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Potential for Control

Broadway director and drama critic Harold Clurman and I were walking along one of Manhattan’s lovelier streets one balmy spring day. A truck barreled by. He winced, and we had to stop conversing. As we progressed, a jackhammer suddenly opened up at a street repair site. He winced again, much disturbed by these noises, but he failed to make any comment.

“Doesn’t this noise upset you?” I asked, when I could.

“Upset me! That’s putting it mildly. Have you ever tried to direct a show with heavy truck traffic outside the rehearsal hall, not to mention the sirens and the horns? Can you imagine putting together a play review while living next to a construction site? But what can I do? Noise is one of the curses of civilization.”

“Would you believe trucks could be designed with less noise, and that jackhammers are made with built-in mufflers?”

“Stop pulling my leg,” he replied. “You’ve been reading too much science fiction.”

Noisy equipment is a sign of imperfect design. At the same time that man’s inventiveness has enabled him to produce the noisiest epoch in his history, it has also given him tools for eliminating or minimizing all that noise. So refined is the application of these tools, noise control experts have designed a systems approach to any given noise problem. Its formula is “source/transmission-path/receiver.”

Translated into action, this formula means that to solve a noise problem the first step is to find a way to eliminate noise at its source. If not, block the sound waves after they are generated. Or, finally, find a way to separate the receiver’s ear and the acoustic energy.

The science and technology of noise control are quite sophisticated. Equipment can be designed to meet goals for preventing hearing loss, for permitting speech communication, for minimizing “annoyance.” The design engineer has available a limited number of guidelines ranging from voluntary codes adopted by an entire industry to purchase specifications and–rarely–legislation.

Some guidelines set limits for the allowable noise to be emitted by a given machine, others, for the amount of noise allowed at the receiver’s ears. Most available guidelines or standards specify what instruments are to be used to measure the noise, and how these measurements are to be taken. The basic measuring instrument is the sound level meter. This device–which comes in all sizes, including portable, hand-held models–makes possible the comparison of various sound intensities ranging from the decibel reading in a bedroom at night to the sound intensity of a passing truck or jet. Sound level meters are in use throughout the world. One manufacturer prints instruction sheets in sixteen languages, including French, Russian, Norwegian, German, Finnish, Japanese, and Chinese.

There are also instruments for analyzing the decibel level of sounds at various frequencies. With these analyzers it is possible to tell how much of the sound energy is in the low pitch, middle pitch, or high pitch range. They can analyze the acoustic energy in hisses, swishes, sizzles, rattles, and buzzes, and can be used for the rating of product noises, the measurement of noises proscribed by local ordinances, and the designing of auditoria.

It should be noted that though they are commonly referred to as noise meters, the sound level meter and the analyzer are, more correctly, means of measuring the two physical qualities of sound–intensity and frequency; they do not measure human response to noise.

For acoustical research and design applications, technology has provided an incredible array of more sophisticated measuring and analyzing instruments based on decibel measurements. There are impact analyzers, to measure impulsive noises too brief to give a reading on the dial of the regular sound level meter. There are oscilloscopes, by means of which sound can be observed and measured visually. There are tape machines that can record noise on location for subsequent analysis in acoustic laboratories. As you listen to your noisy appliances, think of the noise level meter available for factory production lines to assess the noise and vibration output of each item.

The most effective and possibly the least expensive method of noise abatement (as far as society is concerned) is to design machines that generate and radiate little noise. Engineers can be trained to determine if a given noise can be reduced at its source. Machine noise is not “natural.” According to one consulting engineer, “Noise is a form of pollution that is not necessarily inherent in the design of larger, more powerful systems and equipment. It is not necessary for design engineers to accept increased noise and vibration as an unavoidable accompaniment to the power, capacity, and efficiency of industrial machinery.”

Given the motivation, engineers can select silent operating levels, can specify low tolerances for moving surfaces, can call for the use of bearings with relatively few imperfections. (It is said that bearings of the future will be made in outer space, with the result that each bearing will come out perfect.) Gears can be designed to make less noise, and in some cases they can be fabricated of nylon or other plastic instead of noisier metal.

Engineers can check thin metal housings for vibration, and rotating machinery for imbalance. They can select a type of metal that will not vibrate as readily as another.

With or without guidelines, the motivated engineer can measure the decibels as a diagnostic means of tracing machine parts that are responsible for unwanted or unnecessary sound. For example, in precision design, an air conditioner or lawn mower could be isolated in an anechoic room–a room so quiet that one begins to hear the internal sounds of his own body–in order to determine the total sound power level. The design engineer can isolate tones, obtaining a picture of how the noise energy is distributed, from rumble to high squeal. Moving parts making unwanted sounds can be identified.

One of the most dramatic examples of effective silencing–the car muffler–was developed before there was a science and technology of decibels, even before the invention of the sound level meter. The automobile industry had to develop effective muffling to keep from frightening horses on the roads. Unfortunately, we do not insist that new noise-suppression methods be developed to keep from frightening humans.

Noisy machines can be partially or completely enclosed in barriers. At Baden-Baden a dramatic reduction of noise was achieved by placing what looked like an open-ended privy around a jackhammer and an air compressor. The open end, which faced away from the public, provided light and ventilation, while sound-absorbent lining made life a little more bearable for the operator.

In this country, partial or full enclosures are employed in factories to protect machine operators from noise produced by very noisy automatic screw machines and jolt-squeeze hammers. (Similar enclosures are available for electric typewriters and calculating machines.) Several companies make standardized soundproof panels that are fitted together to shield noise-sensitive areas in factories. This principle could be adapted to enclose suburban electrical generating stations, noisy turbine generators, and other sources of noxious noise.

It is possible to stop the transmission of noise through attached structures by breaking the acoustic path through walls and floors. With vibration isolators, springs, pads, or rubber mounts in use, apartment dwellers need not suffer from noises radiated from elevator or central air conditioning operations. Ford, Bethlehem Steel, and other industrial giants reduce the noise of operating equipment to safe levels by placing shock and vibration mounts under machines.

