A Global Vision for the Noise Control Marketplace

Bennett M. Brooks,^a) T. James DuBois,^b) Robert M. Hoover,^c) George C. Mating,^d) and Louis C. Sutherland^e)

(Received 1996 April 18; revised 1996 May 06; accepted 1996 May 08)

Much progress has been made over the past 25 years in the United States to define the dangers of excessive noise exposure, and to develop the means to control it. A significant portion of this progress was stimulated by government actions to regulate the industries that produce noise, establish community and workplace noise standards, and to promote research and development in noise control. Today, the pressures of competition in the global marketplace, that did not exist 25 years ago, are rapidly increasing the motivation for noise control in the private sector. Those industries that seek to sell their products worldwide, particularly in Europe or Japan, find that they must meet stricter standards for noise than now exist in the U.S. Further, foreign companies that already live with such stricter standards are producing quiet products that compete for sales in the U.S. These challenges present both a threat to and an opportunity for U.S. commerce and industry. Several actions that can be taken immediately to address these issues are suggested. © 1996 Institute of Noise Control Engineering.

Primary subject classification: 87; Secondary subject classification: 67

1. INTRODUCTION

Product designers and manufacturers are increasingly being called upon to address the issues concerning the noise that their products generate. In the beginning of the noise control industry, the driving force for lower noise usually came from a direction other than the product user. Noise control was first applied to industrial installations as a result of complaints from neighbors, and later, as a result of pressure from government. Once the government became involved in regulating industry, the workers operating noisy machinery had a voice, but the owners of the machinery still had little interest in reducing noise levels. Noise control was generally seen as an expense, not a benefit. In the area of consumer products, noise was usually not an issue, because many users would equate noise with power. Also, consumers were not expected to be willing to pay a premium for a low noise product. In the past few years, a decidedly different trend has been developing. The pressure for product noise control is now coming increasingly from product users themselves. Those who buy industrial equipment and consumer products are now more aware of noise as an important factor in the purchasing decision. Noise levels are being included as a line item in equipment specifications for all types of industrial machinery, such as motors and pumps, where previously only the most superficial information was available. Noise specifications, along with function, price and delivery, play an increasing role in determining who wins the equipment order. In the realm of consumer products, low noise has become an effective marketing tool, for everything from automobiles to dishwashers.

As the competition for global markets has stiffened, low noise is yet another feature which manufacturers must offer in order to distinguish their product and attract buyers. A noise control marketplace has truly emerged.

Many product manufacturers have responded positively to the evolving market pressures for lower noise. However, many others have not yet addressed noise as an issue, or are only taking tentative steps to do so. These producers need to take action to develop their vision of a global marketplace, a marketplace which demands significant noise control. Otherwise, they may find their competition quietly taking away their business.

2. NOISE CONTROL - HISTORY OF GOVERNMENT ACTION

For more than a quarter century, government bodies at the federal, state and local levels have taken action aimed at limiting the exposure of citizens to excessive noise and its effects.^1-3

Beginning in the late 1960s, there was a flurry of federal legislation directed toward noise control. The National Environmental Policy Act of 1969 (NEPA) was a far reaching statement of national goals. This Act requires that all federal agencies consider the impact on the environment of any recommended action or legislation they may propose. It led to the creation of the Environmental Protection Agency (EPA). The Occupational Safety and Health Act of 1970 applied workplace noise standards to all businesses, in concert with its stated purpose '' ...to assure as far as possible every working man and woman in the nation safe and healthful working conditions and to preserve our human resources.''

The Clean Air Act of 1970 mandated the control of noise from motor vehicles and, further, established within the EPA an Office of Noise Abatement and Control (ONAC) to study the effects of noise from many sources on the public health and welfare. All of this legislative activity culminated in the Noise Control Act of 1972. Among other things, this Act established a policy that the United States control noise sources which would jeopardize public health and welfare. It gave broad authority to the EPA to establish noise standards, including noise emission standards for a wide range of products.

