In This Issue
Summer Bridge on Noise Control Engineering
June 15, 2021 Volume 51 Issue 2
What is the role of engineering practice, education, and standards in mitigating human-generated noise? The articles in this issue survey these aspects of the US noise landscape, and offer updates and useful resources.

Resources for Noise Control Engineering

Monday, June 14, 2021

Author: George C. Maling

Numerous resources are available to provide guidance for engineers and others in addressing noise concerns.

Human-made noise is ubiquitous in daily life, from the background hum of the computer or refrigerator to the drone of leafblowers, the passing roar of an overhead airplane, or the beeping of a backing truck. Distinct from background or transient noise, sustained exposure to high levels of noise constitutes a health hazard. In addition to causing loss of hearing, it can raise stress levels and contribute to high blood pressure (Rathner 2014). For these reasons experts, techniques, and resources are available to reduce noise levels and mitigate their impacts.

In the workplace, the National Institute for Occupational Safety and Health (NIOSH; part of the Centers for Disease Control and Prevention, CDC) has determined that noise levels above 85 dBA[1] pose a health ­hazard and that the hazard increases with exposure time (NIOSH 1998). The institute estimates that 22 million workers are exposed to hazardous noise.[2]

Maling figureIdeally, an individual skilled in noise control engineering should be involved during the design stage of a product or machine. But the reality is that problems with noise must often be solved in the field and sometimes by staff engineers who do not necessarily have training or experience in noise control engineering. This article identifies the many resources available to individuals and organizations that need to address noise problems.

Buy Quiet

“Buy quiet” programs encourage the purchase of quiet equipment. Government agencies and professional organizations have used these programs to reduce the sources and impacts of noise in workplaces as well as residences, public spaces, and national parks.

A decade ago the Technology for a Quieter America report (NAE 2010, p. 41) provided information on buy quiet programs and presented good reasons for noise specifications:

  • They help reduce hazardous noise levels, saving the costs of a hearing conservation program.
  • Speech communication in low-noise workplaces is much better than in those with high noise levels. Because no hearing protection is necessary, desired sounds such as announcements via public address systems can be clearly heard.
  • Low-noise workplaces promote safety (e.g., alarms are clearly audible).
  • Low-noise workplaces make it easier for workers to concentrate and reduce fatigue.
  • Low-noise workplaces are more productive and more comfortable.

Key Elements of a Buy Quiet Program

The five key elements of a buy quiet program are

  • selection of a metric to describe the noise emission,
  • selection of a measurement method,
  • specification of equipment operating conditions,
  • declaration of the noise emission value, and
  • verification.

Noise emission metrics: The metric widely used to describe noise emissions is the A-weighted sound power level of the product, and there are many national and international standards with detailed procedures on how to determine this quantity. A simplified version of this metric, the product noise rating (PNR), has been developed (Nobile 2011a,b). Figure 1 shows a modern version of the full label, with not only the PNR value for the particular product but also the overall PNR scale so that the purchaser can see at a glance how loud (or quiet) the product is. This version is being considered for roll-out by the Institute of Noise Control Engineering of the USA (INCE-USA).

The PNR is numerically equivalent to the A-­weighted sound power level but does not involve technical units. Such a rating might be more acceptable to ­buyers and producers of noise-emitting equipment. When published in product literature or on a website, the PNR would be displayed as a uniform, recognizable label. A condensed version of the PNR label or “logo” may be used when space is limited or for other applications.

Measurement methods: Measurement methods are well established in US and international standards, as discussed by Robert Hellweg (2021) in this issue.

Operating conditions: The operating conditions for the measurements must be specified.

Declaration and verification of the noise emission value: International standards specify how a noise emission value should be declared, taking into account measurement variation in a production series and between labora­tories. The publication of a new American National Standard on noise declaration and verification (ANSI 2020) strengthens the case for buy quiet programs in the United States.

Overview of Buy Quiet Programs

In the late 1990s and early 2000s, NASA began a buy quiet program largely through the efforts of Beth ­Cooper.[3] The program is available today as an online Buy Quiet Roadmap[4] that can guide efforts for industry; for example, a roadmap for construction firms has been developed (Nelson 2011).[5]

NIOSH strongly encourages industry sectors to establish their own buy quiet program and identifies components of such a program, including the following:

  • management support of a buy quiet policy, including a commitment to low-noise purchases, application of cost-benefit analysis in purchasing decisions, and, at the highest level, the purchase of quiet equipment regardless of cost; and
  • an inventory of the noise emissions of existing ­equipment.