Window air conditioners operate less noisily if properly mounted: that is, isolated from the window structure. Resilient gasketing keeps the vibrations of rotating parts from being transmitted to the windows, and into the walls, floors, and ceilings. Even the tiny motors used to aerate fish tanks can create quite a hum. If placed on a foam rubber or other resilient base, however, their noise-making is reduced.

Most of the literature of noise control quickly glosses over the most fundamental approach: source substitution. Noisy equipment and processes can be replaced with quieter substitutes. Bolting and welding are quieter ways of putting up a building than riveting. The banging of punch presses can be eliminated by substituting hydraulic pressure to shape the metal.

Electric motors can be substituted for noisy internal combustion engines. Electric vehicles, in use in England, not only make but little noise, they have no exhaust fumes. Small electric lorries, tested at normal town speeds, were much quieter at a distance of 7 meters than diesel and gasoline counterparts:

diesel	81 dB(A)
petrol	80 dB(A)
electric	60 dB(A)

Diesel and gasoline vehicles are even noisier when shifting gears or accelerating.

Another quieter substitute for the internal combustion engine is the gas turbine engine, and turbine-operated buses are undergoing operating tests. Air compressors operated by propane gas engines are strikingly quiet. Fuel cells and steam engines provide quiet power without air pollution.

Other examples of quiet by means of substitution are the use of plastic or paper sacks instead of metal garbage cans, nylon rollers instead of metal. The list of quiet substitutes for dangers and bangers is quite long.

Being a practical people, we want to know how much it will cost to make things that will operate with less noise. Though the impression has been created that quieter design and excessive costs go hand in hand, there is no universal law that says this is so. A metal garbage can without clang might cost $1.50 more than standard cans, but given volume and improved design the price differential would become meaningless. The quieter, less polluting chassis for the first 400 garbage trucks ordered by the City of New York cost less than $100 extra. The ten dramatically quiet garbage trucks subsequently ordered by New York cost $17,000 each, as against $15,000 for the noisy models. But these are experimental units, and should go down in price as they are produced in volume.

An 85-pound silenced jackhammer imported into the United States for public demonstration by CQC cost $175 less than its unmuffled American counterpart. Comparing unmuffled and muffled imports showed an increase of but $60, or 11.6 per cent. The first large-size (900 cfm) silenced air compressor cost 25 per cent more, but this increase of $9,300 must be placed in perspective: a portable air compressor may operate for five years before requiring extensive repairs. The projects on which these machines are used may cost in the millions of dollars. Any marginal addition to the cost for silencing is not significant.

As for appliances, engineering professor Howard Kingsbury smeared all panel surfaces of an automatic washer and under-counter dishwasher with a fibered automotive undercoat and glued to this a glass fiber blanket. Resilient pads were placed around the dishwasher to separate it from the floor and counter structure. The result was a much quieter appliance; the isolating cost pennies on a do-it-yourself basis, and if done commercially by the manufacturer it might add not more than between $2 and $5 to the cost.

The Federal Council for Science and Technology supports the conclusion implicit in Professor Kingsbury’s experience: “It is possible that quiet devices and appliances could be built at the same and perhaps even less cost than their noisy counterparts by the use of appropriate design.”

Quieter dishwashers and other appliances, because of improved design and less vibration, last longer and require less maintenance expense. Quieter appliances built into dwellings add little to construction costs. A quiet siphon-jet toilet may cost only $5 more than an ordinary noisy one. Canvas connecting sleeves to prevent furnace rattle and rumble from being transmitted through the house via the ductwork may add but $12. Noiseless nylon rollers in the overhead garage doors may cost only $5 more than the noisy metal ones.

Adequate statistics on the cost of sound-conditioning dwellings are not readily available. One reads of additional costs ranging from 2 percent to 10 percent. Care must be taken to ask, per cent of what? The basic construction cost? Or, the much greater total cost which includes financing and other non-construction costs?

Some builders and the FHA regard improved design as a plus factor. Referring to the problems of noisy dwellings, the magazine Buildings stated: “Fortunately there are solutions which can be obtained with a small investment in vibration and noise control and which will result in a high degree of occupancy and tenant satisfaction.”

The FHA reports that noise control, if considered early in the planning stages, not only can be surprisingly inexpensive, but can be designed to yield other benefits as well, such as thermal insulation.

Speaking of costs, never a peep is heard about the astronomical costs of noise control in defense and space projects. Who tells the Department of Defense that its noise control programs are too costly, or that the noise that makes a submarine audible to the enemy is the price of progress?

The tyranny of noise could be ended if society asked that noise emissions be reduced and that structures be noise-insulated. The armed services and the defense-related space program ask, and receive, such noise control from the manufacturers of materials they use. Budget priorities have made it possible for man to know more about noise in space, in space capsules, and under the seas than he does about noise in his cities.

With the almighty power of the contract, the military have called upon industry to subdue the most awesome of noise sources, and to perform prodigious feats of combining power and propulsion with quiet. These non-public sectors also build themselves offices and living quarters that are oases of quiet in the midst of jet whine and rocket blast associated with the space program and military bases.

Though the first municipal office of noise control, New York City’s, was not announced until 1969, the Air Research and Development Command recognized the growing requirement for research data on noise and its control as early as 1952. In that year it created the Office of Coordinator of Noise and Vibration Control. In 1954, faced with many complaints from communities near air bases, the Air Force sponsored the first major Federal government study on community reaction to noise. (Unfortunately for the public, this and subsequent studies revealed that community responses to aircraft noise “are influenced by many variables.”)

Since 1953 the Air Force has been designing installations in and around air bases to meet noise-control criteria. In 1957, these criteria were improved and published for the guidance of base commanders. In 1954 the Air Force initiated a program to study missile noise, its generation, propagation, effects, and control.

To cope with noise problems in outer space and in the skies, the Air Force in 1957 opened a $1.3 million Bioacoustics Research Facility for studying the effects of high-intensity noise on man. This facility has specialized noise exposure rooms, audiometric rooms, medical observation rooms. It is the only laboratory of its type in the country, if not in the world. When first opened, it was staffed with thirty scientists and engineers. Ten years later–at a cost of $12.4 million–the Air Force opened its Sonic Fatigue Facility to investigate the effects of noise on materials. This facility was staffed with fifty scientists and engineers.

