Showing papers on "Noise pollution published in 1969"

Environmental Noise Pollution: A New Threat to Sanity

Abstract: Standards developed by the U.S. Air Force (the largest employer in the country with a very noisy environment) have led to a recommendation that ear “defenders” be worn if the noise levels exceed 85 decibels. What is not generally recognized is that the level of “ordinary” noise in a community frequently exceeds the 85 decibel level—which has been found injurious in industry. And the end is not even in sight. Just over aviation's horizon is the supersonic transport airplane and its sonic boom. Dr. Anthrop is a research chemist at Lawrence Radiation Laboratory, Berkeley, California. He is a conservationist, and is doing research in noise abatement.

Noise inside motor cars

Abstract: Although the noise levels to which the occupants of motor cars are subjected are generally not high enough, and exposure times not long enough, to have a detrimental effect on the hearing, ones own driving experience confirms that speech interference, fatigue and annoyance certainly occur as a result of the noise. Now that the comfort of the occupants is one of the prerequisites of a good vehicle the control of noise at the design stage is essential if costly modifications and adverse publicity are to be avoided. The results presented in this paper are based on the initial work carried out at the Institute of Sound and Vibration Research During the period 1965/68 on the problems of noise inside motor vehicles. The noise inside some two dozen cars was analysed and from the results the more detailed research programme which is being carried out at the I S V R was planned. The work is primarily concerned with the low frequency noise and in particular the problem of 'boom'. 'Boom' can be defined as a low frequency noise of high intensity, excited by one of engine's unbalanced harmonics, where most of the energy is concentrated at usually one discrete frequency.

NASA Duct Lining Research Program

Abstract: Because of the rapidly increasing noise pollution in the vicinity of large commercial airports, the government established an interagency panel in October 1965 to develop recommendations concerning the implementation of a coordinated noise‐abatement program. A part of NASA's contribution to this program resulted in the awarding of contracts to The Boeing Company and the McDonnell Douglas Corporation in May 1967, directed toward reducing the noise under the flight path of the current large four‐engine fan‐jet commercial transports. This paper is a brief review of the background of these contracts to study and develop nacelle modifications to minimize fan‐compressor noise radiation. The goals and scope of the contracts is discussed and the current status presented.