Showing papers on "Noise pollution published in 1978"

Selective noise disturbance of the information input in short-term memory

Abstract: The present experiment was designed in order to investigate the effects of noise produced intermittently during the input stage of serially displayed visual materials (6-digit lists). These materia...

Noise Control Handbook of Principles and Practices

Abstract: NOISE CONTROL HANDBOOK OF PRINCIPLES AND PRACTICES Engineering, law, health care, architecture and design, transportation, government administration—each in its own way is concerned with the control and elimination of noise pollution from the environment. This handbook provides a basic guide for preparing, enforcing, and meeting noise control requirements. General enough to contain all the essentials of noise control, it is sufficiently detailed to meet specialized needs in areas such as aircraft noise reduction and housing insulation. You need no prior knowledge of the noise control field for a full understanding of this material. Each chapter is written by a recognized expert and concentrates on a particular aspect of noise abatment. The first sections focus on a basic explanation of sound and noise. Here you will discover the theoretical basis for the commonly used measuring techniques, as well as how to judge which instrumentation is best suited to your particular needs and situation. Practical applications of the important and widely used Equivalent Sound Level system of measuring noise are thoroughly explained. Using common industrial and construction situations, the book demonstrates the basic principles of noise control and acoustical treatment in the conservation of human hearing. This coverage includes necessary technical formulas, advance design methods, and explanations of sound test codes and legislation. There is a full discussion of both sides of the airport'aircraft noise controversy. The authors examine the measurement of noise levels, legislative and regulatory efforts to keep these levels with:n safe limits, and the impact of lonj terrfi exposure to noise on the human population. The Handbook deals in realistic teims with the problems of vehicular engine and tire noise levels. And vou will find a complete section on noise leveis In tn« home—how they can adversely effect people and how to design and insulate against them. In addition, the authors fully explain how to go about writing an acceptable Environmental Impact Statement. You learn how to write, word and properly define the limits in noise control ordinances. To round out the comprehensive coverage, you also find a thorough evaluation of the noise levels of recreational activities and vehicles, such as power boats, off-road motorcycles and snowmobiles. Whether you are a layman concerned with the ecological impact of noise or an engineer concerned with machine design, Noise Control will serve as your basic reference to today's critical problems in noise reduction and abatmer. l.

Method of prediction and control of road traffic noise in japan

Abstract: Road traffic noise is one of the most important environmental noise sources in Japan. Before a new road is constructed, predictions of sound levels that will be generated by the traffic are usually made. If the predicted sound level exceeds environmental noise standards, some noise control procedures should be adopted. The paper discusses various methods for predicting road traffic noise based on the road structure and traffic. Also discussed are noise abatement procedures.

Aircraft Noise Identification System By Correlation Technique

Abstract: The growth of environmental noise by traffic, construction, or manufacturing bring increasing interference in listening to television and radio, as well as in other human activities. The Japanese government's national -projects for noise abatement are making progress in the revision of land-use compatibility and sound-proofing of dwellings. Through the Broadcasting Act, the Japan Broadcasting Corporation (NHK) has made a discount of the TV receiver's fee for compensation of interence in listening to TV by aircraft noise within restricted areas around airports and airbases.

What's all the noise about?

Abstract: Light aircraft noise is a growing problem, so much so that internationally proposed noise limits are expected to be enforced in many countries before long. This article highlights the main themes of a conference on light aircraft noise.

The influence of background noise level and signal duration on the judged annoyance of aircraft noise

Abstract: A series of 72 flyover events were assessed by a jury of 35 observers, during 12 separate listening sessions conducted in a controlled test area designed to simulate typical indoor listening conditions Each aircraft signal was superimposed on a controlled random traffic background signal having a duration exceeding that of the aircraft event The presence of a steady mean traffic background noise can reduce the perceived noisiness of aircraft flyover events, provided that the judgment time available is sufficiently greater than the event time (time in excess of background) For a given peak event level, a reduction in associated background noise of 21 dBA is shown to be equivalent subjectively to an increase of 55 dBA in peak event level, with fixed background conditions Although regressions obtained with the noise pollution index, L sub NP, for single event judgments generally showed a lower correlation than the L sub o and L sub p - L sub o regression variables, the score data did show a number of significant trends which are also associated with the LNP index variations computed for single noise events

