摘要:

An improved technique has been developed for studies of the shear viscosity of fluids. It utilizes an acoustic resonator as a four‐terminal electrical device; the resonator’s amplitude response may be determined directly and simply related to the fluid’s viscosity. The use of this technique is discussed briefly and data obtained in several fluids is presented.Subject Classification: [43]35.10, [43]35.68; [43]85.52.

ISSN:0001-4966    

DOI:10.1121/1.381124

出版商:Acoustical Society of America    

年代:1976

数据来源: AIP

摘要:

The problem of the excitation, detection, and scattering of electroelastic surface (Bleustein) waves is solved exactly by determining the charge distribution on the fingers of an interdigital transducer. The approach is to solve an integral equation, in the Fourier transform domain, that relates the charge density on the fingers to the electric potential of the fingers. The solution of the integral equation is accomplished by expanding the charge distribution in a series of pulses and then transforming the problem to a vector matrix,one which is readily handled by a computer. In this manner the charge distribution is determined for a variety of conditions.Subject Classification: [43]35,54.

ISSN:0001-4966    

DOI:10.1121/1.381125

出版商:Acoustical Society of America    

年代:1976

数据来源: AIP

摘要:

The dissipation in an elastic medium is represented by a dissipation mechanism which is similar to one used in an earlier paper [M. Caputo, Geophys. J. R. Astron. Soc. 13, 529–539 (1967)], but is simpler and has a frequency‐independentQ−1. The vibrations of a plate are studied by obtaining the eigenfrequencies, the amplitude of the displacement, the dispersion relation, theQ−1, the hysteresis cycle, and the yield stress.Subject Classification: [43]40.24.

ISSN:0001-4966    

DOI:10.1121/1.381126

出版商:Acoustical Society of America    

年代:1976

数据来源: AIP

摘要:

This paper presents an analysis of the free vibrations of a disk–cable system spinning freely about a fixed axis through the disk center. Secondly, it is shown how the cable can be used as a vibration absorber to reduce the effect of torsional disturbances on a rotating system.Subject Classification: [43]40.22, [43]40.70.

ISSN:0001-4966    

DOI:10.1121/1.381127

出版商:Acoustical Society of America    

年代:1976

数据来源: AIP

摘要:

The current method of measuring impact noise transmission involves the use of a standard hammer machine to produce a series of impact on the floor‐ceiling structure, and the measurement of the resulting noise produced in the room below. The method has been criticized on the ground that ratings based on the test data correlate poorly with the subjective judgments of people listening to real‐life impacts on the same floors. An alternative test method is proposed that uses a modified hammer machine whose internal impedance, intensity of impact, and striking frequency simulate those of real footfalls. The new method involves several changes from the present standard: short‐term rms impact sound levels are measured instead of long‐term rms levels; no normalization for the sound absorption of the receiving room is required; since the short‐term levels are higher than the long‐term levels usually measured, background noise is less of a problem than for the existing method. These proposed changes based on recent studies are expected to improve the correlation between test data and subjective judgments of floors.Subject Classification: [43]55.80; [43]50.45.

ISSN:0001-4966    

DOI:10.1121/1.381135

出版商:Acoustical Society of America    

年代:1976

数据来源: AIP

摘要:

Measurements of the microphonic potential from the lateral line sensory organs of killifish (Fundulusheteroclitus) are presented in this report. The potential consists of a dc shift and a dominant oscillatory component at twice the frequency of the stimulus, and it grows with the square of the stimulus at low amplitudes. An electrical circuit model of the microphonic is developed, assuming a simple quadratic nonlinearity in the electrical response of an individual hair cell as suggested by Flock. The model allows investigation of variable conductive or variable capacitive effects in microphonic generation, and the results obtained from the model are compared to the observed properties of the microphonic potentials. It is concluded that hair cell microphonics appear to be generated by a process involving current flow through a variable conductance, although capacitive effects of the hair cell are important in determining the waveform of the microphonic and its behavior as a function of frequency. A discrepancy between the observed low‐amplitude growth of the microphonic in killifish and the reported low‐amplitude growth of the microphonic in other acoustico‐lateralis preparations is also discussed.Subject Classification: [43]65.28, [43]65.20, [43]65.40.

ISSN:0001-4966    

DOI:10.1121/1.381136

出版商:Acoustical Society of America    

年代:1976

数据来源: AIP

摘要:

An interferometric optical heterodyne technique has been developed especially for vibrational amplitude and phase measurements on auditory organs of live animals. Laser light diffusely scattered from the vibrating structure is used for the measurement. Continuous calibration and feedback compensation systems were developed to cope with the problems of drift in interferometer alignment and small background movements. Vibrational amplitudes from below 0.1 Å to above 400 Å have been detected on the posterior tympanic membranes of live crickets.Subject Classification: [43]65.20; [43]40.60; [43]35.65.

ISSN:0001-4966    

DOI:10.1121/1.381137

出版商:Acoustical Society of America    

年代:1976

数据来源: AIP

摘要:

Loudness growth at 1000 and 3000 Hz was measured directly by magnitude estimation and production, and indirectly by loudness matches between tone and wide‐band noise and by interfrequency matching. The outcome of the three series of experiments does not reveal any systematic difference in shape of the loudness curves at 1000 and 3000 Hz. To a first approximation, above about 30 dB SL the loudness functions at 1000 and 3000 Hz are power functions of sound pressure with an exponent close to the accepted ISO standard of 0.60 (0.30resound intensity). Below 30 dB SL both loudness curves become progressively steeper than a simple power function and approach the same limiting slope,resound intensity, of unity. Consistent with Steven’s calculation system [J. Acoust. Soc. Am. 51, 575–601 (1972)], the data also show that loudness equality is achieved when a 3000‐Hz tone is about 8 dB below the SPL of a tone at 1000 Hz.Subject Classification: [43]65.50, [43]65.75.

ISSN:0001-4966    

DOI:10.1121/1.381138

出版商:Acoustical Society of America    

年代:1976

数据来源: AIP

摘要:

The identification of specific random waveforms, imbedded within random interference, was examined. Backward interference (interference after the specific waveform) was more effective than forward interference (interference before the specific waveforms). The accuracy of identification with combined interference (interference before and after the specific waveforms) is approximated by an independence model of interference. Under the present test conditions, interference with the identification of specific random waveforms is interpreted to be more nearly related to the interruption of auditory processing than to the masking of signal audibility.Subject Classification: [43]65.58, [43]65.75, [43]65.52.

ISSN:0001-4966    

DOI:10.1121/1.381139

出版商:Acoustical Society of America    

年代:1976

数据来源: AIP

摘要:

Old World monkeys were trained with an operant conditioning technique to discriminate the natural speech sounds /ba/–/da/ and transferred to synthetic speech. Human and monkey difference thresholds for formant transitions were then compared along a seven‐step /ba/–/da/ continuum. Monkeys were not as sensitive as humans to differences in formant transition: the just noticeable difference for monkeys was about 320 Hz, and for humans, about 160 Hz. Although humans were more adept at intraphonemic discriminations than monkeys, their latencies to stimulus changes revealed evidence of ’’categorical perception’’ of the continuum: While latencies for the monkeys increased linearly as stimulus difference was decreased, human latencies were essentially constant for all interphonemic comparisons, but increased sharply for intraphonemic comparisons. We view these data as evidence for (a) similar sensory capacities in monkeys and humans, but (b) unique speech processing capacities in humans.Subject Classification: [43]65.75; [43]70.30; [43]80.50.

ISSN:0001-4966    

DOI:10.1121/1.381140

出版商:Acoustical Society of America    

年代:1976

数据来源: AIP