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.