By 1960 Congress could be told that the Air Force was attacking the noise problem with a systems approach, “to insure control of human exposure to acoustic energy and vibration, to assure levels of acoustic energy that would be acceptable to humans in a normal working or living environment, to prevent damage to structures by controlling acoustic energy levels, and to provide or develop general noise criteria for aircraft and missiles upon which to base airbase and missile site planning.”

The U.S. Navy has had a shipboard noise problem for many years, most particularly on aircraft carriers. In 1952 the Navy’s Bureau of Medicine and Surgery started its first significant research approach when it measured the noise levels on the flight deck. Noise intensities frequently reached more than 130 decibels. As a result of this research the Navy contracted with the Psychoacoustic Laboratory at Harvard University for additional noise studies. During 1954 and 1955 great strides were made in the development of earplugs and other ear protection devices. In 1960 the Navy issued contracts to two industrial concerns for research and development of an advanced-type portable ground suppressor that muffled the noises generated by the jet engine and its exhaust.

Most of the Navy’s current research has gone underseas, where it is expected some of the key battles of the future will be fought. While few cities have as much as a sound level meter, the Navy’s acoustic research facilities range from two-man submarines to the 354-foot SPAR (Seagoing Platform for Acoustics Research). SPAR is used to study underwater sound transmission and propagation, and can make highly precise noise measurements at depths of 300 feet. This is all the more interesting because on dry land, civilian noise experts cannot agree on a practical, enforceable method of accurately measuring highway motor vehicle noise at 50 feet!

There have been no noise-abatement developments in civilian hardware comparable in sophistication–or cost–with the new breed of submarines that silently ply the seas. These technological marvels run by powerful motors are ventilated and cooled by motor-driven devices; they contain generators, compressor, fans–in short, almost every type of mechanical and electrical noise source. But if they operate noisily their price of progress will be death. To elude detection by the electronic ears of an enemy, these subs’ diesel engines are enclosed in acoustic enclosures; their special engines are designed to meet “tuned” frequencies–that is, not to exceed more than the prescribed number of decibels in each of specified octave bands.

With the help of a $150 million authorization from Congress, the Navy works on an improved “quiet” submarine, which they hope will be 30 per cent quieter than the current model. Elaborate design changes include the substitution of electric-driven propulsion for current diesel systems. A slow speed of 25 knots will further reduce noise emissions, and bearings, an important source of noise, will be given special attention.

The U.S. Army has been conducting a variety of researches, including developing a quiet airplane. Military editor Hanson Baldwin reported in The New York Times (October 17, 1967): “The Army of tomorrow will reconnoiter the battlefield with silent aircraft…The study of silent planes to replace noisy helicopters for surveillance behind enemy lines or over battlefields includes tests of a new Lockheed QT-2…[that] flies so quietly…it is difficult to hear. Modified versions of the Grumman OV-1 Army observation plane are also being tested.”

Once preoccupied with aviation noise, NASA by 1960 had reoriented its noise research towards investigating the noise problem of manned space flight and sonic boom. During space launchings, astronauts must be, and are, shielded from noise intensities of more than 175 decibels, and from accompanying low-frequency energy that could cause harmful vibrations within their bodies.

Even attack missiles are protected. When it was discovered that the intense noise generated by the launching of ICBMs from concrete underground silos was damaging the “skin” of the missile and its delicate instruments, a method was found to reduce exposure by lining the silos with sound-absorbent material.

Civil Defense demands and gets more acoustic expertise than peacetime functions. When the Civil Defense people wanted to know how well sound in the form of sirens and the spoken word traveled down city streets, money was found for a thorough study under private contract. How much money does your community have for measuring fire engine sirens and outdoor speech communication?

Not until 1963 did the Public Health Service publish a detailed analysis of hospital noise and its control, covering all potential noise sources from site selection to bedpans. An analogous guide was published three years earlier by the British Standards Institution.

Noise control is no secret to hotel and motel operators. In 1955 a University of Michigan professor compiled a detailed program of motel sound control. Owners were told to try to avoid noisy sites, to angle buildings and set them back from highways, and to try to flank them with other buildings.

It was also pointed out that management could protect guests by controlling certain outdoor operations: noisy power mowers should not be run during hours of sleep, and room cleaning should not be scheduled for too early in the morning. Even seemingly small touches were suggested: using wooden wall racks on sound-resistant walls (instead of metal hangers on resonant doors), sound-deadening metal rods by wrapping them with tape or a plastic covering, adjusting phone bells or buzzers to limit the sound, and installing silent door closers and volume controls in radio and TV sets. It was even suggested that windows be checked for rattle.

To obtain and disseminate its noise control know-how, private industry sponsors factory noise control research, industrial noise symposia, and hearing-conservation programs. It supports the work of professional societies responsible for developing standards. On its payrolls are acoustical engineers and medical specialists in industrial hearing loss.

Enlightened management knows the danger signs for hearing loss and accidents: if conversation at arm’s length is impossible in the plant; if warning signals are inaudible; if telephone use is made difficult because of noise. Design goals for factory machinery are usually concerned with reducing the noise level to as close as possible to 85 decibels in the critical speech frequencies (500, 1,000, and 2,000 cps.). Given the noise emission of a particular machine or process, management can take steps to regulate the amount of time the worker is exposed to dangerous noise, or urge him to use ear protectors.

Bethlehem Steel, DuPont, Western Electric, and Ford are among the big companies that undertake internal noise control and hearing-conservation programs. General Motors’ new foundry at Defiance, Ohio, was designed to incorporate current concepts in noise control. The interior of all outside walls is covered with acoustical paneling four inches thick. Individual high-noise-level operations inside the buildings are housed in sound-barrier construction.

Industrial hearing-conservation programs include an analysis of noise exposure and the measurement of the employees’ hearing acuity. An ideal plant hearing conservation committee is comprised of the plant manager, the company physician, the industrial relations manager, labor relations supervisor, workmen’s compensation representative, plant engineer, and manufacturing engineer.