Motivated by this federal legislation, state governments began to write statutes that included noise control measures. Many of the states adopted laws controlling the noise emissions of automobiles and trucks. Some of the states also enacted regulations that limited the noise levels that may be caused by commercial or industrial operations, as measured at residential property lines. Following this lead, many municipalities also enacted noise laws that offered more protection than vague "nuisance ordinances.''

This 25-year legacy of govemment action resulted in what many people regard as significant advancements. It established a foundation for regulation of industry as applied to environmental noise emission. Also established, more clearly than before, were community and workplace noise standards. Further, the federal government funded important research and development, not only on the effects of noise, but also directed toward fostering the means to control noise.

Significant changes have taken place since the 1970s and early 1980s in the status of noise regulation enforcement. In the early 1980s the federal govemment declared noise to be a "local problem'' and funding for ONAC was discontinued. Also, there is now a changed emphasis at OSHA. While the noise regulations are still on the books, federal directives have weakened certain aspects of enforcement policy, such as the citation level for engineering controls. As a result, the number of citations for engineering control has dropped in recent years.4 Enforcement implementation is less uniform across the country, and becoming increasingly dependent on regional priorities, as inspectors with limited resources focus their efforts on problems thought to be more harmful to worker safety than excess noise exposure.

Similarly, budget limitations in many states have caused the suspension or closure of their noise control programs. This means that while many laws limiting noise still exist, there is often no one around in government to enforce them. With exceptions in some areas, such as air transportation, government in the U.S. is no longer as active as it once was in trying to protect its citizenry from noise.

3. GLOBALIZATION OF THE MARKETPLACE

It is recognized that business today is often conducted internationally. Many domestic and foreign manufacturers now acknowledge the need for a strong presence in the global marketplace, simply in order to survive. Global trade is a complex web encompassing all sons of manufactured products, including consumer goods, industrial and office equipment, automobiles and aircraft. Recent intemational agreements on trade enable companies to compete on the merit of their products, rather than with politics and tariffs. In both the American and overseas markets, competitive factors increasingly include emitted noise.

In the European Union (EU) low noise levels have been mandated by the EEC Machinery Safety Directive (1989)and its amendments (1991 and 1993). Further, these requirements are generally stricter than anything currently enforced in the U.S. In theory, no one will be able to sell products in EU markets without complying with the Machinery Directive and obtaining a "CE" marking.5,6

Although this agreement is not yet enforced widely, it will become more important in the future. National governments in the European Union, in response to complaints from local businesses, can be expected to direct enforcement activity toward competing non-EU producers. U.S. companies will have to be sure to meet EU noise requirements if they expect to gain a share of European markets. Moreover, since European manufacturers are already familiar with these noise requirements this advantage over U.S. manufacturers puts EU companies in a stronger competitive position.

Noise requirements are not limited only to products intended for the European market. U.S. markets increasingly demand low noise products as well. Large, highly visible projects still must meet the demands of sporadically enforced govemment noise regulations, and so must be built with quiet machinery components.

In addition, noise specifications are being placed in purchasing requisitions along with other requirements more than ever before. In today's competitive environment it is a buyer's market. Purchasers can, and do, demand more of a supplier. Today, purchasers have become aware of noise as a variable factor between equipment supplied by different vendors. Therefore, it is becoming more common that noise is weighed in the purchase decision equation together with traditional elements, such as functional performance, cost, delivery and maintenance. In a close decision, the low noise product wins!

Since European manufacturers have more experience with noise as a competitive factor, they also have an advantage over their U.S. counterparts in U.S. markets. Therefore, U.S. manufacturers face a tough challenge from competition that is better prepared to meet the low noise demands of both domestic and foreign customers.

