摘要:

An analysis has been carried out to determine the diffracted fields due to directional sources located near rigid planar screens with application to the suppression of noise by acoustic barriers, especially highway barriers. Firstly, the diffracted field due to an arbitrarily oriented point dipole source is obtained by source position differentiation using the classical exact results due to McDonald. The dipole results are then combined with the monopole results to obtain the diffracted fields due to a series of combined sources having arbitrary directivity and orientation with respect to the plane of the screen. It is noted that while the diffraction problem with simple sources and planar screens exhibits reciprocity, diffraction results obtained in the present problem do not exhibit reciprocity with respect to source and observer locations. Typical computed insertion loss results are shown indicating the trends associated with source directionality, source orientation, and source location. Barrier insertion loss reductions, relative to those obtained with simple sources, are noted for vertically oriented directional sources located close to, and below, the diffracting edge.

ISSN:0001-4966    

DOI:10.1121/1.381991

出版商:Acoustical Society of America    

年代:1978

数据来源: AIP

摘要:

The theory of resonance scattering, recently developed for acoustic‐wave scattering from elastic objects and elastic‐wave scattering from cavities, is applied here to the problem of sound scattering from fluid‐filled elastic cylindrical shells in a fluid, in particular air‐filled aluminum shells in water. The eigenvibrations of the shell appear as resonances in the scattering amplitude of each normal mode; these are superimposed on a smooth background which if the shell is made thinner, converts from the amplitude of a rigid to that of a soft cylinder. The resonances themselves are exhibited by subtracting the background from the total amplitude and are seen to become less numerous as the shell gets thinner.

ISSN:0001-4966    

DOI:10.1121/1.381992

出版商:Acoustical Society of America    

年代:1978

数据来源: AIP

摘要:

A new approach to the guinea pig auditory nerve is presented. This approach, which has several advantages over previous methods, enables stable recordings from primary nerve fibers to be made. Entry to the auditory nerve is through the modiolus via scala tympani of the basal turn of the cochlea.

ISSN:0001-4966    

DOI:10.1121/1.381993

出版商:Acoustical Society of America    

年代:1978

数据来源: AIP

摘要:

This note reports some measurements of the changes in identification performance that result from presenting a fixed standard before each trial. These measurements indicate that the presence of the standard improves perfromance for test stimuli in the vicinity of the standard, except when the standard is near the extremes of the stimulus range.

ISSN:0001-4966    

DOI:10.1121/1.381994

出版商:Acoustical Society of America    

年代:1978

数据来源: AIP

摘要:

An attempt was made to extend the auditory localization model of Searle, Braida, Davis, and Colburn [J. Acoust. Soc. Am. 60, 1164–1175 (1976)] to regions beyond the frontal horizontal plane. On the basis of two experiments, it appears that the assumption of acuity independent of angle is not valid for these more extensive regions, although the distribution of error magnitude can be accounted for by a span‐specific unitary acuity. However, the assertion by the same authors that acuity is partially determined by the angular size of the speaker span was substantiated by direct experimental test. The results confirm the initial suggestion of Searleetal. that a complete account of the sound localization process must include both span and angular dependencies of acuity, and indicate average error to be a promising measurement technique in resolving this particular problem.

ISSN:0001-4966    

DOI:10.1121/1.381995

出版商:Acoustical Society of America    

年代:1978

数据来源: AIP

摘要:

Data on ultrasound velocity, compressibility, and specific acoustic impedance in bovine aorta, pulmonary artery, vena cava, and myocardium are reported and analyzed based on amounts of structural proteins present in these tissues.

ISSN:0001-4966    

DOI:10.1121/1.381996

出版商:Acoustical Society of America    

年代:1978

数据来源: AIP

摘要:

The equations of motion of the electret foil transducer are derived by applying Lagrange’s equation to the total electrical and mechanical energies of the transducer system. The resulting equations apply for the operation of the transducer both as a sound source and as a sound pickup. An expression for the induced static surface‐charge density on the back plate is obtained from these equations modified for the quiescent state. An electrical circuit model of the transducer is given for linear operation.

ISSN:0001-4966    

DOI:10.1121/1.381997

出版商:Acoustical Society of America    

年代:1978

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.2033214

出版商:Acoustical Society of America    

年代:1978

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.2033217

出版商:Acoustical Society of America    

年代:1978

数据来源: AIP