Noise-conscious industry does not expect that it will be able to buy every noise-control product it needs “off the shelf.” Many noise controls must be engineered within the plant or especially designed by vendors.

Not only is some industry willing to custom-build when necessary, it is willing to experiment. It recognizes that the consideration of noise in design is, as Jim Botsford puts it, “in its infancy–there are few established guidelines to follow. Each noise problem is unique. Many noise problems can be solved from an evaluation of the environment, by proper use of available criteria or guidelines, and by use of available information on noise control. The job does not end with the design of the noise control measures. Their performance must be checked after installation and modifications made if needed because noise control in industry is still based partially on trial and error.”

What a contrast to the attitude of local bureaucrats who turn a deaf ear to pleas for noise control, on the grounds that the equipment to implement it is not readily available on the market, and do not seem to be imaginative enough to think in terms of having the needed equipment devised.

Nothing representing industrial awareness and use of noise control permeates the public sector of American life. Why should it? Industry expects a payoff in fewer claims for hearing loss and accidents, more productivity, and public acceptance of the plant’s presence and activities. Its noise control program is further testimony to a double standard: noise control for the private (and military) sector, and just plain noise for the public. Yet with motivation, the builder or maker of things could provide convenience and speed to the public, without the excessive noise.

Though Europeans are subjected to many of the same disturbing noises of commerce and traffic that affect Americans, there is a basic difference: an attitude that men should be protected from excessive noise. Consequently, many Europeans benefit from advances in everyday noise control.

Many responsible citizens in Europe have organized against noise. National organizations belong to the International Association Against Noise, or AICB. Incorporated as an international organization since 1959, AICB convenes a congress on noise abatement every two years, providing a much-needed forum for the exchange of information.

Many areas of government, on national and local levels, show responsiveness to the noise problem. There is more of a commitment to abate, as evidenced by the laws, personnel to enforce the laws, and acoustic laboratories to back up enforcement and pave the way for improvements.

Zurich (population 600,000) has two agencies for noise control: public health, and the police. A half-day spent with the Zurich noise control police in 1966 was quite a revelation, after experiencing the abysmal ignorance and indifference of New York City’s government.

The Zurich Police Office of Noise Control consists of a sharedtime commissioner and four fulltime sergeants. Each sergeant is required to have ten years of experience as a patrolman, plus one year of noise abatement study at the hochschulle. He must keep up to date on noise abatement developments. Facilities include an assortment of decibel-measuring instruments. One room of the office contains an exhibit of noise-control products, including jackhammer mufflers and building materials that keep out sound. This “library” is visited by noisemakers who want to employ noise abatement methods, and by anti-noise law violators.

An American policeman, hearing a motor vehicle with an obviously noisy muffler, can issue a summons. However, if the operator chooses to plead not guilty, the policeman must spend a day in court and satisfy the judge that the vehicle in question was creating “unreasonably loud” noises. This time-consuming and subjective enforcement procedure discourages strict enforcement.

Contrast this cumbersome and lengthy procedure with that in Switzerland (or Germany) where if a policeman issues a citation for a noisy vehicle, the operator (or owner) is required to take the vehicle to a testing station immediately, and cannot drive it again until it is certified as suitably quiet. In Zurich, the police keep the operator’s license until the repairs are completed.

The German Federal government has been able to regulate traffic noise for decades because decibel standards have been set for the whole spectrum of motor vehicles, including motor bikes. An operator’s license is issued only if there is no violation of these standards. It is also a general philosophy of both German and Swiss motor vehicle laws that the permitted limits will be lowered step by step as technical advances permit.

In addition to muffler control, German and Swiss regulations cover vehicle operations. Drivers must not coast or start out in other than first; unnecessary slamming of car doors, trunks, and hoods is prohibited, as are unnecessary idling and starting of motor bikes in courtyards, gateways, or passages of apartment houses, and slamming of garage doors. In France, automobile radios may be turned on only while the car is moving.

In spite of decibel standards and strict enforcement, traffic noise in Europe remains disturbing. One European acoustic expert, who has been responsible for setting limits, explains: “Yes, our traffic is noisy. We are fighting to maintain a level. Each year there are more vehicles on the road, therefore more noise. We try to lower the permitted levels to at least prevent an increase in the over-all noise generated. Can you imagine what it would be like without any standards?”

It is especially interesting that the Zurich police claim they are stricter than the health department inspectors who, they say, tend to adhere too strictly to decibels. The police depend on an initial human-subjective reaction. Measurements follow, not precede, listening. “A policeman must use his head and his heart to be a good noise policeman,” one of them told me. Amen.

The Swiss government has an acoustic testing facility larger and more complete than any non-military facility in the United States. The Netherlands, population 12,660,000, has a Sound Division in its Research Institute for Public Health Engineering. We do not even have a research facility for public health engineering.

The British government has facilities elaborate enough to develop standards and sound insulation data for dwellings, experiment with soundproofing units for homes near airports, research quieter paving-breakers, and conduct noise surveys.

It was my privilege to be the guest of Dr. R.J. Stephenson, Assistant to the Scientific Advisor for the Greater London Council. He showed me GLC’s acoustic laboratory facilities and mobile noise testing laboratory. This local government lab has researched the acoustic profile of tall buildings, the noise contour of urban motorways, techniques for shielding residential sites from roadways, techniques for soundproofing windows and providing sound-trapped ventilation, scales for evaluating the relationship between different types of windows and aircraft noise intrusion, studies of the impact of helicopter noise on the urban environment. Also investigated was the effect of traffic vibration on historic buildings, particularly when new roads are being planned.

Where can the American public go for similar information? The only way we learn about the impact of traffic noise and vibration and construction blasting is when it cracks a water main and floods the neighborhood.

European health departments, both local and national, are involved with noise abatement. This does not mean they have all of the needed power to curb the serious noisemakers, but they recognize the issue, they press for constructive legislation, they encourage public and professional debate. They have laboratory facilities. In the Netherlands, noise standards for dwellings are developed by a public health engineering facility. Local health authorities in England take an active role in reducing construction noise. They cooperate with the Noise Abatement Society in educational campaigns, in following up noise complaints; they sponsor demonstrations of quieter products; they present experience papers at noise abatement conferences.