4. INTERNATIONAL NOISE STANDARDS

In order to be sold legally in member countries of the European Union, equipment must meet safety requirements and carry the "CE" marking. These requirements are defined in the European Community Machinery Safety Directive from 1989 (89/392/EEC) and its amendments (91/368/EEC and 93/44/EEC). These documents address a wide range of safety issues with regard to the use of machines in the workplace, including noise emissions.5

The directive states (Section 1.5.8) that "Machinery must be so designed and that risks resulting from the airbome noise are reduced to the lowest level taking account of technical progress and the availability of means of reducing noise, in particular at (the) source.''

Other specific requirements of the Machinery Directive mandate that the supplier must indicate if the equivalent continuous A-weighted sound pressure level (LAeq) exceeds 70 dB at the equipment's workstations. Also, the supplier must indicate the emitted sound power of the machinery, if the LAeq at a workstation exceeds 85 dB.

Noise standards for the workplace, as defined by legislation, are generally less strict in the U.S. than in the rest of the industrialized world.7 Most of Europe limits the 8 hour workplace noise exposure to an LAeq of 85 dB, with a 3 dB exchange rate. By contrast, the U-S- (OSHA) still has a 90dB 8-hour exposure limit with a 5 dB exchange rate, although there have been serious efforts recently to make this requirement more strict.

Also, community noise standards throughout the industrialized world are generally more restrictive than they are in the U-S.8 Of particular interest to U.S. manufacturers are the noise standards for the transportation industry, including aircraft and road vehicles. For example, road side noise limits for heavy trucks are presently 6 dB lower in the EU, and 3 dB lower in Japan, than in the U-S- Further, the U.S. has no federally mandated noise requirements for passenger cars, while limits are becoming increasingly strict in the Eand Japan.9

The foregoing discussion of intemational noise standards is by no means all inclusive, but only intended to provide a view of the setting in which industry must operate. Clearly, manufacturers in the EU, due to their exposure to mandated noise limits, will be more attuned than their U.S. counterparts to the competitive issues of noise control.

5. COMPETITIVE EXAMPLES

Several examples of cases where noise control has been a key element in the development of a new product line are offered. These examples have in common the need of the manufacturer to compete on the basis of emitted noise levels. In some cases it is a U.S. manufacturer who meets this challenge, in others it is the overseas rival.

A. Garment industry

Those familiar with the anatomy of the corporate decision making process know that actions are sometimes taken on the basis of very little factual information. The need to reach the market in a timely manner with a competitive product may outweigh the desire for more complete technical data.

Such was the case for the U.S. manufacturer of large cloth cutting machines for the garment and automobile industries. This company's major competitors operate in France and Spain. The U.S. producer was motivated to undertake a major noise control effort on the basis of several factors.

First was a competitor's advertisement in the trade press claiming a noise level of "75 dB." No other information was given with regard to the location, frequency weighting, measured confirmation or even the reference unit of the cited level. Still, the U.S. machine maker wanted to match, or better, the competition. Against this background it was known that the U.S. built machines emitted A-weighted sound levels of 85 to 90 dB at the operator stations, and that there had been sporadic customer complaints about noise.

It is interesting to note that these cutting machines are old to customers worldwide, particularly in countries in South America and Southeast Asia, where there is little or no govemment regulation of workplace noise. Yet, emitted noise was considered a strong competitive factor. Part of the way through the design cycle of the next generation cutting machine model, major design modifications were developed with the goal of reducing noise emissions. Success was declared when an LAeq of 75 dB was measured during a test of the completed machine for company management on the factory assembly floor (Fig. I). Since then, the market demand for this model has been very strong, perhaps in part due to its much improved noise performance.

B. Gas pipeline equipment

A natural gas pipeline company supplying energy to east coast markets needed an additional compressor station along its route to meet growing demands. Unfortunately, the best location for this station was near an exclusive residential neighborhood. A series of private lawsuits brought by the residents blocked the development of the station for years. The emitted noise expected from such a station was a major factor in these lawsuits. Many development plans were submitted and rejected.