With respect to costs, not only the purchase price but also lifecycle costs should be considered, such as health costs, lost productivity, and the costs of a hearing conservation program. According to NIOSH, “conservative estimates provide $100 per dBA of savings when purchasing a quieter product; this savings is applicable across a variety of machinery and equipment.”[6]

A database of noise emission values is also part of a buy quiet program. NIOSH developed a database of noise from power tools; other databases are also available:

  • IBM maintains information on the sound power level of its products to enable customers to determine noise levels in data processing centers.[7]
  • The European Union has noise requirements on construction equipment (European Parliament 2000) and maintains an extensive database of products and their declared noise emission values.
  • New York City has created a database of noise levels for construction equipment to provide guidance to contractors for using quiet equipment in city construction projects.
  • The Laborers Health and Safety Fund of North America also has information on products used in construction, with guidance on the selection of quiet saw blades and diesel generators.

The International Institute of Noise Control Engineering (I-INCE) develops reports on various noise ­topics. A recent report “outlines guidelines for ‘Buy Quiet’ programs to limit occupational noise and to assist professional buyers of industrial equipment” (Beltman et al. 2018, p. 5):

  • research by a buyer and seller on low-noise technology
  • establishment of a database of product noise emissions
  • selection of a noise emission standard and specification
  • determination of operating conditions
  • measurement and verification.

The report also reviews the history of such programs and includes a long list of references.

Online buy quiet roadmaps are available for construction and other industries.

Stakeholders in the Solution of Noise Problems

A number of professional and government organizations are available to assist industries with the control of noise sources.[8]

Professional Organizations

Institute of Noise Control Engineering of the USA

INCE-USA is dedicated to the solution of environmental, product, machinery, industrial, and other noise problems. It certifies members and other practitioners in noise control through a program of written material and an examination. It also publishes the peer-reviewed Noise Control Engineering Journal and, jointly with I-INCE, the magazine Noise/News International.

Mailing figure 2INCE-USA sponsors national conferences on noise control engineering (NOISE-CON) when inter­national (INTER-NOISE) congresses are held overseas. It also offers short courses on noise control at annual meetings as well as a distance learning program, maintains a digital library of noise publications (over 20,000 articles), and gives awards to both professionals and students. Many members offer consulting services in noise control engineering and architectural acoustics.

International Institute of Noise Control Engineering

I-INCE is a consortium of institutes of noise control engineering and acoustical societies around the world. It sponsors an annual INTER-NOISE congress and produces technical reports on various subjects related to noise control engineering (e.g., Beltman et al. 2018).

National Council of Acoustical Consultants

NCAC members offer consulting services for architectural acoustics, mechanical systems noise and vibration control, industrial workplace noise, environmental noise evaluation and control, product and system design, and forensic acoustics. The website has a reference tool to help visitors find a consultant matched to their need.

Other Professional Organizations

A number of associations in the United States address the broad field of acoustics and engineering and have noise control as part of their activities. They include the following:

  • Acoustical Society of America (ASA)
  • American Institute of Aeronautics and Astronautics (AIAA)
  • SAE International (formerly the Society of Automotive Engineers)
  • ASTM International (formerly the American Society for Testing and Materials)
  • American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE)
  • American Industrial Hygiene Association (AIHA)
  • American Conference of Government Industrial Hygienists (ACGIH)
  • National Hearing Conservation Association (NHCA)

Government Organizations

National Institute for Occupational Safety and Health

NIOSH conducts research on various aspects of workplace safety, including noise, and informs the public of the consequences of exposure to hazardous noise levels.

NIOSH’s recommended level for exposure to occupational noise is lower than that of the Occupational Safety and Health Administration (OSHA). The scientific basis for its recommendation of 85 decibels is the time-weighted average exposure for an 8-hour day (NIOSH 1998). The 1998 update of a 1972 document expands its guidance to include, among other things, the establishment of a hearing loss prevention program.

An earlier document (NIOSH 1978) may be useful when long-standing problems exist. Among other items, it provides advice on the analysis of noise problems and a long list of case histories for industrial noise control.

NIOSH advocates application of the hierarchy of controls, an inverted pyramid of actions to reduce noise exposures (figure 2). The pyramid gives preeminence to the elimination of hazardous sources of noise. If the source cannot be eliminated, then perhaps there is a substitute process that is less noisy. If elimination and substitution are not viable solutions, then engineering noise control solutions should be developed that will isolate the worker(s) from the noisy operation. Administrative controls can be used to limit the exposure times of workers to noisy operations. Finally, hearing protection devices are at the bottom of the pyramid. Together with administrative controls, they are considered less effective because they depend on individual worker compliance with the time limits for exposure and wearing hearing protection properly—if at all. Hence, noise control engineering is recommended as the primary method to control noise.

