamental destroyer of performance - uncontrolled room modes produce associated velocity intermodulation, which damages every aspect of musical reproduction. -
Acoustics 101 for Architects a Presentation of Acoustical Terminology and Concepts Relating Directly to the Design and Construction of an Architectural Space
Acoustics 101 for Architects A presentation of acoustical terminology and concepts relating directly to the design and construction of an architectural space. Low-tech descriptions, explanations, and examples. By: Michael Fay This essay is tailored to the one group of people who have more influence over a building's acoustics than any other; architects. The focus is on Architectural Acoustics, a field that is broader than most imagine. To do justice to the theme, we must briefly touch on many subordinate topics, most having a synergetic relationship bonding architecture and sound. This paper is based on fundamentals, not perfection. It covers most of the basics, and explores many modern and esoteric matters as well. You will be introduced to interesting and analytical subjects; some you may know, some you may never have considered. Here are a few examples of what you'll find by reading on: . What is sound and why is it so hard to manage or control? . The length of low- and high-frequency sound waves vary by as much as 400:1. Why does this disparity matter? . How and why do various audible frequencies behave differently when interacting with various materials, structures, shapes and finishes? . There are three acoustical tools available to both the architect and the acoustician. What are they? How can they benefit or hinder the work of each craft? . Room geometry: Why some shapes are much better than others. Examples and explanations. Reverberation and echo: How do they differ? Which is better, or worse, and why? How much is too much, or too little? .