An American firm that supplies tumkey systems based on a European-built, low noise design, integral electric motor-driven compressor was brought in on the project. The first hurdle to overcome was to satisfy the objections of the neighbors and gain approval for the development plan. A new station plan was developed with low emitted noise level as a primary design requirement. This plan was based on measured noise data for a similar installation, and a building designed to contain any machine generated noise inside and to appear visually attractive on the outside.

Most compressor stations are strictly functional, drab industrial looking affairs. are generally built around large, and noisy, reciprocating piston or gas turbine engine installations. The new design was characterized as appearing like a "country church," which completely disguised the quiet electric motor compressor units (Figs. 2 and 3). Further, the emitted noise level from the station was projected to be well below all regulatory noise limits and in the range of existing background levels. On the basis of these plans, the neighbors' objections, and lawsuits, were dropped and permission was granted to proceed with construction.

After the compressor station was built and operating, a field noise survey was conducted to determine its acoustic performance. Measured noise levels were below the levels projected for this installation. At a neighboring residence the station was inaudible. During the noise survey the resident emerged from the house to investigate. She asked, "When are you going to turn that thing on?" Upon learning that the station had been running for over two months she replied, "Really? I thought it was going to shake the ground!" The very strict noise requirements for this project were met by using quiet, European-built equipment.

C. Active noise control in flight

A growing segment of the airline industry is the market served by regional, or commuter, turboprop aircraft. These flights generally carry about two dozen passengers between large city airport hubs and destinations in smaller cities several hundred miles away. The distances covered, and the passenger traffic volumes, do not justify the use of larger jet aircraft.

One of the complaints voiced most often by passengers about a commuter flight is the noise level in the aircraft cabin. The cabin interior noise is characterized by a loud, low frequency drone. This is largely the result of sound emitted from the rotating propellers impinging on the aircraft fuselage walls. American and European manufacturers have attempted for years to solve this cabin noise problem, with limited success.

Aircraft interior noise arises in part from the complex interactions of the airborne noise from the propeller and engine with the aircraft fuselage structure. Also, engine and propeller vibrations are carried as structure-borne noise into the cabin. A technology which offers great promise toward a solution of this daunting problem is active noise control. A system of microphones and loudspeakers installed in the cabin, with electronic controls that apply active cancellation algorithms, can be optimized to reduce interior noise levels. This type of system is well suited to the small spaces and low frequency noise inherent in turboprop interiors.

Only one manufacturer produces an aircraft model with an active noise control system that is presently in commercial flight service. The Swedish aircraft producer, Saab, has teamed with an English firm, Ultra Electronics, to install cabin noise control systems on the Saab 340 turboprop airplane. This system is somewhat effective in reducing interior noise levels, and therefore, contributes toward the increased comfort and satisfaction of passengers. No American builder currently offers a similar system. This is likely to become an important factor in the competition for future sales of commuter aircraft.

D. Consumer goods

People who purchase consumer goods have shown a rising interest in the noise that these products generate. The level and character of noise are becoming important factors when the public discriminates between competing models. This interest has been given a fair amount of attention in the general press. 10-15

Consumer goods that generate significant noise levels include such products as household appliances, lawn and garden equipment, and hand and shop power tools. In the area of consumer goods, the customer's perception of noise from a given product is perhaps more important than any objective measure of emitted noise levels. This is certainly rue in the U.S., where there are no mandated noise standards for consumer products.

In Europe, there exist "old approach" Directives which apply to some products.5 Of these products, only lawn mowers are subject to a type approval with a noise level limit. Household appliances do not need type approval for noise, but voluntary measurements may be made for labeling purposes. For both of these classes of products, the manufacturers or importers may perform the noise test for certification.