The NIOSH Safe-in-Sound Excellence in Hearing Loss Prevention and Innovation Award recognizes individuals and organizations that have proactively reduced hearing loss in occupational settings. The award program is administered in cooperation with the Council for Accreditation in Occupational Hearing Conservation and the National Hearing Conservation Association. The annual awards, for excellence and for innovation, have been presented to large industrial corporations, government agencies, military and law enforcement, and academic researchers.

In 2020 the award was given to an international consortium involved in efforts to control noise and protect hearing on the International Space Station, where astronauts are exposed to noise 24 hours a day, 7 days a week. The international group’s work to control noise and protect the astronauts’ hearing is accomplished in part through the purchase of quiet equipment and regular monitoring of noise in the station.

Occupational Safety and Health Administration

OSHA is the primary US regulatory body for limits on occupational noise exposure. It has produced a wealth of information on control of noise in industrial situations and has a strong interest in seeing noise levels reduced, even when they are below regulatory limits because such noise can affect communications between workers and contribute to stress, anxiety, high blood pressure, and fatigue. A particularly useful OSHA publication is the Technical Manual (OSHA 2013), in which chapter 5 details different kinds of noise, industries, regulations, noise controls, measurements, and references and resources.

OSHA has also announced the 2021 Safe+Sound program[9] for all aspects of workplace safety including noise, and offers consulting services for workplace issues independent of its regulatory program.

It is well established that exposure to hazardous noise produces hearing loss that is not reversible. Behind hypertension and arthritis, hearing loss is the most common chronic condition for adults. OSHA sets a permissible noise limit and also requires that an organization have a hearing conservation program when time-weighted average levels or average 8-hour levels exceed 85 dBA.

The OSHA permissible exposure limit for noise is 90 dBA with a 5 dB exchange rate. That means there is a trade-off between permissible level and time; for example, the limit would be 95 dBA for a 4-hour exposure, or 100 dBA for a 2-hour exposure. The OSHA manual allows a 10 dB increase if hearing-protective devices are used. But, as noted above, use of such devices is generally regarded as the last in a series of measures that should be used to control noise and reduce its impacts.

The OSHA limits are widely regarded as too permissive. For example, with regard to exposure to 85 dBA for 8 hours with an exchange rate of 3 dBA, OSHA’s sister organization, the Mine Safety and Health Administration (MSHA), has stated that scientific evidence in favor of these levels is strong.[10] Although the 85/3 dB criterion is generally accepted as a better limit for prevention of hearing loss, MSHA has not implemented a lower level mainly because of concerns about costs to small mining organizations.

Exposure to hazardous noise produces hearing loss
that is not reversible.

There is strong industry opposition to a reduction in the noise level permitted by OSHA, as illustrated by one attempt to change the noise exposure regulation. In 2011 OSHA issued a notice of proposed rule making that would change the definition of the word feasible as used in the noise regulations. Generally, the word has covered constraints such as schedules, costs, and ability to make changes. The new definition, based on a US Supreme Court definition in a case unrelated to noise emissions, defined feasible as “capable of being done.” The only constraint on the new definition as proposed for noise would be that the changes would not bankrupt a company required to lower noise levels. After considerable industry pressure on OSHA through the Small Business Administration and Congress, the proposal was withdrawn.

Environmental Protection Agency

The congressional Noise Control Act of 1972 ­directed the EPA’s Office of Noise Abatement and Control (ONAC) to regulate noise, including the purchase of low-noise-emission products,[11] and to issue information on product noise labeling.[12] The program never progressed enough to identify products that should be labeled (with the exception of portable air compressors, motorcycles, and hearing-protective devices). The procedures are still part of the Code of Federal Regulations, but in 1981 the office was defunded by the Reagan administration and that effectively ended EPA interest in buy quiet and low-noise products.

It may seem irrelevant to discuss events from almost 50 years ago, but the program resulted in the so-called “levels document” (EPA 1974), which defined noise levels to protect public health and welfare with an adequate margin of safety. Another output was demonstration projects that determined what could be done in the way of noise control (e.g., the low-noise design of trucks).

Some EPA noise regulations are a burden on manufacturers to meet
out-of-date standards that
do not account for modern noise control technology.

Some EPA noise regulations remain in place and are a burden on manufacturers to meet out-of-date standards that do not account for modern noise control technology. Such regulations affect motorcycles and air compressors, for example.