In Germany, the Ministry of Health believes both Federal and local governments in all social conscience have a duty to fight intolerable noise situations. It recognizes that legal commands and prohibitions are necessary to restrain human thoughtlessness and negligence. It also recognizes that without laws the development and use of noise control knowledge will remain largely unrealizable.

Under administrative law the German police, too, are involved in noise control. Here is one of their guidelines:

“The police can only pursue complaints about noise if the noise endangers the security or order. A danger to the public security exists when noise endangers health. Whether this is the case can only be determined in each instance. Though noise without harmful effect on health may not endanger security, it can, however, affect public order. That is first of all the case when the peace of night or rest on Sundays and holidays is unnecessarily disturbed; also when it lowers man’s work capacity.”

Although many European cities are noisy, many of them have regulations covering noise sources often not covered by American municipal codes. For example, bicycles with auxiliary motors, which are very popular in Denmark, are also very much of a nuisance. According to the traffic code of the Danish Ministry of Justice, which supervises most driving and traffic regulations, the motors of such bicycles “shall be equipped with an effective device for reducing the sound and it shall be kept in a secure state.” In 1959, special instructions were issued for measuring a specific noise limit (79 decibels at 7 meters), and at the same time a mobile noise control center was established under the jurisdiction of the state police.

Germany and Switzerland protect noise receivers on Sundays and holidays. Special Sunday and holiday laws ban all work performed in public that could disturb the peace. During the main hours of religious services, all possibly disturbing work must cease. In Germany, to reduce traffic noise on Sundays and holidays, there is a statute forbidding trucks (over a certain weight) to drive between the hours of midnight and 10:00 P.M.

Is it possible to produce a quiet jet airplane? Though the ultimate answer is cloaked in ambiguity and controversy, the general impression seems to be that aircraft could be designed to generate tolerable noise levels–at a cost. The ideal would be to start from scratch and develop a form of propulsion in which design for quiet was given as much weight as design for speed, power, and operating efficiency. Some believe this could be done if we made the same financial commitment to developing quiet subsonic aircraft as we are making to develop the SST.

Not only have we failed to make such a commitment, we find every step towards quiet design impeded by dollar signs. A March 1966 report of the Office of Science and Technology concluded that “In general, it is technically possible to suppress the noise of an exhaust jet, however, it is very costly in terms of percent of aircraft gross weight and installed hardware.”

The Federal government has embarked on a jet noise alleviation program involving modifications in air frame and engine design, airport planning, modified flight procedures, and public relations programs. It is not expected that the “quieter engine” will solve the noise problem without moving noise away from the people by means of air traffic procedures, and keeping people away from the noise by zoning to keep residential development at a distance where complaints will be minimal. Sometime in 1972 the FAA in cooperation with NASA hopes to have a quiet engine, some 20 Perceived Noise Decibels quieter than present jet engines. This research engine will provide 50 hours of flight testing. The program is budgeted at $50 million.

In essence, our research goal is for a jet engine quiet enough to reduce the number of vigorous complaints.

To decrease the number of people who will be exposed to jet noise, airports may employ “preferred” runways, runways pointed away from land with dense residential development. Unfortunately, however, uncertain weather conditions and airport congestion tend to interfere with the preferred runway concept. Even if fewer homes, through new airport planning, are noise-impacted, those homeowners who are affected will still suffer.

There have been suggestions for changes in procedure such as slowing planes down, increasing their glide angle, and so forth. Pilots resist these practices on the grounds that they diminish certain safety margins. Indeed, it is stated in the jet-noise report cited above that modifying approach/takeoff procedures can pose safety problems.

With proper planning, new airports and heliports would not be sited where they can destroy livability. America’s planning officials have access to guidelines provided by the FAA to keep from making glaring errors in deciding how far from the airport residential construction and development ought to take place. (An impartial analysis of these guidelines is needed to make sure they provide a desirable environment, and not one acceptable in the terms of the aviation industry.)

Name a vehicle noise source, and it can be tamed. Road reflection from the underside of the motor? Enclose the motor, as did the London Transport Company. Noisy road surface? Use smooth asphalt. Aerodynamic noise? Design the body elements to reduce turbulence.

The automotive industry has at its disposal an incredible array of acoustic expertise. GM alone has about 100 men assigned to its acoustic research section, and headed until his recent retirement by David Apps, an international authority on automotive noise control. The Ford Motor Company has a noise-vibration-harshness research team whose job it is to cope with some 15,000 sound-producing components of a car. The quest is to eliminate some of these sounds, insulate others, and convert the stubborn ones into pleasing sounds for the passenger.

Even the cabs of trucks are being sound-insulated, because drivers and their assistants have been opting for quietness for radio listening and off-duty sleep.

But, let us remember that these noise-control efforts are primarily directed toward driver and passenger comfort, not toward the noise recipients outside the vehicle.

The American Trucking Association claims that methods and techniques for muffling truck exhaust are well known to truck manufacturers and that consequently there is no excuse for offending trucks to be coming off assembly lines.

Manufacturers can do more for quieter trucks than simply installing better mufflers. They can modify the design of air cleaners, fans, fuel injection and air intake systems. Mechanical noises from transmission and chassis could also be designed out.

The chassis GM used for New York City’s garbage trucks was designed with more than a superior exhaust system. The engine itself was quieted by a number of innovations, ranging from a dry-element air cleaner to a five-blade, staggered configuration fan. The fan itself is enclosed in a shroud to reduce noise radiation from the engine housing. To purchasers of these quieter trucks GM recommended the use of tire treads designed to make less noise.

According to the motor vehicle manufacturers, the rubber tire manufacturers are slow to design less noise producing tires. To encourage both quieter tire design and quieter vehicle design, local governments could require lower speed limits for nighttime driving.

