Showing papers on "Aircraft noise published in 1970"

Noise exposure forecasts: evolution, evaluation, extensions, and land use interpretations.

Abstract: : Part I describes the evolution of methods for relating aircraft noise exposure to community response in this country, starting with the original Composite Noise Rating (CNR) concept developed in 1952, and with applications specifically to aircraft noise in 1957 under Air Force sponsorship. The development of CNR procedures for civil and military aircraft in 1962 utilizing perceived noise level contours and the development of Noise Exposure Forecast (NEF) procedures in 1967 utilizing effective perceived noise level data are recounted and compared. Part II interprets the noise exposure due to aircraft operations, as expressed in Noise Exposure Forecast (NEF) values, in terms of estimated impact on land uses. Assessments of the land use compatibility with aircraft noise as a function of NEF values are given for a variety of land uses for the purpose of providing guides in land use planning, zoning and in land use development and building construction. (Author)

Awakening effects of simulated sonic booms and subsonic aircraft noise on six subjects, 7 to 72 years of age.

Abstract: This, paper will briefly describe a simulator of sonic booms as the booms would be experienced in houses under the flight path of a supersonic aircraft. It will also describe research on the effects of these simulated booms upon sleeping humans.

Capacity and noise relationships for major hub airports

Abstract: The conflicting goals of increasing capacity at an airport and reducing the noise exposure around that airport are examined. Basically, airport capacity is directly related to aircraft noise exposure such that an increase in capacity means an increase in the noise exposed area surrounding the airport. Several technological and operational noise reduction methods are discussed and it is shown that they can reduce the extent of exposure as capacity is increased. Using John F. Kennedy International Airport as an example, it is demonstrated that if these noise reduction methods are utilized, the capacity of this airport can be doubled and community noise exposure can be reduced below current levels.

Effect of earplugs on passenger speech reception in rotary-wing aircraft.

Abstract: : Direct person-to-person speech communication is sometimes required in rotary-wing aircraft where high levels of noise make the use of hearing protective devices desirable. The question arises as to what effect earplugs would have on the intelligibility of speech in rotary-wing aircraft. Intelligibility test data obtained in flight as well as in a simulated flight situation indicate that the use of earplugs in rotary-wing aircraft will improve the reception of direct person-to-person speech communication. Moreover, their use will afford protection against the deafening, fatigue, and annoyance effects of the hazardous noise present in rotary-wing aircraft. (Author)

Effective perceived noise level evaluated for stol and other aircraft sounds.

Abstract: : A paired comparison experiment was conducted in which a group of thirty two subjects evaluated, in a progressive wave field, the noisiness of sixty recorded aircraft flyover sounds. Thirty of these recordings were from short take-off and landing (STOL) AIRCRAFT. The complete set included a wide range of turbofan, turbojet, piston engine and turboprop powered aircraft in a variety of categories. The results were analyzed to test the ability of the Effective Perceived Noise Leval (EPNL) and other scales to predict the subjective responses. Because the sample of aircraft sounds was unusually large in number, variety, dyanmic range and duration, the test was considered to be severe. The main conclusion of the study is that the EPNL procedure performs as well for the STOL sounds as it does for the CTOL (conventional take-off and landing aircraft) sounds and may thus be used with equal confidence for rating the sounds of aircraft in both classes. When the sounds were divided into propulsion system categories it was found that EPNL, in common with other scales, performed most consistently for jets, piston engined aircraft and turboprops, in that order. In general, the integrated duration correction proved superior to an approximate correction based on the 10 dB-down duration. Analysis of the results showed that the average magnitude of the tone-correction was more than 3 dB and that corrections were automatically applied in practically all cases. In the case of propeller aircraft sound it is apparent that low frequency harmonics invoke tone corrections, whereas the subjective results suggest they are not required. (Author)

Effects of noise on commercial v/stol aircraft design and operation

Abstract: This paper is based on a study performed under a NASA Contract (1) in which the acoustical signatures of several classes of large V/STOL aircraft were predicted, synthesized electronically, and evaluated for annoyance. Perceived Noise Levels were established in a manner similar to that which has been employed for jet airplanes. The paper describes the methods of simulation and testing and discusses the results in terms of criteria for successful commercial operations and the noise reduction research which will be required to attain this goal.

Noise exposure forecast contours for 1967, 1970 and 1975 operations at selected airports

Abstract: : Noise Exposure Forecast (NEF) contours resulting from 1967, 1970, and 1975 aircraft operations are depicted for 28 airports. Included are contours for large, medium and small commercial airports and general aviation airports. The NEF contours define land areas having different land-use compatibility with respect to aircraft noise; hence, the NEF AREAS MAY BE USED AS A GUIDE TO LAND-USE PLANNING AND ZONING AND AIRPORT DEVELOPMENT. The NEF contours are based upon the aircraft noise described in terms of effective perceived noise levels (which includes corrections for duration and presence of discrete frequencies) plus adjustments for the number of operations for daytime and nighttime periods. (Author)

Cockpit noise exposures associated with the operation of fixed-and rotary-wing aircraft

Abstract: : Noise levels measured within the cockpits of 126 fixed- and rotary- wing aircraft were tabulated and arranged into stereotyped sets of exposure envelopes. The noise data from which these envelopes were derived represent 'typical' unprotected exposures encountered within 12 different categories of fixed- and rotary-wing aircraft during conditions of 'normal cruise.' Extreme or unique noise exposures were deleted from the study.

