摘要:

Measurements were made of the acoustical absorption introduced by various configurations of draperies into a small reverberation room. The results are presented and compared here.

ISSN:0001-4966    

DOI:10.1121/1.1910623

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

The present experiment employed 20 college students who demonstrated an ability to make determinations of interruption or continuity in a random noise signal that alternated with a tonal burst. The primary purpose of this experiment was to investigate the effects of the duration the temporal location of the interpolated signal on the perception of continuity under monaural presentation. The effect of frequency of the interpolated tone was also evaluated. The results showed that the perception of continuity in the noise was affected by both the duration and frequency of the interpolated tonal signal. The location of the interpolated signal had no significant differential effect on continuity thresholds.

ISSN:0001-4966    

DOI:10.1121/1.1910624

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

Poststimulatory contralateral masking of pure tones at frequencies 200‐1000 cps are determined on normal‐hearing subjects. The masker was a high‐frequency band noise. Delay interval and noise level have been varied. The masking effect is most probably caused by the middle‐ear muscle reflex, but it seems not possible, on basis of the experiments, to decide whether other mechanisms also are involved.

ISSN:0001-4966    

DOI:10.1121/1.1910625

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

The problem of scaling the central effect of auditory stimulus intensity,I(in power units), is considered, and it is argued that there need not be a unitary neurophysiological correlate for “loudness.” Different psychophysical tasks may draw on different central measures of stimulus intensity. A “metric dimension,”L, which the subject may use in making quantitative judgments, is distinguished from a more peripheral “discriminal dimension,”E, involved in the immediate processing of the stimulus input. Binaural intensity summation data are used to derive the form of the function relatingEtoI, and it is shown that for any particular range of intensities this can be approximated by a power function,E = kIn, where the exponentndepends on the range of intensities used, approximating one near the absolute threshold and decreasing as over all intensity increases. On the assumption that with binaural stimulation the over‐all loudness is determined by the sum ofELandER, the effects produced by the stimuli to the left and right ears, linear equiloudness curves are obtained.

ISSN:0001-4966    

DOI:10.1121/1.1910626

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

Previous knowledge is reviewed relevant to contralateral remote masking (CRM)—the elevation in threshold of a low‐frequency sinusoid the presence of a high‐frequency band of noise in the opposite ear—and series of additional observations is presented. CRM is nearly as great (1) in ears with paralyzed middle‐ear muscles as in normal ears, (2) for bone‐conducted as for air‐conducted test tones, or (3) when a 50‐msec tone pulse occurs simultaneously with the onset of the masking pulse as when it is presented half a second later. Furthermore, (4) the gradual decrease of CRM with time, in the presence of a sustained masker, is not affected by abrupt changes in frequency or level of the masker, and (5) only a low negative correlation between CRM and auditory fatigue exists. These facts all indicate that the middle‐ear muscles play only a minor role in CRM. The course of adaptation of CRM is shown to parallel the course of development of perstimulatory fatigue. It appears, therefore, that CRM represents primarily central masking arising at one or more centers receiving afferent innervation from both right and left ears, and that the change in time of CRM can be ascribed to adaptation processes either in the noise channel or, via the efferent system, in the contralateral channel. Implications of this formulation in regard to auditory fatigue from diotic and dichotic exposure to noise is discussed.

ISSN:0001-4966    

DOI:10.1121/1.1910627

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

Relative importance of different frequency regions in binaural release from masking (for detection) and binaural gain in intelligibility was investigated. Experiments showed that the release from masking (SπN0 case) for single words in high‐level, broad‐band Gaussian noise is roughly 13 dB and is determined primarily by interaural phase opposition in the low‐frequency (<500 Hz) region. The binaural gain in intelligibility at the 50% level was on the order of 6 dB and only partly dependent on interaural phase opposition in the low‐frequency region. Interaural amplitude differences were not considered in the investigation. Subjecting the speech to a large interaural time dealy with the noise binaurally in phase resulted in a relatively constant masking level difference approaching 13 dB over the measured range from 0.5 to 10 msec. The corresponding binaural gain in intelligibility at the 50% level was on the order of 3 dB.

ISSN:0001-4966    

DOI:10.1121/1.1910629

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

In a recent experiment involving intelligibility testing, the response curve (intelligibility function) was found to flatten off sharply at moderately high intelligibilities. A sequential strategy of the up‐down‐transformed‐response (UDTR) type was used in order to concentrate observations in the symmetric region of the curve. The transformed‐response curve showed the departure from symmetry at a much higher intelligibility level. Precision of estimation for the 50% level was found to be higher than for the simple up‐and‐down procedure. The technique is designed for situations in which it is difficult or impossible to vary the step size.

ISSN:0001-4966    

DOI:10.1121/1.1910630

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

The focusing of waves resulting from an idealized explosion—for example, the bursting of a spherical balloon—is examined in a viscous medium using the linearized equations of fluid dynamics. As expected, the structure of the viscous solution closely resembles that of the inviscid solution, the major difference being that discontinuities permitted by the inviscid theory are replaced by rapid but smooth transitions. It is found that ifp0denotes the initial overpressure contained within a sphere of radiusR, the maximum pressure gain due to the focusing effect is approximately|p/p0| ≈ (R/l)12, wherepis the pressure at the center of the sphere andlis the mean free path in the gas being considered.

ISSN:0001-4966    

DOI:10.1121/1.1910631

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

The attenuation of plane sinusoidal acoustic waves due to the electromagnetic radiative properties of the 15‐μ band of carbon dioxide and the 6.3‐μ band of water vapor have been calculated for a wide range of acoustic wavelengths. These bands are found to be less important than the 25‐μ band of water at short wavelengths, but more important than the latter at very long wavelengths.

ISSN:0001-4966    

DOI:10.1121/1.1910632

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

A perturbation method for the treatment of multiple scattering of acoustic waves by two arbitrary cylinders is extended to the case of elastic waves of plane strain. Interaction terms of monopole and dipole type are given explicitly.

ISSN:0001-4966    

DOI:10.1121/1.1910633

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP