An array of four microphones ready for noise measurements. Credit: Kent Gee
WASHINGTON, Feb. 14, 2023 – When the Artemis 1 mission was launched by NASA’s Space Launch System, SLS, in November, it became the world’s most powerful rocket, exceeding the thrust of the previous record holder, Saturn 5, by 13%. With liftoff came a loud roar heard miles away. In JASA Express Letters, published on behalf of the Acoustical Society of America by AIP Publishing, researchers from Brigham Young University and Rollins College in Florida reported…click to read more
The NASA Quesst mission will fly a supersonic aircraft over various communities to test noise-mitigating technology.
Media Contact: Ashley Piccone AIP Media 301-209-3090 media@aip.org
NASHVILLE, Tenn., Dec. 6, 2022 – Supersonic aircraft generate a series of shock waves that merge into two distinct booms. The planes drag these incredibly loud sounds along their flight path, creating unacceptable noise levels over land. So far, sonic booms have prevented commercial supersonic flight over land, but fixing the noise could cut flight times in half.
NASA’s X-59 aircraft will fly over communities to test supersonic flight without the sonic boom. Credit: NASA
At the 183rd Meeting of the Acoustical Society of America, Gautam Shah of NASA Langley Research Center will present “NASA’s Quesst mission—Community Response Testing Plans,” in which he will discuss the plans to test a supersonic aircraft with technology to reduce sonic booms. The presentation will take place on Dec. 6 at 10:50 a.m. Eastern U.S. in the Summit B room, as part of the meeting running Dec. 5-9 at the Grand Hyatt Nashville Hotel.
“NASA’s X-59 aircraft is intended to validate and demonstrate the design tools and technologies that make it possible to design an aircraft with a different shape that alters how supersonic shock waves behave,” said Shah. “Instead of coming together to be heard as a loud boom, the shock waves do not merge. They rapidly weaken, resulting in a sound more like a soft thump.”
NASA will conduct a series of flights over various communities across the U.S. Shah and his team will measure the sound of the aircraft and conduct public surveys to understand the public response to different noise levels. By providing this information to regulatory agencies, the group hopes to inform an overland supersonic sound standard.
The first flight will take place in 2023, followed by 18 months of testing to confirm the aircraft’s performance and safety. From 2025 through 2026, NASA intends to conduct a series of four to six community tests at locations across the country, eventually delivering the data to regulators in 2027.
ASA PRESS ROOM 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/.
LAY LANGUAGE PAPERS ASA will also share dozens of lay language papers about topics covered at the conference. Lay language papers are 300 to 500 word summaries of presentations written by scientists for a general audience. They will be accompanied by photos, audio, and video. Learn more at https://acoustics.org/lay-language-papers/.
PRESS REGISTRATION 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.
ABOUT THE ACOUSTICAL SOCIETY OF AMERICA 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/.
Shhhh … Speaking More Quietly in Restaurants Means Everyone Can Be Heard #ASA183
In restaurants and at parties, the tendency is to talk louder to get your message across. Unfortunately, it does just the opposite.
Media Contact: Ashley Piccone AIP Media 301-209-3090 media@aip.org
NASHVILLE, Tenn., Dec. 5, 2022 – In a crowded restaurant, diners usually talk with their companions at their own table. But the sound of their conversations bounces off walls and reflects to other patrons, creating background noise. Each individual speaker wants to be heard over that noise, so they end up talking a little bit louder, which again increases the overall din. Eventually – barring an interruption – the system gets loud enough to reach the limit of the human voice.
A busy restaurant grows louder and louder because of the Lombard effect. Image Catalog via Flickr
Braxton Boren of American University will discuss this cycle, called the Lombard effect, and how it can be disrupted in his presentation, “A game theory model of the Lombard effect in public spaces.” The presentation will take place Dec. 5 at 12:40 p.m. Eastern U.S. in the Summit B room, as part of the 183rd Meeting of the Acoustical Society of America running Dec. 5-9 at the Grand Hyatt Nashville Hotel.