Motorcycle noise, in common with that of other motor vehicles, would be severely reduced if the public would ask for proper design, and enforce its demands in the act of purchasing. CQC proved this in December 1967. At a public demonstration the audience recoiled as a motorcycle was started up. The sound level meter read a hefty 110 decibels at 15 feet. The bike was stopped. When it was started up again, the observers heard only an astonishing muted purr: 70 decibels at 15 feet. A 40-decibel reduction. Why the difference?

In the “before” demonstration, the muffler had been removed. To control motorcycle noise a quality muffler is an essential. But so is quiet design. This motorcycle was unique in advertising that it was designed for quiet–and its claim stood up in demonstration.

Though difficult to accomplish in large cities, major arteries can be sited away from residential and other noise-sensitive areas, neighborhood traffic flow reduced by using bypass roads for through traffic, and the noise of stop-and-go driving eliminated by using cloverleafs and Y-interchanges. When all else fails, barriers can be placed between the roadway and the human target.

The Russians, to avoid traffic-noise problems in new towns, set up small models of building blocks representing residential, commercial, and industrial areas. Tests are conducted to see how simulated traffic noise is to be kept from the residential area by using the non-residential buildings as barriers.

Other methods for reducing the amount of noise radiating from the road include depressed road construction, the use of flanking barriers, and covering the surface with plastic materials that absorb tire noise.

Chicago has built “groove ways” or depressed roads for its highway from the Loop to O’Hare Airport. When it is not feasible to depress a roadway, planners can try high shoulders, with landscaping. The Russians are experimenting with barriers on expressways in new city districts. These barriers are earth banks three meters high along each side of the road, terraced down to the buildings and topped with reinforced concrete screens. The topping will be planted with trees.

Architect Morris Ketchum points across the Atlantic to Cumbernauld, a new town in Scotland, where the city and traffic live together in harmony. Its center expressway is depressed and framed by earthen banks. Shopping, offices, and theaters all border this main street. Most of the residential buildings are set at right angles to motorways so that sound cannot reverberate among them. “It is a quiet city.”

Recognizing the difficulty of reducing the daily din of life, towns in Austria, Germany, France, and Switzerland have instituted “quiet zones” in which vehicular traffic is verboten during certain hours of the day and night. An example is France’s Vittell Thermal Spa. In response to many complaints about traffic noise, and to protect the peace of summer vacationists, a Quiet Zone was created within the thermal bath quarters. Traffic of all motor vehicles–including motorcycles–is prohibited between 10:00 P.M. and 7:00 AM. After 10:00 P.M. access to the main part of town, which houses the major hotels, is achieved via roads that lead to large parking zones, which are situated close to the hotels. Newcomers entering the town are informed of the regulations. Enforcement has been no problem.

The ramifications of this “quiet zone” should give the auto industry pause. Here is a case in which society says it will not bother with methods of reducing noise, but will eliminate it by banning the source.

Attempts to curb auto horn blowing began soon after the first horn was blown. The curse of the horn is worldwide, and so are the legislative attempts to lift it.

There are several approaches available today for curbing this irritant. Limits on the intensity and tonal quality can stimulate design of an auto horn that emits pleasing tones, with upper limits set for loudness.

The need for horn blowing can be reduced by substituting an overtaking or passing light system. A special position on the direction-signal switch arm activates head lamps as an effective signal in the daytime. At night, in place of sound signals, the use of such anti-dazzling lights at short intervals is relied on. Austria, for example, minimizes the need to use a horn by requiring that automobiles be equipped with an optical device that flashes intermittently, but without any dazzle. This type of special passing light system is illegal in the United States.

Paris is the pioneer in horn control. Sometime before 1930 the Prefect of Police there made use of horns unlawful after midnight:

Drivers are compelled to slacken the pace of their vehicle everywhere needed, in particular at crossroads, so as to make it useless to use a horn.

Art. 2–Infractions of the provisions of this ordinance will be recorded in orders to pay a fine which will be forwarded to the competent courts.

Drivers learned that they could operate as safely without acoustic warnings as with them, and grew to rely on the auto horn less during the day, also. It was natural that the ban would then be extended (1954) to daytime driving as well.

New York followed Paris in enacting an anti-horn blowing ordinance–one more respected in the breach than in the observance, and one the police seem to enforce in ten-year cycles.

December 18, 1967, was a red-letter day in the American noise abatement movement. The locale was the side of the reflecting pool at that citadel of culture, Lincoln Center for the Performing Arts. The invited guests were important enough–two Congressmen (Theodore Kupferman and William F. Ryan), representatives from the Mayor’s office and his task force on noise control, representatives of American manufacturers of pneumatic construction equipment, and members of the press. The star of the occasion was a yellow two-wheeled contraption imported from England, something never before publicly demonstrated in the United States, and not being manufactured here: a silenced portable air compressor. Thanks to the English business contacts of Anthony Essex Potter, CQC Board Member, and a British construction equipment manufacturer, Holman Bros., CQC was able to inform the American public that unmuffled construction noise was not necessary.

Several months later, Ingersoll-Rand announced a quieter American two-wheeled compressor, and then topped this with the marketing of a silenced giant four-wheeled compressor (900 cfm) that generated 85 decibels at 1 meter, instead of 105 decibels. Thus was started a gradual move to introduce a degree of quiet design into pneumatic construction equipment. It is taking more than five years of my life, but the days of raw, uncontrolled construction noise are numbered. In April 1970, I was informed by Joy Manufacturing Company that it was introducing a complete line of quieter compressors, ranging from 175 cfm to 1,200 cfm. The design goal was 85 decibels at 1 meter for a premium of 25 per cent, and 90 decibels at 1 meter for an increase in cost of 10 per cent. Electric air compressors, heretofore kept under wraps by their manufacturers, are now being used for tunnel projects, and for public works sites where militant residents insist on quieter operations. The first electric compressor I experienced was in 1966 in Zurich. Serving a major street renovation project, it was, compared to the monsters on Sixth Avenue, almost a joy to hear. And no dense diesel fumes on-site.

At that same Lincoln Center demonstration, co-star billing was given to two jackhammers with built-in mufflers, one imported from Holman Bros. and the other discovered in the catalogue of Chicago Pneumatic Tool Co. Both were some hefty 10 decibels less than their noisy unmuffled competitors.