Clearly, in the arena of consumer goods, the marketplace is a stronger determinant than any govemment mandate of the noise that a given product is allowed to emit. Customers have been performing subjective ratings of consumer goods with regard to noise for as long as there have been such products. Yet, little quantified noise data are readily available. For example, the Consumer's Union, a generally thorough product testing organization, reports only subjective relative "quality" ratings for noise, ranging from poor to excellent.13 For a recent survey of vacuum cleaners, these tests are described as follows, "Even the least raucous cleaner makes plenty of noise. These models ranged from a slightly annoying hum to whines, whistles, and rattles loud enough to drown out conversation."

The subjective response to a product's noise is an important gauge of that product's potential for success in the marketplace. In the effort to develop a means to quantify the public's perceptions a new discipline known as "Sound Quality" has emerged.16 The methods of a sound quality investigation include the sophisticated polling of a panel of consumers, who listen to samples of the noise produced by various product models, to determine their perception of the relative quality of each model. 12,14

Manufacturers may ignore the public perception of a product's noise at their peril. Further, a manufacturer must understand that the consumers in various market areas may have different preferences. Good examples of this include household laundry appliances.

Several U.S. manufacturers recently failed to compete successfully in the European appliance market by misjudging European consumers. 15 They applied an American market strategy of offering the lowest possible price, believing that people will simply throw away the machine when it wears out. However, Europeans often view appliances as long term investments, and are willing to pay for a better product. This dichotomy was described as follows, "An American household will often put its washer/dryer in the garage or basement where noise and appearance don't matter, but Europeans live in smaller houses and often put their laundry equipment in their kitchens, where noise and looks matter greatly." Clearly, EU appliance makers were better prepared to meet the demands of the European market.

Current market research shows that the trend toward placing laundry appliances near the kitchen, with the need for lower noise products, is gaining in the U.S.16 Also, the familiar kitchen noisemaker, the dishwasher, is getting more attention. Until recently, the only truly quiet dishwashers available were expensive European models.

Measured noise data from 1974 and 1994 show that just a moderate reduction in noise level was achieved by one U.S. manufacturer of dishwashers for its top model over a period of 20 years (Fig. 4). However, within the past year several manufacturers have introduced low noise dishwasher models. As one appliance executive states, "For many years, the focus has been on making dishwashers that clean better. Now, consumers assume they all clean reasonably well, and what has become a very important factor to the high end is quiet." 10 Again, European manufacturers have a head start over their U.S. counterparts. They have a better understanding of the needs of the market and more experience in building products that satisfy those needs.

Similar findings were recently made conceming Asian markets for home appliances.17 Noise is always an important consideration in a purchase decision and Asian manufacturers recognize this. U.S. manufacturers must pay more attention to noise in order to compete successfully in that market. A U.S. company official is quoted as stating, "If we don't produce a quieter product, we shall neither be in the Asian market nor even remain in business."

6. NOISE CONTROL MARKETPLACE - A VISION

The lessons of competitive markets are clear. Product sales are driven by customer needs and desires. Low noise products are sometimes needed, but almost always desired. As an important factor in the marketplace, low noise provides an opportunity for competitive advantage.

What has emerged from the observations discussed above is the vision of a noise control marketplace. This vision recognizes that global business demands that every advantage be taken to develop quieter industrial machines and consumer products. It is also seen that noise standards exert influence on markets, both directly and indirectly. For example, foreign regulations do not necessarily mandate low noise products for the U-S- market, but they raise the price of entry into the worldwide market.

In order to sell to industry in Europe, a product must have the "CE&" marking. There is currently no equivalent requirement in the U.S. However, low noise is increasingly becoming a demand of the product buyer, regardless of govemment intervention. In this atmosphere, European manufacturers already have much experience producing low noise products. Their U.S. competitors are lagging behind.

7. RECOMMENDED ACTIONS

A concerted effort on the part of U.S. industry is needed to respond to the challenge of a competitive noise control marketplace. As in many aspects of life, recognition of a problem is the first step toward a solution. Therefore, it is vitally important to promote awareness of noise issues among industry decision makers. Once these key individuals know the competitive value of noise control in their markets, they can begin to assign resources to the development of quieter products.

