Taming Noise Behind Bars #Acoustics23

Taming Noise Behind Bars #Acoustics23

Prisons can be noisy places, but thoughtful design can lower stress and improve conditions for both staff and prisoners.

SYDNEY, Dec. 6, 2023 – Prisons are typically noisy environments, filled with clanking metal bars and echoing concrete surfaces. This level of constant noise is harmful to both prisoners and staff, but there are few guidelines for designing better, quieter facilities.

James Boland, an acoustician for SLR Consulting, employed insights from the field of sensory criminology to better understand the unique acoustic needs inside prison environments. His presentation will take place Dec. 6 at 2:40 p.m. Australian Eastern Daylight Time, as part of Acoustics 2023 Sydney, running Dec. 4-8 at the International Convention Centre Sydney.


Sound and noise inside prisons can affect both staff and inmates, so a thorough understanding of that noise is crucial when designing prison spaces. Credit: Helen Farley

“Sensory criminology examines how sensory experiences, such as sight, sound, and touch, influence and shape perceptions of crime and justice,” said Boland. “It emphasizes the impact of auditory elements on the experiences of both prisoners and staff and considers how the constant noise contributes to the overall atmosphere, perceptions, and communication within the prison environment.”

Auditory guidelines for prisons are often adapted from existing protocols for schools and hospitals. However, prisons are unique environments with different relationships to sound and noise. For instance, both prisoners and staff rely on noise to gauge the level of social tension. A prison that is ‘too quiet’ can sometimes be worse than one that is too loud.

In the context of prisons, acoustic design can contribute to transforming communication dynamics and alleviating negative social interactions. By focusing on speech intelligibility, strategic reduction of noise levels, and the incorporation of privacy considerations, acoustic design can significantly improve the overall prison environment. Creating distinct zones within the prison and balancing moments of quiet with activity are essential to fostering a more comfortable and secure space.

“The crux lies in recognizing the significance of ‘noise’ from the perspective of those inhabiting these spaces,” said Boland. “For prisoners, it’s about how sound influences their outlook in terms of power or dynamic safety in their daily lives, while for staff, it becomes a tool for decision-making and maintaining safety for themselves and those under their care.”

By seeking input from the people who occupy and live in these spaces, Boland hopes to gain an understanding of the complex role of sound inside prisons. Such an understanding could lead to better guidelines for current and future prison facilities, benefiting everyone inside.

“Ultimately, thoughtful acoustic design in prisons can directly influence the lived experiences of individuals, promoting positive social interactions and supporting rehabilitation efforts,” said Boland.


AIP Media


The Acoustical Society of America is joining the Australian Acoustical Society to co-host Acoustics 2023 Sydney. This collaborative event will incorporate the Western Pacific Acoustics Conference and the Pacific Rim Underwater Acoustics Conference.

Main meeting website: https://acoustics23sydney.org/
Technical program: https://eppro01.ativ.me/src/EventPilot/php/express/web/planner.php?id=ASAFALL23

In the coming weeks, ASA’s Press Room will be updated with newsworthy stories and the press conference schedule at https://acoustics.org/asa-press-room/.

ASA will also share dozens of lay language papers about topics covered at the conference. Lay language papers are summaries (300-500 words) of presentations written by scientists for a general audience. They will be accompanied by photos, audio, and video. Learn more at

ASA will grant free registration to credentialed and professional freelance journalists. If you are a reporter and would like to attend the meeting or virtual press conferences, contact AIP Media Services at media@aip.org. For urgent requests, AIP staff can also help with setting up interviews and obtaining images, sound clips, or background information.

The Acoustical Society of America (ASA) is the premier international scientific society in acoustics devoted to the science and technology of sound. Its 7,000 members worldwide represent a broad spectrum of the study of acoustics. ASA publications include The Journal of the Acoustical Society of America (the world’s leading journal on acoustics), JASA Express Letters, Proceedings of Meetings on Acoustics, Acoustics Today magazine, books, and standards on acoustics. The society also holds two major scientific meetings each year. See https://acousticalsociety.org/.