Game theory metaphors, such as the prisoner’s dilemma or the unscrupulous diner’s dilemma, can provide a good model for the Lombard effect. Boren used such mathematical models to construct the payoffs and incentives for the Lombard effect across different sound frequencies of the human voice.
“This effect is an example of the Tragedy of the Commons, which is a term often used in environmental science and economics for the way that individuals are incentivized to misuse public goods,” he said. “In the case of the Lombard effect, the quiet background (which allows for conversations to be intelligibly understood) is the commons, and each speaker in the room is incentivized to take a little bit more of that quiet space for his/her own conversation.”
Technology solutions, like smart earbuds, may eventually be able to individualize conversations by homing in on a single speaker. Understanding the acoustics and altering the absorption of walls in a space could also minimize the Lombard effect.
“Based on our understanding of this phenomenon, it is possible to design rooms that increase or decrease Lombard-related crowd noise in public settings,” said Boren. “But in a loud situation, I encourage people to try talking quietly while everyone else around them is shouting. Then, when that doesn’t work, go home and rest your ears!”
ASA PRESS ROOM 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/.
LAY LANGUAGE PAPERS ASA will also share dozens of lay language papers about topics covered at the conference. Lay language papers are 300 to 500 word summaries of presentations written by scientists for a general audience. They will be accompanied by photos, audio, and video. Learn more at https://acoustics.org/lay-language-papers/.
PRESS REGISTRATION 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.
ABOUT THE ACOUSTICAL SOCIETY OF AMERICA 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/.
Olivia C Coiado – coiado@illinois.edu
Twitter: @oliviacoiado
Instagram: @oliviacoiado
Department of Biomedical and Translational Sciences, Carle Illinois College of Medicine, Department of Bioengineering, University of Illinois Urbana-Champaign, Urbana, Illinois, 61801, United States
Erasmo F. Vergara
Laboratory of Vibration and Acoustics, Department of Mechanical Engineering, Federal University of Santa Catarina, Florianópolis, SC, Brazil.
Lizandra G. Lupi Vergara
Laboratory of Ergonomics, Department of Production and Systems Engineering, Federal University of Santa Catarina, Florianópolis, SC, Brazil.
Popular version of 3pNS4-Noise Pollution in Hospitals and its Impacts on the Health Care Community and Patients, presented at the 183rd ASA Meeting.
If you ever had to be hospitalized in your life, you probably know that spending a night in a hospital room and getting some sleep is almost an impossible mission! Why? Noise in hospitals is a common problem for patients, families and teams of professionals and employees. Most of a hospital’s environment is affected by the sounds of equipment and machines with high sound pressure levels (SPL) or “noise”.
What can we do?
Fig 1: Sound pressure meter positioned in front of the reception desk in Brazil.
We used a sound pressure meter (Fig. 1) to record noise of medical equipment such as machines, medical devices, tools, alarms used in the medical activities in hospitals in Brazil and in the United States. SPLs inside hospitals may have high average values, higher than 60 decibels (dB), with peak SPL values of 100 dB and may not meet the international requirements. The World Health Organization (WHO) suggests that the average SPL in hospitals should be around 35 dB during the day and 30 dB at night. SPLs above 65 dB can cause behavioral disorders and affect the quality of sleep and cause changes in the physiological responses to stress in hospitalized patients. High noise levels exceeding 55 dB can affect both patients and staff. The noise effects can cause memory lapses and mental exhaustion in performing tasks, exposing technical and support teams to risks, accidents and errors in the performance of their work. For instance, a plane taking off (Fig. 2) can reach up to 100 dB and a noisy hospital environment can reach up to 70 dB, more than double of the noise recommended by the WHO!
Figure 2: Image adapted from Bayo, Garcia and Garcia 1989.