Many companies, however, do not have the means to undertake low noise product development efforts completely on their own. Nor is it necessary that they act alone. Industry can benefit in this endeavor from the help and expertise of professional organizations with an interest in noise and its control.

Over the past several years, the Technical Committee on Noise of the Acoustical Society of America (ASA) has sponsored a series of events with the goal of defining the role that the society should take in noise and its control for a wide range of issues. These events occurred at society meetings and included a panel discussion session, a workshop with over 40 participants to define issues and actions,and continuing progress report sessions to discuss the development of the recommended actions. 18

The focus of these discussions was on actions that would be appropriate for the ASA to take, recognizing that it is primarily a scientific organization with a charter duty to disseminate information. However, many of the recommended actions that were identified are those in which other professional societies could, and indeed should, participate. Many of these actions, to be successful would require collaboration between the ASA and the Institute of Noise Control Engineering (INCE), as well as other engineering societies with noise concerns, such as the Society of Automotive Engineers (SAE), the American Society of Mechanical Engineers (ASME) and the American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE).

As each of these organizations consists largely of individual memberships, energetic action is necessary to reach these recommended goals. Therefore, participation by all interested parties is strongly encouraged.

The recommended actions to be taken by the noise control community are grouped into broad categories. They include:

A. Industry awareness of noise issues

The first task is to promote industry awareness of the benefits of noise control. Information about noise issues may be disseminated through many avenues. Noise control engineers, and other noise control advocates are urged to:

. Contribute to industry publications, such as design guides, articles and columns in the trade press. There are many publications suitable for this effort.

. Encourage voluntary sound quality ratings by trade groups.

. Develop and present talks to trade groups.

. Conduct special sessions at society meetings on industrial noise concerns.

B. Standards

Many people in industry feel strongly that an area needing more attention is field of standards. Too often, the people responsible for applying quantitative standards during the engineering development of their products do notparticipate in the formulation of those standards. The organizations that publish noise standards must make every effort to:

. Insure industry representation for consensus standards.

. Educate professionals outside of ASA, INCE, and the noise divisions of related societies on noise ratings, noise standards and noise legislation.

C. Coordination

A key to the success of any group effort is good communication among the participants. It is essential that organizations with an interest in promoting noise control maintain open contacts to discuss ideas and coordinate their activities.

This communication has already begun with the creation of an informal Coordinating Group on Noise Control Engineering which has met several times in conjunction with ASA and INCE general meetings to discuss a broad array of issues. Individuals have attended representing a wide variety of organizations, from industry and academia to government, who are active in many different engineering societies. Additionally, further outreach is needed beyond the noise control community to:

. Establish liaisons with manufacturing and industrial trade organizations as well as with consumer organizations.

D. Information clearinghouse

There is an identified need for a central repository of information useful to manufacturers, consumers or anyone else interested in noise control. It could include:

. Basic information on noise and its control

. Documentation on noise assessment, measurement, mitigation and management.

. Database on the feasibility and costs of engineering noise controls.

. Database on the noise ratings of "CE" and U.S. market products.

E. Government activity

In this era of reduced action, govemment can still play a vital role assisting U.S. industry to compete successfully in global markets. Many believe that the considerable resources of the federal govemment can, and should, be focused on this issue. This is particularly needed for the noise control marketplace. Instead of a relationship based strictly on regulation, which may at times be adversarial, industry and govemment must recognize their common goals and form a new alliance based on mutual cooperation and encouragement. Govemment officials should take the initiative to:

. Define a new role for the EPA and other agencies, in partnership with industry.

. Develop economic incentives for manufacturers to include product noise control in their research and development activity.