The Australian Acoustical Society (AAS) is the peak technical society for individuals working in acoustics in Australia. The AAS aims to promote and advance the science and practice of acoustics in all its branches to the wider community and provide support to acousticians. Its diverse membership is made up from academia, consultancies, industry, equipment manufacturers and retailers, and all levels of Government. The Society supports research and provides regular forums for those who practice or study acoustics across a wide range of fields The principal activities of the Society are technical meetings held by each State Division, annual conferences which are held by the State Divisions and the ASNZ in rotation, and publication of the journal Acoustics Australia. https://www.acoustics.org.au/

Curtains and drapes that can reduce noise pollution by more than half

Ben Cazzolato – benjamin.cazzolato@adelaide.edu.au

The University of Adelaide, Adelaide, SA, 5005, Australia

Cameron West
Acoustic Blinds and Curtains
Sydney, New South Wales, Australia

Tyler Schembri
The University of Adelaide
Forestville, South Australia, Australia

Peter Watkins
Acoustic Blinds and Curtains
Sydney, New South Wales, Australia

Will Robertson
The University of Adelaide
Forestville, South Australia, Australia

Popular version of 2pAA3 – Enhancing acoustic comfort with window coverings: Reducing sound transmission and reverberation times with a single product
Presented at the 185th ASA Meeting
Read the abstract at https://doi.org/10.1121/10.0023007

Please keep in mind that the research described in this Lay Language Paper may not have yet been peer reviewed.

Noise pollution isn’t just a nuisance, it’s bad for your health. Prolonged noise exposure has been linked to several short and long-term health problems – both physiological and psychological. The World Health Organization has estimated an annual loss of “at least one million healthy years of life” due to traffic noise alone.

Traditionally curtains and drapes have been used for design and light control only. However, they also present a great opportunity for a comprehensive acoustic treatment. This is for a number of reasons:

  1. They are installed over windows and glazing, which is where the sound commonly enters spaces;
  2. Windows generally have a significant surface area and are typically very reflective, which presents an opportunity to remove noise via absorption when covered;
  3. Unlike other acoustic treatments, they are a natural fit in most modern spaces allowing architects, designers and clients freedom in their design unconstrained by acoustics.

Extensive testing by qualified acoustic engineers in the Acoustic and Vibration Laboratories at the University of Adelaide, Australia have shown that it is possible to reduce noise pollution by more than half* with an acoustic interlining. The acoustic interlining is a mass layer that is sandwiched between two sound absorbing curtain fabrics. Together these layers block and absorb sound.

Figure 1: Measuring the sound transmission loss and sound absorption of an acoustic curtain in a reverberation chamber at the University of Adelaide.

The acoustic interlining was tested over four glazing conditions; open window, 4mm glass, 6.38mm glass and 10.38mm glass, across 15 different curtain configurations, totalling 76 tests. The plot below shows the reduction in sound pressure level in a receiving room when using a typical acoustic curtain as a room divider. In the plot we compare only using the interlining, using only the face fabrics, and the benefit of combining both face fabrics and interlining, with the latter providing a frequency-weighted improvement of 17dB. Similar results were obtained when the tests were repeated for the three thicknesses of glazing.

Figure 2: Reduction in sound pressure level (known as the level difference improvement) when using the acoustic curtains as a room divider.

We have generated two audio files demonstrating how these acoustic curtains reduce noise pollution: Room divider application using 1500gsm interlining, and 800gsm interlining over 4mm glazing applied to traffic noise.

Visit the Acoustic Blinds and Curtains website for more details on the curtain construction and informative videos demonstrating how these curtains reduce noise pollution and improve room acoustics.

Our testing has shown how curtains and drapes can reliably reduce noise pollution by more than half for both open and closed windows. This is a game-changer for architects and end-users looking for simple, cost effective noise reduction and sound absorption compared to other acoustic products and offer a functional alternative to traditional blinds and curtains.

*perceived noise reduction

Let’s go soundwalking!