Effectiveness of shielding in reducing adverse impacts of highway traffic noise

Abstract: Construction of noise barriers or other forms of shielding between residential areas and noisy roadways is one of several approaches to reducing community noise levels Some studies have suggested that the psychological effect of such shielding is greater than its acoustical effect. This suggestion was tested by using home interview data from five pairs of residential sites. The two sites that made up each pair experienced the same noise level at dwellings but had different types of shielding or barriers. It appears that there is no psychological effect for road traffic noise specifically but that there is an effect for attitudes toward overall community noise. This psychological effect appears to be negative for solid noise barriers, low for single rows of trees, and highest for a rows of intervening housing. /Authors/

Wind tunnel investigations of model rotor noise at low tip speeds

Abstract: Experimental and related analytical results on model rotor rotational and broadband noise obtained in the anechoic wind tunnel and rotor facility are summarized Factors studied include various noise sources, effects of helicopter performance parameters on noise generated by a model main rotor, appropriate scaling laws for the various types of main rotor noise, and the effects of intensity and size scales of injected turbulence on the intensity and spectra of broadband noise

Road Noise and Property Values: Some Evidence from the Copenhagen Area

Abstract: Noise has become a major problem in most industrial countries, and the costs of noise control can be expected to rise markedly in the years ahead. Consequently, the question of the optimal noise pollution control level is becoming increasingly important. In this connection, the use of property value studies has been discussed intensely. This discussion has recently been summarized in two reports from the OECD, one by Miler & Wyzga (1976) and the other by Pearce (1976). The intention here is not to review this debate once again, but rather to present some empirical evidence from the Copenhagen area on the relation between road noise and property values.

Initial psychoacoustic experiments on the human response to transmission line audible noise

Abstract: A project is underway to investigate human response to transmission line audible noise. This project is developing a psychoacoustic data-base to determine the extent to which present measurement scales and human response criteria are appropriate for evaluating the environmental impact of transmission line audible noise, and to suggest different scales and criteria if necessary. A realistic listening room was used for psychoacoustic experiments in which a listener was given choices between various acoustic environments, including corona sounds, while reading a book. In another experiment groups of participants rated various sounds for their annoyance level while watching television programs. Results indicate that despite its relatively low sound level, corona noise is equally aversive to certain other environmental sounds that are 8 dB higher in sound pressure level. All of the common frequency weighting scales underestimate the aversiveness of corona noise relative to other environmental sounds. From a limited sample of comparison sounds, corona noise was found to be roughly equal in aversiveness to the noise from a room air conditioner. Knowledge of the source of the noise did not affect the relative aversiveness of corona noise as presented in the laboratory. The high-frequency hissing and crackling components of corona noise aremore » more aversive than the low-frequency humming and buzzing components. There are distinctly different kinds of corona noise which differ both in frequency spectrum and relative aversiveness. Thus, in order to assess environmental impact, long-term sampling of corona noise from different lines may be needed. Similar results were obtained from experiments involving reading and television viewing as participant activities, indicating consistent and generalizable findings. (JGB)« less

Helicopter noise regulations: An industry perspective

Abstract: A review of helicopter noise measurement programs and noise reduction/economic studies of FAA is given along with a critique of a study which addresses the economic impact of noise reduction on helicopter noise. Modification of several helicopters to reduce noise and demonstrate the economic impact of the application of the current state-of-the-art technology is discussed. Specific helicopters described include Boeing Vertol 347 Helicopter, Hughes OH-6 Helicopter, and Hughes 269C Helicopter. Other topics covered include: (1) noise trends and possible noise limits; (2) accuracy of helicopter noise prediction techniques; (3) limited change possibilities of derivatives; and (4) rotor impulsive noise. The unique operational capabilities of helicopters and the implications relative to noise regulations and certification are discussed.

Noise control in ships

Abstract: Within the sphere of noise and its control, the problems for passengers include those of ensuring adequate privacy between adjacent cabins and of keeping the transmission of noise from machinery spaces to a suitably low level. At the same time, the risks of permanent hearing damage to the crew due to prolonged exposure to high noise levels have resulted in the requirement for noise control in machinery spaces. The question of privacy is also becoming increasingly important in non-passenger ships, such as tankers, which can undertake long voyages, sometimes with family units on board. Methods of noise rating and criteria for various spaces within ships are discussed, and methods of sound insulation are analyzed.