Other Government Agencies

Many federal and state agencies have noise programs. Federal agencies include the following (again, nonmilitary, nontransportation):

  • Department of the Interior (National Park Service)
  • Department of Energy
  • NIH National Institute on Deafness and Other Communication Disorders
  • CDC National Center for Environmental Health
  • CDC National Center on Birth Defects and Developmental Disabilities

Educational Institutions

Universities offer many resources for noise control engineering. Adnan Akay (2021) details what students should learn in such programs and cites specific subjects and areas of study.

In 2019 two workshops were held on the subject of noise control engineering education. The work of the participating organizations and universities is outlined in this issue (Wood and Maling 2021).

In addition, many entities such as universities, professional organizations, and consulting firms offer short courses on noise control, most frequently in conjunction with a conference.


There are numerous resources for noise control. This information should be especially useful for industry, where budgets cannot support one or more noise control engineers together with the facilities required for noise reduction. Companies may designate an engineer on staff to be responsible for noise control; with, perhaps, little or no training in noise control, that individual must look for resources. It is hoped that the information in this article will provide some guidance to assist individuals in becoming educated in the field.


Akay A. 2021. Noise control engineering and education. The Bridge 51(2):13–18.

ANSI [American National Standards Institute]. 2020. ANSI/ASA S12.61, American National Standard Declaration and Verification of Noise Emission Values of Machinery, Equipment, and Products. New York.

Beltman M, Hellweg R, Kurtz P, Tourret J, Jacques J. 2018. I-INCE TSG 10 Buy Quiet Report, rev. 0.98. Zürich: International Institute of Noise Control Engineering.

EPA [Environmental Protection Agency]. 1974. Information on levels of environmental noise requisite to protect public health and welfare with an adequate margin of safety. Prepared by the Office of Noise Abatement and Control. Washington.

European Parliament. 2000. Directive 2000/14/EC of the European Parliament and of the Council, 8 May. Official Journal of the European Communities L 162. Strasbourg.

Hellweg RD Jr. 2021. Voluntary national and international noise ­standards for products and machines. The Bridge 51(2):27–33.

NAE [National Academy of Engineering]. 2010. Technology for a Quieter America. Washington: National Academies Press.

Nelson D. 2011. Adaptation of NASA buy-quiet process roadmap for construction firms (NIOSH Publication 212-2011-M-38379). Washington: National Institute for Occupational Safety and Health.

NIOSH [National Institute for Occupational Safety and Health]. 1978. Industrial Noise Control Manual (Report 79-117). Cincinnati.

NIOSH. 1998. Criteria for a Recommended Standard: Occupational Noise Exposure, Revised Criteria (Publication 98-126). Cincinnati.

Nobile MA. 2011a. A simplified noise rating method for the general public. Proceedings, INTER-NOISE 2011, Sep 4–7, Osaka.

Nobile MA. 2011b. PNR: A simplified product noise rating for the general public. Presentation, NIOSH Buy Quiet Workshop, Nov 9–10. Online at 0247-110911-­nobile_pres.pdf.

OSHA [Occupational Safety and Health Administration]. 2013. Technical Manual, Section III, Chapter 5: Noise. Washington.

Rathner JL. 2014. Noise: Harmful to hearing, harmful to blood pressure. Washington: Laborers’ Health & Safety Fund of North America.

Wood EW, Maling GC Jr. 2021. A decade and a half of progress toward reducing noise in the United States. The Bridge 51(2):7–12.


[1]  Most noise levels are A-weighted; that is, the sounds are frequency weighted according to the A-weighting curve, which approximates human hearing for midlevel sounds. Note that it is the level and not the decibel that is A-weighted. Nevertheless, A-frequency-weighted levels are often expressed as dBA or dB(A).


[3]  Ms Cooper is an acoustical engineer who consults for NASA on hearing conservation, noise control engineering, and acoustics.

[4] process-roadmap/

[5]  In addition, an International INCE symposium in 2011 explored myriad dimensions of noise reduction (­buyquiet/buyquiet2011/index. htm).


[7]  IBM Knowledge Center, Power8: Acoustics,­support/knowledgecenter/POWER8/p8ebe/ p8ebe_acoustics.htm?mhsrc=ibmsearch_a&mhq=acoustic% 20noise%20declaration

[8]  Military organizations, those that deal with transportation noise, and other entities with less extensive programs are not included here.


[10]  Federal Register 61(243):66367 (1996).

[11]  Code of Federal Regulations 40 CFR §203: Low-Noise-­Emission Products,­-title40- vol25/CFR-2011-title40-vol25-part203

[12]  40 CFR §211: Product Noise Labeling, CFR-2002-title40-vol21-part211

About the Author:George Maling (NAE) is managing director emeritus of the Institute of Noise Control Engineering of the USA.