摘要:

A small part of a focused laser beam in a Mach–Zehnder arrangement is used for the detection of high‐frequency pressure waves. The interferometer is stabilized on an interference slope by means of a simple electro‐optical feedback system. The method introduces only little perturbation to the pressure field and yields the true pressure historyp(t) with a submicrosecond time resolution. Several examples of registrations show the capability of this ideal microphone.

ISSN:0001-4966    

DOI:10.1121/1.381339

出版商:Acoustical Society of America    

年代:1977

数据来源: AIP

摘要:

The application of the finite‐element method of analysis to investigate the geometric and material factors which affect the open‐circuit voltage sensitivity of a class of underwater acoustic hydrophones is discussed. This class of hydrophones consists of an air‐filled, right‐circular, piezoelectric ceramic cylinder with flat nonpiezoelectric circular disk end caps. The study examines the factors which constrain the motion of the cylinder in a real hydrophone and cause the open‐circuit voltage sensitivity to be less than the value of an ideal hydrophone predicted by the equations developed by R. A. Langevin [J. Acoust. Soc. Am. 26, 421–427 (1953)]. Curves are presented to allow an estimate to be predicted of the reduction in the open‐circuit voltage sensitivity which a particular design will produce, and a comparison is made between these predictions and empirical data measured on various hydrophone configurations.

ISSN:0001-4966    

DOI:10.1121/1.381340

出版商:Acoustical Society of America    

年代:1977

数据来源: AIP

摘要:

An asymptotic expansion in inverse powers of the wave number is derived for an integral of a type often encountered in the theory of wave propagation in inhomogeneous media. The procedure, which is essentially a forward‐scatter approximation, yields all the terms of the expansion. In contrast, the conventional forward‐scatter approximation is found to yield correctly only the first term of the expansion.

ISSN:0001-4966    

DOI:10.1121/1.381341

出版商:Acoustical Society of America    

年代:1977

数据来源: AIP

摘要:

The contour numerical integration method can be used to calculate nearfield beam patterns of continuous end‐fire line arrays with arbitrary amplitude shading. Other applications include parametric virtual arrays and scattering.

ISSN:0001-4966    

DOI:10.1121/1.381342

出版商:Acoustical Society of America    

年代:1977

数据来源: AIP

摘要:

Tests were conducted in an anechoic chamber to determine the effect of pure tones on speech intelligibility. The results indicate that in the presence of aircraft‐type noise in which combinations of tones and noise are held at a constantA‐level, intelligibility is either unaffected or actually increased by addition of tones in the 2–4‐kHz range.

ISSN:0001-4966    

DOI:10.1121/1.381343

出版商:Acoustical Society of America    

年代:1977

数据来源: AIP

摘要:

The assumption that a person’s hearing cannot beimprovedby aging, noise exposure, or any other otologically pathogenic agent, has the logical consequence that an initially normal distribution of hearing in a given population cannot remain so after the action of the pathogenic agent. The distribution must become skewed. Extrapolations that are often made assuming normal distribution may be practical approximations but they have no logical foundation.

ISSN:0001-4966    

DOI:10.1121/1.381344

出版商:Acoustical Society of America    

年代:1977

数据来源: AIP

摘要:

From two to five frequency peaks, representing sustained portions of white‐throated sparrow (Zonotrichiaalbicollis) song, were derived using a Ubiquitous Spectrum Analyzer for each of more than 300 recorded songs from 58 different birds. After conversion to cents, a logarithmic unit, each bird’s song data were averaged and placed into three distributions: largest interval in whole song, largest interval between adjacent notes in each song, and all intervals between adjacent frequency peaks in each song. These three distributions plus another from African shrike data previously published by Thorpe did not significantly correlate with a distribution derived from commonly used Western musical scales. It is therefore suggested that utilization of Western musical notation may lead one to overemphasize the ’’musical’’ quality of bird song.

ISSN:0001-4966    

DOI:10.1121/1.381345

出版商:Acoustical Society of America    

年代:1977

数据来源: AIP