8. Conclusions

The global noise control marketplace is here. It is essential that U.S. industry recognize that fact, and then move rapidly to meet the challenge. If viewed as an opportunity, product noise control will help business to not only survive, but to thrive. Everyone with an interest in noise and its control needs to play an enthusiastic role in this program. Some of the recommended actions are already being implemented, but only through wide participation will further progress be made. A small effort by many will help to assure a successful future for all in the global marketplace.

9. References

¹F. A. White, Our Acoustic Environment, Chapter 12, Legal Aspects of Noise Abatement (Wiley, New York, 1975).

² C. M. Harris, Handbook of Acoustical Measurements and Noise Control, Chapter 50, Noise and the Law (McGraw-Hill, New York, 19941.

³L. L. Beranek and I. L. Ver, Noise and Vibration Control Engineering, Chapter 16, Damage Risk Criteria for Hearing and Human Body Vibration, and Chapter 17, Criteria for Noise and Vibration in Communities, Buildings, and Vehicles (Wiley, New York, 1992).

⁴L. H. Royster, M. Peeler, and J. D. Royster, "Additional information on OSHA Noise Citations from 1988 to 1992," Spectrum 10(4), 22-23, (1993).

⁵R. F. Higginson, J. Jacques, and W. W. Lang, "Directives, Standards and European Noise Requirements," Noise News Intl. 2(3), 156-184 (September 1994).

⁶S. Gade and E. C. Peterson, "An Introduction to Product Noise Directives in the European Union," Sound Vib. 29(11), 18-21 (November, 1995).

⁷ I-INCE Publication 94-1, "Technical Assessment of Upper Limits on Noise in the Workplace," Noise/News Intl. 2(4), 227-237 (1994).

⁸D. Gottlob, "Regulations for Community Noise,'' Noise News Intl. 3 (4), 223-236 (December 1995).

⁹U. Sandberg, "Report by the International Institute of Noise Control Engineering Working Party on the Effect of Regulations on Road Vehicle Noise," Noise News Intl. 3(2), 85- Ii 3 (June 1995).

¹⁰K. Blumenthal, "A Maxim for Home Builders: These Days, Silence Is Golden,'' Wall Street Journal (2 February 1996).

¹¹J. Bigness, "Scientists Study Secrets of a Quiet Office,'' Wall Street Journal (21 August 1995).

¹²J. E. Bishop, "Why Vacuum Cleaners Are Louder and Other Acoustic Mysteries,'' Wall Street Joumal (30 August 1994).

¹³"Vacuum cleaners ratings and recommendations," Consumer Reports 61(3), 27-35 (March 1996).

¹⁴R. Wolkimir, ''Decibel by decibel, reducing the din to a very dull roar,'' Smithsonian Magazine 26( II ), 56-65 (February 1996).

¹⁵M. Berss, "Whirlpool's bloody nose,'' Forbes Magazine 157(5), 90-92 (11 March 1996).

¹⁶R. H. Lyon, "Selling, designing and producing products that sound good," Proc. lsth, ICA, edited by Mike Newman, Vol. III, 189-194 (TAPIR, Trondheim, Norway, 1995).

¹⁷R. Cann, "S&V News - Quiet Products in Asia,'' Sound Vib. 30(3), 2 (March 1996).

¹⁸B. M. Brooks, T. J. DuBois, R. M. Hoover, G. C. Mating, and L. C. Sutherland, "The role of the Acoustical Society in noise and its control,'' J. Acoust. Sac. Am. 98(1), 18-19 (1995).

10. Authors (back to top)

a) Brooks Acoustics Corporation, 27 Hartford Turnpike, Vernon, CT 06066, USA.

b) DuBois andAssociates, Tujunga, CA 91042, USA.

c) Hoover and Keith, inc., Houston, TK 77082, USA.

d) INCE/USA, Poughkeepsie, NY J2603, USA.

e) Consultant in Acoustics, Rancho Palos Verdes, CA 90275, USA.