Our research considered both quantitative aspects, through numerical and qualitative descriptors (subjective and psychological assessment of patients, medical staff, employees, etc.), to assess noise pollution in hospitals. Our model analyzed the relationship between the acoustic characteristics of the environment and people’s sound perception.
We interviewed 47 people in a Brazilian Hospital, the responses were collected from nurses, nursing assistants, doctors, and other staff members. 60% of the participants responded that they needed to speak louder and felt discomfort with the noise in the work environment, 57% said they felt discomfort with the noise coming from the medical equipment, 72% of the participants said the work environment is moderately or very noisy. The next phase of our research is to repeat the same measurements in a United Stated Hospital and compare the results. Then we can make a reflection, what can we do to reduce the effects of noise pollution in hospitals? How to reduce the noise coming from medical equipment? Our “dream” is to provide a more comfortable environment for patients and the health community. Hoping they can finally get a good night of sleep in Brazil in the U.S or any other hospital in the world.
Daniel Fink – djfink01@aol.com
Twitter: @QuietCoalition
Board Chair, The Quiet Coalition, 60 Thoreau Street Suite 261, Concord, MA, 01742, United States
The Quiet Coalition is a program of Quiet Communities, Inc.
Popular version of 3pNS1-What is the safe noise level to prevent noise-induced hearing loss?, presented at the 183rd ASA Meeting.
Ear structures including outer, middle, and inner ear. Image courtesy of CDC
If something sounds loud, it’s too loud, and your auditory health is at risk. Why? The safe noise exposure level to protect your hearing- to prevent noise-induced hearing loss (NIHL) and other auditory disorders like tinnitus, also known as ringing in the ears, might be lower than you think. Noise damages delicate structures in the inner ear (cochlea). These include minuscule hair cells that actually perceive sound waves, transmitted from the air to the ear drum, then from bones to the fluid in the cochlea.
Figure 1. Normal hair cells (left) and hair cells damaged by noise (right). Image courtesy of CDC
[A little detail about sound and its measurement. Sound is defined as vibrations that travel through the air and can be heard when they reach the ear. The terms sound and noise are used interchangeably, although noise usually has a connation of being unpleasant or unwanted. Sound is measured in decibels. The decibel scale is logarithmic, meaning that an increase in sound or noise levels from 50 to 60 decibels (dB) indicates a 10-times increase in sound energy, not just a 20% increase as might be thought. A-weighting (dBA) is often used to adjust unweighted sound measurement to reflect the frequencies heard in human speech. This is used in occupational safety because the inability to understand speech after workplace noise exposure is the compensable industrial injury.]
Many audiologists still use the industrial-strength 85 dB noise level as the level at which auditory damage begins. This is incorrect. The 85 dBA noise level is the National Institute for Occupational Safety and Health (NIOSH) recommended occupational noise exposure level (REL). This does not protect all exposed workers from hearing loss. It is certainly not a safe noise level for the public. Because of the logarithmic decibel scale, 85 decibel sound has approximately 30 times more sound energy than the Environmental Protection Agency’s 70 decibel safe sound level, not about 20% as might be thought.
The EPA adjusted the NIOSH REL for additional exposure time- 24 hours a day instead of only 8 hours at work, 365 days a year instead of 240 days- to calculate that 70 dB average noise exposure for a day would prevent noise-induced hearing loss. This is the only evidence-based safe noise level I have been able to find.
But the real safe noise level to prevent NIHL must be lower than 70 dB. Why? EPA used the 40-year occupational exposure in its calculations. It didn’t adjust for lifetime exposure (approaching 80 years in the United States before the COVID pandemic). NIHL comes from cumulative noise exposure. This probably explains why so many older people have trouble hearing, the same way additional years of sun exposure explains the pigmentation changes and wrinkles in older people.
