摘要:

A new sound transmission loss measuring facility has been in use at Riverbank Acoustical Laboratories for more than a year now. This paper describes the two reverberation rooms, installation of the test panel, instrumentation, and measurement technique. The several checks made for measurement accuracy and repeatability are discussed. Test results are given comparing the old method of test with the new, and results are also given for a folding door measured at four testing laboratories in the United States and Canada.

ISSN:0001-4966    

DOI:10.1121/1.1909459

出版商:Acoustical Society of America    

年代:1958

数据来源: AIP

摘要:

It is argued that a loudness scale based on the discriminability criterion would be better than one based on those methods which assume that direct numerical responses adequately reflect the nature of the loudness experience. The evidence and argument presented show: First, there is just as good a logical basis for accepting the discriminability criterion as for accepting the direct response criterion. In both cases we have to assert face validity which is arbitrary and may be incorrect. Second, the scales based on the discriminability criterion show less interobserver variability, are influenced less by specific experimental conditions, and are less affected by stimulus context than scales based on the fractionation procedure—the major direct response method used. Third, and most important, most of the direct response procedures themselves give results which agree with scales based on a discriminability criterion. It is, in fact, only the ratio scaling or fractionation procedures which give results at variance with all the rest.

ISSN:0001-4966    

DOI:10.1121/1.1909436

出版商:Acoustical Society of America    

年代:1958

数据来源: AIP

摘要:

An extremely serious operational problem is the maintenance of a high level of visual target detection performance during long periods of watch. Will a loud auditory signal aid in the maintenance of a high performance level under these conditions? Apparently, it will. When the failure to detect a target was coupled with the occurrence of the blast of a truck horn, average visual target detection percentages increased substantially, especially for the less proficient observers.

ISSN:0001-4966    

DOI:10.1121/1.1909438

出版商:Acoustical Society of America    

年代:1958

数据来源: AIP

摘要:

The present study measures the temporary threshold shift (TTS) following two conditions of high‐level noise exposure: (1) a control condition where the high‐level noise is preceded by a period of silence; (2) an experimental condition where the high‐level noise is preceded by noise levels which alone produce no apparent TTS. When the non‐TTS‐producing noise was coupled with the high‐level noise, a greater threshold shift resulted than when equivalent periods of silence preceded the same high‐level noise.

ISSN:0001-4966    

DOI:10.1121/1.1909440

出版商:Acoustical Society of America    

年代:1958

数据来源: AIP

摘要:

This paper presents the results of an experimental investigation of the detection of a signal in noise as a function of signal ensemble size and ensemble frequency range. By signal ensemble size we mean the number of signals of different frequency that are equally likely to occur and which the observer must try to detect. By ensemble frequency range we mean the frequency separation between the lowest and the highest frequency signals included in that ensemble. Data are presented for the four observers who took part in the experiment. The results obtained are compared with predictions based upon three mathematical models. Using efficiency measures, the results obtained are also compared with performance expected of a mathematically optimum detector. Finally, the possibility is suggested that the models discussed are not necessarily mutually exclusive, but rather complementary in the over‐all view of detection.

ISSN:0001-4966    

DOI:10.1121/1.1909442

出版商:Acoustical Society of America    

年代:1958

数据来源: AIP

摘要:

Hearing thresholds were measured for two subjects over a frequency range of 250 cps to 4000 cps. These measurements were made both in air and in water. When threshold intensity levels are compared, it is shown that the greatest loss in hearing acuity in water occurred over the frequency range from 500 cps to 2000 cps and amounted to approximately 20 db, while below 300 cps the threshold intensity in water was lower than that in air. Measured intensity levels for an underwater swimmer speaking into a face mask are also presented.

ISSN:0001-4966    

DOI:10.1121/1.1909444

出版商:Acoustical Society of America    

年代:1958

数据来源: AIP

摘要:

This report is concerned with the nature of the mean output of a single correlator receiving system when the input is a narrow frequency band signal arising from a localized source in space. The signal is received by two uniform, collinear arrays having an equal number of omnidirectional receivers. The mean output as a function of steering is bounded by the product of the space factors of the two arrays, so that the gross nature of the mean can be determined by investigating the main lobe width and side lobe level of the space factor product. These two quantities are studied as functions of the number of receivers, the receiver spacing in wavelengths, and source direction.

ISSN:0001-4966    

DOI:10.1121/1.1909446

出版商:Acoustical Society of America    

年代:1958

数据来源: AIP

摘要:

Previous research involving synthetic speech reveals that both the second‐ and the third‐formant transitions play a role in the perception of the voiced stops, |b|, |d|, and |g|. The present experiment examined an additional cue (burst frequency), repeated a portion of the previous research, and collected more information about how the cues act in various combinations.Synthetic speech sounds containing one cue, all possible combinations of two cues, and all possible combinations of three cues were tested on a large group of listeners.Burst frequency was found to act as a cue for the perception of the voiced stops in much the same manner as this variable affects the perception of the unvoiced stops. To the extent that the present experiment overlapped previous research, the two sets of findings were in very close agreement. When cues were combined, they shared in the control of perception in such a way that the contribution of any one cue was largely independent of the nature and the number of the other cues present in the sound. The individual cues seemed to have directional properties somewhat like vectors. The addition of cues produced effects somewhat like the addition of vectors.

ISSN:0001-4966    

DOI:10.1121/1.1909448

出版商:Acoustical Society of America    

年代:1958

数据来源: AIP

摘要:

Detailed measurements of the light intensity of the diffraction orders produced by progressive ultrasonic waves in xylene were made. These were compared to the Raman‐Nath theory and to a modification of this theory by Mertens. Although it was found that in some cases Mertens' modifications were significant, there remain deviations between theory and experimental results which suggest that the actual experimental conditions deviate from the usual theoretical assumptions.

ISSN:0001-4966    

DOI:10.1121/1.1909450

出版商:Acoustical Society of America    

年代:1958

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1909452

出版商:Acoustical Society of America    

年代:1958

数据来源: AIP