138 research outputs found

    Methods for measuring the loudness and noisiness of complex sounds

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    Physical and temporal aspects of sound which influence the rating of subjective noisiness are intensity, spectrum shape and bandwidth, spectral complexity, and duration. Objective rating methods include a graphic method, full octave and one-third octave methods, and methods that measure one value over all frequencies

    Prediction of effects of noise on man

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    Quantitative prediction of human effective perceived noise intensitie

    The methods of paired comparisons and magnitude estimation in judging the noisiness of aircraft

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    The point of subjective equality in regard to perceived noisiness for each of 14 pairs of aircraft noises was obtained using both magnitude estimation technique and the method of paired comparisons. Both methods gave approximately the same estimates of the points of subjective equality for the noise pairs, and both showed similar correspondence to predictive physical measures. Nevertheless, the two methods appear to have greater face validity to the listeners. However, the magnitude estimation technique appears to be more efficient; for a given level of reliability it requires approximately 50% of the testing time required by the paired comparison method. The functions relating physical intensity to the estimated magnitude of subjective noisiness had slopes ranging from about .61 to .29 for the aircraft noises employed in this study, indicating a required change of about 5 to 10 db for a doubling in subjective magnitude. Some physical units of noise measurement were found to be very predictive (standard errors of estimate as low as 1.9 db) of the subjective judgements of noisiness

    Perceived noisiness under anechoic, semi-reverberant and earphone listening conditions

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    Magnitude estimates by each of 31 listeners were obtained for a variety of noise sources under three methods of stimuli presentation: loudspeaker presentation in an anechoic chamber, loudspeaker presentation in a normal semi-reverberant room, and earphone presentation. Comparability of ratings obtained in these environments were evaluated with respect to predictability of ratings from physical measures, reliability of ratings, and to the scale values assigned to various noise stimuli. Acoustic environment was found to have little effect upon physical predictive measures and ratings of perceived noisiness were little affected by the acoustic environment in which they were obtained. The need for further study of possible differing interactions between judged noisiness of steady state sound and the methods of magnitude estimation and paired comparisons is indicated by the finding that in these tests the subjects, though instructed otherwise, apparently judged the maximum rather than the effective magnitude of steady-state noises

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

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    Awakening response of humans to sonic booms and subsonic aircraft nois

    Possible modifications to the calculation of perceived noisiness

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    Modified calculations for relative perceived noisiness of aircraft by human subject

    Effects of sonic booms and subsonic jet flyover noise on skeletal muscle tension and a paced tracing task

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    Effects of sonic booms and subsonic jet flyover noise on skeletal muscle tension and paced tracing tas

    Judgment tests of aircraft noise

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    Psychological tests of human responses to aircraft noise level

    Reliability of laboratory tests of VSTOL and other long duration noises

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    Paired-comparison and magnitude estimations of the subjective noisiness or unacceptability of noise from fixed wing jet aircraft and simulated noise of VSTOL aircraft were obtained from groups of subjects given different instructions. These results suggest that VSTOL noises can be evaluated in terms of their noisiness or unwantedness to people with reasonable accuracy by units of the physical measures designated as PNdBM, with or without tone corrections, and dBD sub 2. Also, that consideration should be given to the use of D sub 2 as an overall frequency weighting function for sound level meters instead of the presently available A weighting. Two new units of noise measurement, PLdB and dB(E), used for predicting subjective noisiness, were found to be less accurate than PNdBM or dBD sub 2 in this regard

    A preliminary study of the awakening and startle effects of simulated sonic booms

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    Awakening and startle effects of simulated sonic boom
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