My paper explains that the NIOSH REL, from which EPA calculated the safe noise level, was based on studies of workers using limited frequency audiometry (hearing tests), only up to 4000 or 6000 Hertz (cycles per second). More sensitive tests of hearing, such as extended-range audiometry up to 20,000 Hertz, shows auditory damage in people with normal hearing on standard audiometry. Tests of speech in noise- how well someone can hear when background noise is added to the hearing test- also show problems understanding speech, even if standard audiometry is normal.
The actual noise level to prevent hearing loss may be as low as 55 dBA. This is the noise level needed for the human ear to recover from noise-induced temporary threshold shift, the muffling of sound one has after exposure to loud noise. If you’ve ever attended a rock concert or NASCAR race and found your hearing muffled the next morning, that’s what I’m talking about. (By the way, there is no such thing as temporary hearing loss. The muffling of sound, or temporary ringing in the ears after loud noise exposure, indicates that permanent auditory damage has occurred.)
55 dB is pretty quiet and would be difficult to achieve in everyday life in a modern industrialized society, where average daily noise exposures are near 75 dB. But I hope that if people know the real safe noise level to prevent hearing loss, they will avoid loud noise or use hearing protection if they can’t.
The American Public Health Association states, “Noise is unwanted and/or harmful sound.” Noise not loud enough to damage hearing causes high blood pressure, heart attacks, and strokes. The Federal Aviation Administration (FAA) considers noise an annoyance but does not acknowledge the adverse health effects of aircraft noise. Based on the Schultz curve, the FAA adopted 65 dBA Day-Night Level (DNL) as “the threshold for significant aviation noise, below which residential land use is compatible.” The FAA’s recent Neighborhood Environmental Survey found that many more Americans are annoyed by noise than previously known.
Schultz Curve and Neighborhood Environmental Survey results, showing that many more Americans are annoyed by noise than the Schultz Curve showed. Source: FAA
[I have to tell you a little about the science of sound or noise measurement. The words sound and noise are used interchangeably. Sound is measured in decibels (dB). The decibel scale is logarithmic. This means that a 10 dB increase from 50 to 60 dB indicates 10 times more sound energy, not merely 20% more. Because noise disrupts sleep, DNL measures noise for 24 hours but adds a 10 dB penalty for noise between 10 p.m. and 7 a.m. A-weighting (dBA) adjusts sound measurements for the frequencies heard in human speech. A-weighting is not the right measure for aircraft noise because aircraft noise has lower frequencies than speech. A-weighting also reduces unweighted sound measurements by about 20-30 dB.]
According to the Environmental Protection Agency (EPA), though, safe noise levels are only 45 dB DNL for indoor noise and 55 dB DNL for outdoor noise. The World Health Organization (WHO) recommends lower aircraft noise levels: 45 dB Day-Evening-Night Level (adding a 5 dB penalty for noise between 7-10 p.m.) and 40 dB at night. Both EPA safe noise levels and WHO recommended aircraft noise levels are obviously much lower than the FAA’s 65 dBA DNL, especially because they use unweighted dB.
Being annoyed or disturbed by aircraft noise is stressful. Stress increases heart rate and blood pressure. Stress increases blood levels of stress hormones. Stress causes inflammation of the blood vessel lining. in turn causing cardiovascular disease, including hypertension and heart attacks, and other adverse health effects. Scientific experts think that the evidence is strong enough to establish causality, not merely a statistical association. Epidemiological studies demonstrating these effects have been confirmed by human and animal research. The biological mechanisms are now understood at the cellular, subcellular, molecular, and genetic levels. Aircraft noise also affects poor and minority communities more than others. Children are also more sensitive to damage from noise, which also interferes with learning.
The FAA insists that more research is needed, but no more research is needed to know that aviation noise is hazardous to health. The FAA must establish lower noise standards to protect Americans exposed to aircraft noise.
Fig 1: Sound pressure meter positioned in front of the reception desk in Brazil.
Figure 2: Image adapted from Bayo, Garcia and Garcia 1989.
Photo credit: 