There is nothing impractical about jackhammers with built-in mufflers. The principles governing Holman’s design improvement are: 1) the performance of the machine cannot be noticeably reduced, 2) its bulk or weight cannot be increased to the point where it becomes difficult to handle, and 3) the additional cost is to be moderate.

Today other American companies are making quieter jackhammers, and one puts out an accessory muffler that fits around the shaft of any regular jackhammer. Electric hammers are available and eliminate the punch of the pneumatic exhaust. The French are marketing, in the United States, hydraulic paving-breakers with a patented treatment of the internal piston that reduces much of the noise from that source. They combine the breaker with a small silenced compressor as a special package for utility company night work. Hughes Tool Company markets a rotary “cookie cutter” that quietly cuts circular holes in pavement. The primitive mechanical pile driver, with its day-long pounding and pounding, can be silenced by substituting the hydraulic and sonic equipment now on the market.

Of course, silencing is a relative term. For example, what has been accomplished is not to make construction noise a desirable neighbor, but at least to soften some of the naked sounds of construction machinery.

The question always raised is: what noise level? The German Health Ministry realizes existing knowledge does not permit drawing a hard and fast line to divide health-injuring noise from noise that is merely “annoying.” Lacking a specific exposure limit (combination of time and noise level), Germany nevertheless seeks to promulgate laws requiring the reduction of intense noise–at its sources. In 1965 the West German government put noise curbs on construction projects.

The operator of construction machinery must see to it that all noises which, according to the latest technical developments, it is possible to avoid or minimize are avoided or minimized, and also see to it that the emanation of unavoidable noises from the construction site be kept to the absolute minimum possible. The operation of a machine that does not comply with these stipulations can be prohibited until the noise is reduced. This is much more effective than a fine.

Switzerland was regulating construction noise before 1965. In 1964, Zurich’s noise control office investigated 303 construction sites. Several projects were shut down until the contractors found methods to reduce noise. Austria makes possible an immediate reduction in construction-equipment noise by applying an existing law, the gist of which is that noise made in an “improper” manner is punishable. If noise emanates from a tool that is not technically up to date, it could be interpreted to be an “improperly” made noise. Compressed air equipment lacking muffling would fall into this category.

In America, regulatory agencies, such as the Transit Authority, have the power to curb construction noise without any new legislation. All they have to do is enforce the silencing clause that is standard in many contracts awarded by public agencies. Could any wording be more explicit, or more completely ignored, than the silencing clause in the subway extension contract between the Transit Authority and the contractors? “The contractor must perform all work in such a manner as to create a minimum of noise. He may be required to shield or otherwise cover or insulate his operations so as to restrict the transmission of noise…(he) shall be solely responsible for the performance of the work in a manner which will not create or constitute objectionable noise or other nuisance to the public…”

It is difficult for the urban apartment dweller to believe that the United States National Bureau of Standards was testing home sound insulation as long ago as 1922! It has been publishing the results of such testing since 1939. Its latest guide to noise control in dwellings was published in 1967.

Builders and architects know the laboratory-tested values of more than a hundred varieties of door, floor, and wall constructions. They can get design information from the FHA, and from companies that specialize in noise-rated construction products, such as Owens-Corning and U.S. Gypsum. With this information they can select the proper sound-insulating wall, a floor construction that stops the noise of your neighbors’ footsteps, and the proper materials for halls, doors, windows, as well as techniques for plugging acoustic leaks in piping and wiring openings in walls and floors and installing plumbing and appliances to operate quietly.

The builder and designer can specify the sound-insulating quality of the wall partition desired, as well as floor/ceiling construction. Methods of evaluating the acoustic quality of a finished room have been used in the Netherlands since 1948.

Mechanical equipment–such as central air conditioning motors and dishwashers–can be mounted on isolation mounts on special flooring to prevent sound transmission. Pipes can be isolated from the building structure to prevent converting the structure into a sounding box. Plumbing noises can be eliminated by proper choice of fixtures and careful installation.

One undesirable feature of air conditioning (and mechanical ventilating) is the noise made by rushing air. This noise can be controlled by reducing the velocity of the air stream, lining the air ducts with sound-absorbent materials, or equipping the outlets with mufflers. Fan noise can be reduced by increasing the number of fan blades and staggering the design of the blades to prevent the formation of irritating tones.

The noise of mechanical ventilating and central air conditioning, with its noisy air flow and cooling tower noise, is controllable. ASHRAE, the professional society of the industry, has published detailed technical reports on how to sound-control all types of air conditioning installations. It has evolved a system of noise standards and criteria for single-family homes, apartment houses, churches, offices and schools.

As a matter of fact, silencing techniques are so sophisticated, one company puts out a Short Form for busy designers to use in “calculating the amount and type of noise control desired.” Noisy systems can also be quieted after installation. It is cheaper, however, to introduce noise control at the design stage.

A small detail such as not installing medicine cabinets in the walls and back to back will help eliminate noise transmission between bathrooms.

American Standard advertises a deluxe model kitchen garbage disposal unit that “is a conversation piece…because every word praising it will be easily heard.” If this advertising copy is accurate, the disposal is quiet because the outer shell is constructed of heavy, extra thick fiber glass insulation with a shock-absorbent rubber mounting that cushions noise and minimizes vibration.

Builders, especially in a competitive market, will not incorporate noise control provisions without an incentive. That incentive can be made a part of local building codes by requiring that in addition to standards for fireproofing and safety, homes be built to noise insulation standards. Europeans have long recognized the need for government to provide this incentive. Germany led the way in 1938, and since then, building codes including noise specifications have been adopted in Austria, Belgium, Denmark, England, Finland, France, the Netherlands, Norway, Scotland, Sweden, and Switzerland; not to mention Bulgaria, Czechoslovakia, and the Soviet Union.

Apparently, not all of these countries require that private building meet their national standards. However, private builders, as in Switzerland, are encouraged to adhere to them, by the realization that a new tenant who finds himself deprived of the peaceful use of his apartment can go to court and obtain a rent reduction.