David Woolworth – dwoolworth@rwaconsultants.net

Roland, Woolworth & Associates, Oxford, MS, 38655, United States

Bennett Brooks and Brigitte Schulte-Fortkamp

Popular version of 4pAAb1 – Introduction to Soundwalking – an important part of the soundscape method
Presented at the 185th ASA Meeting
Read the abstract at https://doi.org/10.1121/10.0023505

Please keep in mind that the research described in this Lay Language Paper may not have yet been peer reviewed.

Our acoustic environment is a critical part of our everyday experience; it is often unconsciously processed with all other stimuli to form an impression of a place and time, but its impact is not always fully understood. Soundscape is a method of assessing the acoustic environment where perception is prioritized. The soundscape method and the soundwalk tool integrate measurements of the human perception of sound with other observations that characterize the environment, such as the sound levels, the type of location and the various sound sources. The combination of these perceptual measurements with other observations helps us to understand how the acoustic environment impacts the people there and can provide directions for possible changes that can improve their quality of life.

The soundscape method suggests assessing all sounds which occur in an environment using collected data related to human perception, the physical acoustic setting, and context. Context includes visual cues, geographic, social, psychological and cultural aspects, including one’s mental image or memory of a place. Soundscape transcends the common studies of noise and sound levels, and is a powerful tool for effecting positive results with regard to the quality of life for stakeholders in the acoustic environment; standardized methodology has been developed that can be adapted to various applications, using sound as a resource. Soundwalks are an important part of the soundscape method and are a useful way to engage stakeholders who participate by consciously observing and evaluating the soundscape.

Figure 1

A soundwalk is an element of the soundscape method that typically will include a walking tour of observation locations over a predetermined route to solicit perceptual feedback from the participants regarding the acoustic environment (see Figures 1 and 2). The participants of the soundwalk typically include stakeholders or “local experts”: members of the community that experience the soundscape daily, users/patrons of a space, residents, business people, and local officials. Soundwalks can be performed from urban areas to wilderness settings, indoors and outdoors; the information collected can have many applications including ordinances and planning, preservation or improvement of the acoustic environment, and building public/self-awareness of the acoustic environment.

Figure 2

The perceptual information collected during a soundwalk includes the sounds heard by the participants and often directed questions with scaled answers; this along with objective sound level measurements and audio recordings can be used to assess an acoustic space(s) in an effort to effect the purpose of the soundwalk. (see Figures 3 and 4) In some cases, the participants are interviewed to get a deeper understanding of their responses or the data can be taken to a lab for further study.

Figure 3

The soundwalk and post processing of collected information is flexible relative to soundscape standard methods to target an acoustic space and purpose of the investigation. This makes it an adaptable and powerful tool for assessing an acoustic environment and improving the quality of life for the those that live in or use that environment, using their own perceptions and feedback.

Figure 4

Enhancing Museum Experiences: The Impact of sounds on visitor perception.

Milena J. Bem – jonasm@rpi.edu

School of Architecture, Rensselaer Polytechnic Institute, TROY, New York, 12180, United States

Samuel R.V. Chabot – Rensselaer Polytechnic Institute
Jonas Braasch – Rensselaer Polytechnic Institute

Popular version of 4aAA8 – Effects of sounds on the visitors’ experience in museums
Presented at the 185th ASA Meeting
Read the abstract at https://doi.org/10.1121/10.0023459

Please keep in mind that the research described in this Lay Language Paper may not have yet been peer reviewed.

Have you ever wondered how a museum’s subtle backdrop of sound affects your experience? Are you drawn to the tranquility of silence, the ambiance of exhibition-congruent sounds, or perhaps the hum of people chatting and footsteps echoing through the halls?

Museums increasingly realize that acoustics are crucial in shaping a visitor’s experience. There are acoustic challenges in museum environments, such as finding the right balance between speech intelligibility and privacy, particularly in spaces with open-plan exhibition halls, coupled rooms, high volumes, and highly reflective surfaces.

Addressing the Challenge
Our proposal focuses on using sound masking systems to tackle these challenges. Sound masking is a proven and widely used technique in diverse settings, from offices to public spaces. Conventionally, it involves introducing low-level broadband noise to mask or diminish unwanted sounds, reducing distractions.