Applying simulation techniques to an air traffic control study

Abstract: Air traffic in the United States has expanded rapidly due to the rising demand of passengers for rapid, convenient, comfortable transportation, the increasing use of air freight, and the soaring growth of general aviation, which includes the recent proliferation of business jet aircraft. The primary purpose of the United States air traffic system is the safe, efficient movement of air traffic; it is required to accommodate all aircraft which place a demand upon it, from the large, fast commercial jet airliner to the small, slow privately owned airplane, and in so doing must accommodate the widely varying navigational and communications capabilities and performance characteristics of these aircraft.Aircraft types can change or be modified in a short time to accommodate a market—witness the increase in instrument flight capabilities among general aviation aircraft, or the experimental introduction of STOL aircraft into commercial service. Changes in the air traffic system, with its airports, air routes, navigation, and communication facilities, and geographic subdivisions, require much more time, partly because the system has to maintain service as it is being changed. Demands to modernize the system and to provide more airports have come from users and from Congress, while people living in neighborhoods of existing airports have demanded decreases in the aircraft noise levels emanating from these airports.

Attenuation of aircraft noise by wood-sided and brick-veneered frame houses

Abstract: Jet aircraft noise attenuation characteristics of wood-sided and brick-veneered frame houses

Noise exposure forecast contours for aircraft noise tradeoff studies at three major airports

Abstract: : The relative effectiveness of three changes in aircraft operating procedures and/or aircraft hardware in reducing noise exposure around three major airports (O'Hare International Airport, Chicago, John F. Kennedy Airport, New York, and Los Angeles International Airport) were rated by determining the relative change in land areas falling within Noise Exposure Forecast (NEF) 30 and 40 contours. For projected 1975 operations, sets of NEF contours were calculated for changes which included: power cutbacks after takeoff and two segment approaches for all aircraft, and retrofit of current four-engine turbofan aircraft with either acoustically - lined nacelles or with a 'quiet' engine under development by NASA.

Technical evaluation report on agard specialists' meeting on 'aircraft engine noise and sonic boom'.

Abstract: : Contents: Aircraft noise source; Noise prediction; Jet noise source; Fan and compressor noise source; Design for noise source control; Acoustic path control; Acoustic impact on receiver.

Possible Modifications to Procedures for the Calculation of Perceived Noisiness

Abstract: An examination is made of three sets of data pertaining to paired‐comparison judgment tests of the perceived noisiness of, primarily, aircraft noise: (1) 17 studies for which perceived noise levels (PNLs) calculated from peak of maximum sound‐pressure levels of 143 noises are available; (2) a field study for which effective perceived noise level (EPNL is equal to PNL integrated over the duration of a noise) as well as maximum and peak PNL of 18 different aircraft noises are available; and (3) a study for which PNL and EPNL of impulsive noise (sonic booms) and the noise of subsonic aircraft are available. From these data, it is concluded that: (1) the perceived noisiness of aircraft sounds can best be predicted by combining 13‐ or 1‐oct‐band sound‐pressure levels below 355 Hz in certain ways (to account for the critical bandwidth of the ear) prior to the calculation of PNL or by the use of a sound‐level meter with a frequency weighting herein designated as D2; (2) time‐integrated measures of sound are sign...

Noise exposure forecasts: evolution, evaluation, extensions and land use interpretations. final report

Abstract: THIS TWO-PART REPORT DISCUSSES THE CONCEPT OF NOISE EXPOSURE FORECASTS (NEF) FOR PREDICTING A SINGLE NUMBER RATING FOR THE CUMULATIVE NOISE CAUSED BY AIRCRAFT OPERATIONS INTRUDING INTO AIRPORT COMMUNITIES. PART I DESCRIBES METHODS FOR RELATING AIRCRAFT NOISE EXPOSURE TO COMMUNITY RESPONSE. PART 2 INTERPRETS THE NOISE EXPOSURE DUE TO AIRCRAFT OPERATIONS (IN NEF VALUES) IN TERMS OF ESTIMATED IMPACT ON LAND USE FOR THE PURPOSE OF PROVIDING PLANNING AND DEVELOPMENT GUIDES. /TRRL/

Real‐Time Spectral Analysis of Aircraft Flyover Noise

Abstract: The noise produced on the ground by a jet aircraft flying overhead is a signal whose amplitude varies by as much as 40 dB and whose duration may vary from 10 to 30 sec or more. Recent specifications for aircraft noise require a 12‐oct band frequency analysis over the audible frequency range of this signal at each 0.5 sec interval of the time pattern. We describe a hybrid data analysis system used for this purpose which consists of a Hewlett‐Packard model 8054‐A Real‐Time Spectrum Analyzer controlled by a DEC PDP‐8 computer using a conversational language in the control program. The effect of analyzer time constants and various scanning rates on data repeatability and reliability are presented. These results are compared to those obtained with the more commonly used filter‐graphic level recorder combination.

Investigation of DC-8 nacelle modifications to reduce fan-compressor noise in airport communities. Part 3 - Static tests of noise suppressor configurations, May 1967 - October 1969

Abstract: Static tests of noise suppressor configurations of DC-8 aircraft nacelle modifications to reduce fan-compressor noise levels - Part 3

Effects of noise from aircraft in flight

Abstract: One of the aims of this paper is a presentation of the results concerning the frequency characters, noise contours, NNI contours and PWL (A) of aircraft in flight obtained from the measured values of sound level in the vicinity of Osaka International Airport. Another aim is a suggestion of some remedies for the noise-problem around the airport.The noise from aircraft in flight in the area in question was found the most intense in the slender zone right beneath the take-off flight path. In this zone the effects of noise upon the inhabitants are observed unbearable to them, judging from the NNI values there.The first radical step to settle this noise problem is, of course, the removal of the airport itself. For the present, however; in order to reduce the effects of the noise these measures should be taken: (1) putting in force the noise certification by establi shing a noise criterion which will be settled below the present noise level of aircraft within the technological possibility, (2) shifting the present flight paths to improved ones, (3) controlling the number of flights in the airport.