Commercial airport operations and community noise criteria

Abstract: : This study program involved response of 48 persons to seven different simulated commercial airport noise environments. Each exposure period was of 1-1/2 hours duration and subjects experienced and rated eight of these 1-1/2 hour noise exposure periods. The test environments simulated a conventional living room environment. Number of aircraft noise intrusions per exposure period ranged from 6 to 18 flyovers and indoor Leq(dBA) levels ranged from 38.9 to 52.1 dB. Some of the conclusions are: Noise exposure from a 'new' aircraft fleet mix (circa 1980) is clearly more acceptable than that from an 'old' fleet mix (circa 1965). Commonly used noise exposure methods such as NEF, Leq, and mean peak dBA are level dependent. Depending on the noise exposure method used, 2.5 to 4.0 dB is perceived as a reliable change in noise exposure. Predictive capability of a noise exposure method is a function of the engineering calculation procedure employed to weight the acoustic energy. Mean peak level exposure methods have greater predictive capability than energy summation methods. Leq(dBA) is a relatively poor predictor. (Author)

Roadside barrier effectiveness, noise measurement program

Abstract: A field noise measurement program was conducted to assess the performance of a variable height highway noise barrier with and without an acoustic lining material. The barrier site on Interstate I-93 in Andover MA was located adjacent to an acoustically similar unobstructed site. The noise emissions from a common stream of vehicular traffic were measured at both sites simultaneously and compared to evaluate the performance of the barrier. A 1000-foot-long barrier at effective heights of 2.8, 6.8, 10.8 and 14.8 feet was measured and evaluated. Included in the report is the statistical noise data from fourteen measuring systems for each barrier configuration along with spectral data, traffic information and meteorological conditions.

Concorde noise-induced building vibrations john f. kennedy international airport

Abstract: The outdoor/indoor noise levels and associated vibration levels resulting from aircraft and nonaircraft events were recorded at eight homesites and a school. In addition, limited subjective tests were conducted to examine the human detection/annoyance thresholds for building vibration and rattle caused by aircraft noise. Presented herein are the majority of the window and wall vibration data recorded during Concorde and subsonic aircraft overflights.

Transmission of combustion roar from burners and furnaces

Abstract: In studies directed toward the problem of industrial combustion noise, Battelle Columbus Laboratories prepared cold-flow simulations of tunnel-type burners to determine the effect of flow on acoustic performance. The data show a strong decrease in predicted amplification of the burner noise as a result of including the effect of the acoustic waves traveling through the air- and fuel-supply lines. Furthermore, increases in flow velocity also decrease amplification levels. Disregard of these flow effects can result in overpredictions of noise levels during equipment design.

Analysis of Environmental Noise Monitors

Abstract: : This report establishes criteria and performance guidelines desirable in environmental noise monitors that are achievable through state-of-the-art technology. To assess this technology, the performances of 10 available units were evaluated based on the following points: (1) Data reduction methods and analytic results; (2) Dynamic range; (3) Impulse response; (4) Environmental considerations (temperature extremes and wind); (5) Shock resistance; (6) Ease of operation; and (7) Likelihood of errors in operation. Favorable and unfavorable features discovered during the investigation of these units are discussed, as well as desirable features found to be absent in all of the units. Based on the study and the conclusions, the operating characteristics of an ideal unit are recommended.

Construction-Site Noise Control Cost-Benefit Estimation Technical Background.

Abstract: : Presented are methods of estimating noise level at a construction site, methods of noise reduction and control at a construction site, and the associated costs for this reduction with the emphasis on equipment noise control. (Author)

Projecting the impact of new medium and heavy truck noise regulation strategies on community noise levels

Abstract: This paper discusses in some detail the mathematical model input data used by the Vehicular Noise Control Department of the General Motors Environmental Activities Staff to project the effects of various medium and heavy truck noise regulation strategies on future community noise levels. The model projects that, for two typical traffic situations, the reduction of new truck sound levels below current requirements does not result in a corresponding decrease in community noise levels. Furthermore, the potential benefits anticipated from the implementation of new truck noise regulations will not be realized without the effective enforcement of operator in-use standards and the control of truck tire noise.

Airframe Aerodynamic Noise- Total Radiated Acoustic Power Approach

Abstract: During flight the noise radiated by aircraft is emanating from two distinct types of sources One source is the propulsion system and the other is the nonpropulsion system noise, or airframe noise, associated with movement of the aircraft through the atmosphere The purpose of this effort was to study airframe noise using a total radiated acoustic power approach Methodology was developed to accurately calculate the total acoustic power by using measurements from an array of microphones during aircraft flyover This methodology was applied to Schweizer 2–32 glider flyovers and it was found that for an aerodynamic configuration (no flaps, wheels, wheel wells, etc) the total acoustic power can be obtained from one flyover measurement by assuming the directivity is nearly equal in all directions This assumption was shown to be valid for the glider and is assumed valid for any aircraft in an aerodynamic configuration The detailed methodology developed is still useful since most commercial aircraft land in