摘要:

A theoretical analysis of the propagation of pressure waves through elastic tubes filled with streaming incompressible viscous liquid is presented. The limiting results for the case of vanishing viscosity are compared with those for an inviscid liquid. The influence of the steady stream upon which waves are superposed, of wall inertia, and of Poisson's ratio are discussed. The analysis is restricted to tubes with thin walls, to waves whose amplitude is small and whose wavelength is large compared to the radius of the tube, and to liquids with sufficiently small viscosity.

ISSN:0001-4966    

DOI:10.1121/1.1908005

出版商:Acoustical Society of America    

年代:1955

数据来源: AIP

摘要:

A wave equation for the sound propagation through tubes is derived by means of Hamilton's variational principle. It is assumed that the wave fronts can be approximated by surfaces of constant stream potential; this is the only assumption made. The variational principle ensures that the best equation that is compatible with this assumption will be obtained. The equation has the form of Webster's horn equation, however its coefficients are defined differently.

ISSN:0001-4966    

DOI:10.1121/1.1908007

出版商:Acoustical Society of America    

年代:1955

数据来源: AIP

摘要:

This paper describes cemented barium titanate accelerometers of two simple types, an electromagnetic shaker with a symmetrically mounted shake table, a set of barium titanate shakers, and two optical methods of accelerometer calibration, one using a microscope with a stroboscope of wide frequency range and one using a Fizeau type interferometer. Calibration results from 50 to 11 000 cps are given.

ISSN:0001-4966    

DOI:10.1121/1.1908009

出版商:Acoustical Society of America    

年代:1955

数据来源: AIP

摘要:

A system consisting of specially designed pressure switches and a simple associated circuit is described for measuring the velocity of propagation of shock waves in tubes.

ISSN:0001-4966    

DOI:10.1121/1.1908011

出版商:Acoustical Society of America    

年代:1955

数据来源: AIP

摘要:

The loudness of a steady auditory stimulus declines during the first few minutes of the application of that stimulus. This decrease in loudness is so great that it is important to know whether or not the masked threshold also changes during the initial period of stimulation. In the present investigation the degree of perstimulatory fatigue and the amount of masking were both determined for the same stimulus. It is shown that the masked threshold is essentially independent of the duration of the masking stimulus.

ISSN:0001-4966    

DOI:10.1121/1.1908012

出版商:Acoustical Society of America    

年代:1955

数据来源: AIP

摘要:

When a fatiguing tone is presented to one ear of an observer, and, after a period of time, a comparison tone of the same frequency is also presented to the other ear, the intensity of an equally‐loud comparison tone is considerably less than the intensity of the fatiguing tone. This phenomenon has been referred to as perstimulatory fatigue. The present investigation was designed to determine the extent to which the perstimulatory fatigue induced by a pure tone spreads to neighboring frequencies.Perstimulatory fatigue was measured by means of a series of simultaneous dichotic loudness balances made prior to, during, and subsequent to stimulation by a fatiguing tone of 1000 cps at a SPL of 80 db. Test tones were the same in sound pressure as the fatiguing stimulus. When measuring fatigue at a frequency other than that of the fatiguing tone, the fatiguing stimulus was turned off for a 15‐second interval. During this interval, a loudness balance was made at the frequency of the test tone.The findings demonstrate that maximum fatigue is produced at the frequency of the fatiguing stimulus. Fatigue falls off rapidly on both sides of this frequency at a negatively accelerated rate until at 100 cps and at 2500 cps little or no effect is evident. The gradients of perstimulatory fatigue are nearly symmetrical when plotted on a log‐frequency scale.

ISSN:0001-4966    

DOI:10.1121/1.1908014

出版商:Acoustical Society of America    

年代:1955

数据来源: AIP

摘要:

An old and revived graphical method is applied to the hydraulic theory of cochlear mechanics.

ISSN:0001-4966    

DOI:10.1121/1.1908016

出版商:Acoustical Society of America    

年代:1955

数据来源: AIP

摘要:

The rise‐fall time, duty cycle, and carrier frequency of a pulsed tone were systematically varied. Listeners matched the pitch of this signal to that of a sinusoidal comparison tone. Low SPL was used throughout. Two pitches were identified, one corresponding to the repetition rate (periodicity pitch), and the other to the carrier frequency (carrier pitch). The periodicity pitch decreased in audibility with the increase of any of the experimental variables. These variables had the opposite effect on the perception of the carrier pitch, which in general was audible only at the longer duty cycles. Individual listeners varied considerably in their ability to match the pitch of the pulsed tones. Comparison of the results obtained with pulsed sinusoids to those of pulsed noise suggest that the perception of a periodicity pitch depends upon the band width and spectral location of the pulsed signal's frequency components as well as envelope wave form fluctuation.

ISSN:0001-4966    

DOI:10.1121/1.1908018

出版商:Acoustical Society of America    

年代:1955

数据来源: AIP

摘要:

This paper describes an investigation of the effect of sound duration on the perception of a linguistic characteristic, the recognition of phonemes. A pair of single syllable words was selected which consisted of identical phoneme sequences, except for the final phoneme which was either the voiced or unvoiced version of the same articulation. Different versions of these words were synthesized with all possible combinations of four different vowel durations and five different final consonant durations. In all cases the sound wave corresponding to the final consonant was inharmonic and identical except for duration. These synthesized words were recorded and presented to a group of 33 listeners who had to judge whether they heard the final consonant as a voiced or as an unvoiced sound. The results clearly show that the relative durations of vowel and final consonant can be used as a cue for hearing the final sound as voiced or unvoiced. This demonstrates that, in certain circumstances, nonspectral characteristics such as duration can serve as the basis for phoneme recognition. It also gives an example of a cue for sound recognition which, due to its relative nature, can be perceived only when it appears in a sequence of phonemes and not when the sound is pronounced in isolation.

ISSN:0001-4966    

DOI:10.1121/1.1908020

出版商:Acoustical Society of America    

年代:1955

数据来源: AIP

摘要:

The experiments reported in this paper are an attempt to explore the influence of certain physical cues on the perception of linguistic stress patterns. The material chosen was a group of English words in which a change of function from noun to verb is commonly associated with a shift of stress from the first to the second syllable. Spectrograms were used to determine the vowel duration and intensity ratios which occur in these words and this information was applied in making up a test in which listeners' judgments of stress could be correlated with variations in the duration and intensity ratios. The results of the experiments show that duration and intensity ratios are both cues for judgments of stress and that, in the material studied, duration ratio is a more effective cue than intensity ratio.

ISSN:0001-4966    

DOI:10.1121/1.1908022

出版商:Acoustical Society of America    

年代:1955

数据来源: AIP