Context is Key
In recognizing the pivotal role of context in shaping human perception, strategically integrating sounds as design elements emerges as a powerful tool for enhancing visitor experiences. In line with this, we propose using sounds congruent with the museum environment more effectively than conventional masking sounds like low-level broadband noise. This approach reduces background noise distractions and enhances artwork engagement, creating a more immersive and comprehensive museum experience.

Evaluating the Effects: The Cognitive Immersive Room (CIR)
We assessed these effects using the Cognitive Immersive Room at Rensselaer Polytechnic Institute. This cutting-edge space features a 360° visual display and an eight-channel loudspeaker system for spatial audio rendering. We projected panoramic photographs and ambisonic audio recordings from 16 exhibitions across five relevant museums — MASS MoCA, New York State Museum, Williams College Museum of Art, UAlbany Art Museum, and Hessel Museum of Art.

The Study Setup
Each participant experienced four soundscape scenarios: the original recorded soundscape in each exhibition, the recorded soundscape combined with a conventional sound masker, the recorded soundscape combined with a congruent sound masker, and “silence” which does not involve any recording, comprising the ambient room noise of 41 dB. Figure 1 shows one of the displays used in the experiment and below the presented sound stimulus.

Figure1: Birds of New York exhibition – New York State Museum. The author took the photo with the permission of the museum’s Director of Exhibitions.

Scenario 1: originally recorded soundscape in situ.
Scenario 2: recorded soundscape combined with a conventional sound masker.
Scenario 3: the recorded soundscape combined with a congruent sound masker.

After each sound stimulus, they responded to a questionnaire. It was applied through a program developed for this research where participants could interact and answer the questions using an iPad. After experiencing the four soundscapes, a final question was asked regarding the participants’ soundscape preference within the exhibition context. Figure 2 shows the experiment design.

Figure 2

Key Findings
The statistically significant results showed a clear preference for congruent sounds, significantly reducing distractions, enhancing focus, and fostering comprehensive and immersive experiences. A majority of 58% of participants preferred the congruent sound scenario, followed by silence at 20%, original soundscape at 14%, and conventional maskers at 8%.

Myth busted: classroom acoustics can be easy and cheap

Coralie van Reenen – cvreenen@csir.co.za

Council for Scientific and Industrial Research, Council for Scientific and Industrial Research, Gauteng, 0001, South Africa

Popular version of 3pAAb – Classroom acoustics: a case study of the cost-benefit of retrofitted interventions
Presented at the 185th ASA Meeting
Read the abstract at https://doi.org/10.1121/10.0023323

Please keep in mind that the research described in this Lay Language Paper may not have yet been peer reviewed.

Achieving the right acoustic conditions for classrooms is often dismissed by school planners as being too difficult or too expensive. This is to the detriment of students who are unable to hear the teacher properly, especially for children who are being taught in their second language, as is common in South Africa. This study proves that acoustic treatment need not be difficult or costly to achieve.

To refute the notion that acoustic improvements are expensive and specialized, this experimental case study was designed and carried out in a typical classroom in the small rural village of Cofimvaba in the Eastern Cape, South Africa. The ideal classroom environment has a low ambient noise level of 35 dB and a reverberation time below 0.7 seconds, but this classroom has a reverberation time of 1 second. Reverberation time refers to the time it takes for a noise to die down and essentially refers to how much a room echoes, which negatively affects speech clarity. The experimental intervention simulated the installation of floating ceiling islands by installing different materials on the roof of temporary gazebos in the classroom.

The four materials used were acoustic ceiling tiles which represent a typical solution and three DIY solutions using carboard egg cartons, thermal insulation batting, and sponge foam bed mattresses. Each material provided an improved reverberation time. The best performing was the sponge at 0.6 seconds, while the other three materials performed equally at 0.8 seconds.

The cost of each material was reduced to a rate per square meter. The most expensive material was the acoustic ceiling tiles at R 363.85/m2 while the cheapest was the egg cartons at R 22.22/m2, or less if they are available as waste items.