Zoning is a traditional form of noise control. Its use, legend has it, goes back to the days of the ancient Sybarites, who some 2,500 years ago were intelligent enough to exclude blacksmithing, cabinetmaking, and other noisy industries from the residential city.

Zoning ordinances are used today primarily to protect residential areas from noises made within factories and commercial installations. Decibel limits are set on the amount of noise that can be radiated from within the factory to its boundary.

In Czechoslovakia, factories that produce noise exceeding 100 decibels must have a protective belt of 500 meters, and the external noise level at the point nearest any residential area must not exceed 50 decibels by day or 40 decibels at night. In the Soviet Union, plants with equipment causing a noise level over 90 decibels must be located on the leeward side of the nearest residential area and separated from it by an acoustic buffer zone, landscaped and planted with trees. Beyond this zone the noise must not exceed a specified level.

In Germany, certain industries have to receive a permit before being able to build or operate a plant, and this permit will only be granted if all technical advances are harnessed in the interest of noise abatement. Should an installation not abide with this regulation, the permit may be withdrawn.

The zoning concept can be expanded to offer protection from many undesirable noises. Coral Gables, Florida, applies zoning to noises made within the home, especially to residential air conditioning systems, to protect neighbors from each other and give them freedom from unnecessary noise. Unnecessary is interpreted to mean capable of being muffled, or designed to make less noise. By placing air conditioner noise control in a zoning ordinance instead of the typical anti-noise ordinance, Coral Gables avoided the impasse of having to establish a case for health damage.

(In reviewing some of the few statutory limitations on air conditioning, I asked a consulting engineer if society wasn’t being too harsh on the industry, since there were no universal standards. He replied, “They don’t need special standards to make an air conditioner that permits room conversation without straining my voice.”)

Dallas, Texas, offers an example of how a public health department can utilize a zoning ordinance. In that city, the health department regulations use the noise standards incorporated in the Dallas Zoning Ordinance. The Village of Port Washington, on Long Island, used its zoning code to prohibit a company from using part of its industrial-zoned property for a private helicopter site. Where there is a commitment, there is a way.

As a last resort, a specific noise source can be banned.

One of the first sources to go in recent history was the poubelle, the French garbage can. In Paris, household poubelles must be of a design that permits noiseless handling of the lid and the can body. The ordinance introduced in 1959 gave householders until January 1, 1963–three years–to replace existing cans; after that date, those that did not meet the “noiseless” specifications were not emptied.

In the United States at least one local government arranged the banning of automatically operated bells, chimes, and gongs used on ice cream trucks. When enforcement of a curfew on sound signals after 9:00 P.M. proved impossible, New York City’s former Markets Commissioner Gerard Weisberg took action. He acknowledged the benefits of mobile ice cream vending: convenience and the summer employment offered young people on vacation. He only objected to the nuisance value of the automated signals. In 1968 he issued a new regulation, making their use illegal. He figured that a vendor with hand bells would be too busy dispensing ice cream to ring the bell often enough to create a nuisance in the neighborhood.

Administrative regulations and licensing are not the only means available to government for achieving quiet. Government agencies can specify quiet design when purchasing traditionally noisy machines and equipment. This is what New York City did to some degree when it was replacing its fleet of garbage trucks. If a silent submarine can be ordered to “tuned” frequency specifications, so can garbage trucks, air compressors, and jackhammers. Municipal governments will need to learn how to cooperate with vendors to achieve design goals.

The public will have to insist that a rigid bidding system in government does not stifle noise abatement. The manufacturer of the quieter products should be rewarded with a purchase order.

Though this book emphasizes the noises of machines, there is also the important category of people-made noises, noises that could be eliminated by the exercise of personal discretion.

Assuming that the motorcycle as manufactured was designed for quiet operation, the motorcyclist could control the amount of noise his vehicle emits by accelerating slowly, refraining from revving his motor while idling, not removing or de-activating his muffler. Motorcycle trade associations, sensitive to anti-motorcycle sentiment and fearful of restrictive legislation, caution their customers to be good neighbors. In a booklet given to purchasers, they urge the cyclist not to remove the internal baffles of his muffler, add cut-outs, replace quality mufflers with cheap ones, or, worse yet, with “Hollywood type” megaphone mufflers. As an incentive not to tamper with the muffler, the Motorcycle, Scooter and Allied Trades Association cautions cyclists that the excessive noise generated by “adjusted” mufflers may actually reduce the performance of the engine, increase engine temperature, burn out valves, and create other conditions that will impair or destroy the efficiency of the power plant.

All manufacturers of radios and other volume-controlled noise emitters should provide some means of urging volume reduction, especially at night. The use of portable radios in public places can be controlled by local ordinance. In France the prefects of the individual departments were given this instruction: “…transistorized apparatus may only be used in public with their loud speakers turned off (use earphones only).” In England and Wales no one may use a radio in public so as to cause annoyance, and radios are specifically prohibited in London’s Hyde Park. Local buses in Washington, D.C. ban radios.

People can eliminate many noise problems by proper behavior. Housewives using noisy appliances can stop during meal hours, and certainly avoid mechanical cleaning during hours of sleep. Pianists can install damping devices on their instruments so that their practicing does not convert adjacent apartments into concert halls. An attempt can be made to restrict the noisy play of children to non-sensitive locations. Dogs can be trained not to bark, and parents can implant in their children a good example of acoustic manners by driving without excessive use of the auto horn.

People are all too frequently unaware of how their noisemaking activities impinge on their neighbors. Requests for quiet are interpreted as personal attacks, and raise hackles. There is growing interest in the Swedish concept of a third-party intermediary, the ombudsman, an official who can function as the citizen’s advisor, and champion his grievances against the injustices of government, or help him if he finds he must take his neighbors to court.

At the same time that man’s seeming obsession with speed and convenience have generated the noisiest epoch in his history, his intelligence has produced the means of enjoying the fruits of technology without suffering from its acoustic waste products. What is needed is a widespread concern for protecting the human being and his environment from excessive noise. Were there such concern the making of noisy products would soon become illegal. Will anybody care?