The availability of materials was evaluated in terms of the distance to supply and whether the product is available in a retail store or requires a special order and delivery. The batting is available from hardware stores nationwide and could be purchased by walk-in from the local hardware store, within a 2 km radius of the site. The egg cartons could be ordered online and delivered from a packaging company within a 150 km radius. The foam mattresses could be purchased by walk-in at a local retailer within a 5 km radius of the site. The acoustic ceiling tiles were ordered online and delivered from the warehouse within a 700 km radius of the site.

Using the weighted sum model and assigning equal weighting to each attribute of acoustic performance, cost, distance to supply, and walk-in availability, a performance score for each intervention material was calculated. The batting ranked number one, followed in order by the sponge, egg cartons and lastly acoustic tiles.

The case study demonstrates that an improvement in acoustic conditions of at least a 0.2 second reduction in reverberation time can be achieved without significant cost. Although the batting did not achieve the ideal reverberation time, when only the speech frequencies were considered, it fell within the recommended maximum of 0.7 seconds.

The recommended design intervention is a frame containing batting covered with a taught fabric and suspended from ceiling hooks, thus avoiding disruptive construction works. This shows that improved classroom acoustics can be achieved without high cost or technical difficulty.

A virtual reality system to ‘test drive’ hearing aids in real-world settings

Matthew Neal – mathew.neal.2@louisville.edu
Instagram: @matthewneal32

Department of Otolaryngology and other Communicative Disorders
University of Louisville
Louisville, Kentucky 40208
United States

Popular version of 3pID2 – A hearing aid “test drive”: Using virtual acoustics to accurately demonstrate hearing aid performance in realistic environments
Presented at the 184 ASA Meeting
Read the abstract at https://doi.org/10.1121/10.0018736

Many of the struggles experienced by patients and audiologists during the hearing aid fitting process stem from a simple difficulty: it is really hard to describe in words how something will sound, especially if you have never heard it before. Currently, audiologists use brochures and their own words to counsel a patient during the hearing aid purchase process, but a device often must be purchased first before patients can try them in their everyday life. This research project has developed virtual reality (VR) hearing aid demonstration software which allows patients to listen to what hearing aids will sound like in real-world settings, such as noisy restaurants, churches, and the places where they need devices the most. Using the system, patient can make more informed purchasing decisions and audiologists can program hearing aids to an individual’s needs and preferences more quickly.

This technology can also be thought of as a VR ‘test drive’ of wearing hearing aids, letting audiologists act as tour guides as patients try out features on a hearing aid. After turning a new hearing aid feature on, a patient will hear the devices update in a split second, and the audiologist can ask, “Was it better before or after the adjustment?” On top of getting device settings correct, hearing aid purchasers must also decide which ‘technology level’ they would like to purchase. Patients are given an option between three to four technology levels, ranging from basic to premium, with an added cost of around $1,000 per increase in level. Higher technology levels incorporate the latest processing algorithms, but patients must decide if they are worth the price, often without the ability to hear the difference. The VR hearing aid demonstration lets patients try out these different levels of technology, hear the benefits of premium devices, and decide if the increase in speech intelligibility or listening comfort is worth the added cost.

A patient using the demo first puts on a custom pair of wired hearing aids. These hearing aids are the same devices sold that are sold in audiology clinics, but their microphones have been removed and replaced with wires for inputs. The wires are connected back to the VR program running on a computer which simulates the audio in a given scene. For example, in the VR restaurant scene shown in Video 1, the software maps audio in a complex, noisy restaurant to the hearing aid microphones while worn by a patient. The wires send the audio that would have been picked up in the simulated restaurant to the custom hearing aids, and they process and amplify the sound just as they would in that setting. All of the audio is updated in real-time so that a listener can rotate their head, just as they might do in the real world. Currently, the system is being further developed, and it is planned to be implemented in audiology clinics as an advanced hearing aid fitting and patient counseling tool.

Video 1: The VR software being used to demonstrate the Speech in Loud Noise program on a Phonak Audeo Paradise hearing aid. The audio in this video is the directly recorded output of the hearing aid, overlaid with a video of the VR system in operation. When the hearing aid is switched to the Speech in Loud noise program on the phone app, it becomes much easier and more comfortable to listen to the frontal talker, highlighting the benefits of this feature in a premium hearing aid.