摘要:

A model for the subjective lateral position of 500‐Hz tones is presented and compared with experimental lateralization data. Previous papers in this series have explicitly described the auditory‐nerve response to these stimuli and proposed a binaural displayer that interaurally compares the auditory‐nerve firing times. The outputs of the displayer are postulated to represent the only information about detailed firing times that is available to the brain. In the present paper, lateral‐position predictions are obtained by a central nonoptimal weighting of these outputs that depends on the interaural intensity difference of the tone. These predictions describe the results of lateralization‐matching experiments more accurately and over a wider range of stimulus conditions than previous theories, except for those results which suggest that low‐frequency binaural tones can generate multiple perceptual images. The predictions of our model are also consistent with the results of centering and laterality‐comparison experiments. It is argued that the data discussed in this paper are generally incompatible with theories that propose a peripheral interaction of interaural timing and intensity information such as the latency hypothesis.

ISSN:0001-4966    

DOI:10.1121/1.381978

出版商:Acoustical Society of America    

年代:1978

数据来源: AIP

摘要:

Band‐limiting experiments were performed at three noise spectrum levels (N0=25, 40, and 55 dB SPL) for forward, simultaneous, and backward masking. Threshold for a 2‐kHz sinusoid decreased for masker bandwidths greater than a ’’critical bandwidth’’ in nonsimultaneous masking. These results are evidence for a suppression effect not observed in simultaneous masking; however, a qualitative model of suppression can account for the results in all three types of masking. In addition, the data for simultaneous masking support Fletcher’s [Rev. Mod. Phys. 12, 47–61 (1940)] rectangular filter interpretation of the band‐limiting experiment and are well described by a level‐dependent critical band.

ISSN:0001-4966    

DOI:10.1121/1.381979

出版商:Acoustical Society of America    

年代:1978

数据来源: AIP

摘要:

Comparisons were made for two species (chinchilla and mongolian gerbil) among mean behavioral audiogram, mean just detectable action potential (AP) responses to tone bursts, and single‐fiber response thresholds at the characteristic frequency, averaged in one‐octave bands. In normal animals and in a group of Kanamycin‐treated chinchillas, these mean measures appear to have a well‐ordered relationship. Unit and AP thresholds are within 10 dB from one another throughout the frequency range. Behavioral thresholds are usually 15–20 dB more sensitive, but the three curves are roughly parallel except at the highest frequencies, where the behavioral threshold begins to increase approximately one‐half octave above the physiological ones. Individual examples for four gerbils and four chinchillas having hair cell losses due to Kanamycin intoxication reinforce the notion based on mean data that in most cases AP thresholds can serve to predict the behavioral threshold configuration.

ISSN:0001-4966    

DOI:10.1121/1.381980

出版商:Acoustical Society of America    

年代:1978

数据来源: AIP

摘要:

A set of experiments was conducted using the Mössbauer effect to determine the vibratory characteristics of the basilar membrane, Reissner’s membrane, the malleus, incus, and oval window in squirrel monkey. A few measurements were also made in guinea pig in the basal cochlear region. The nonlinear vibration properties of the basilar membrane are described in detail for the midfrequency region in the squirrel monkey. Only in this region have nonlinear effects been observed. A comparison of mechanical and neural data indicates good qualitative agreement.

ISSN:0001-4966    

DOI:10.1121/1.381981

出版商:Acoustical Society of America    

年代:1978

数据来源: AIP

摘要:

The Bayes optimal detector is derived for a class of linear‐period‐modulated (LPM) signals whose velocities and times of arrival are uncertain. All terms necessary for claculating theaposterioriprobability‐density function of the uncertain parameters are shown to be available as a natural by‐product of the optimal detector computations. The processor structure derived is general in thataprioriknowledge of velocity and time of arrival other than complete uncertainty can be taken into account.

ISSN:0001-4966    

DOI:10.1121/1.381982

出版商:Acoustical Society of America    

年代:1978

数据来源: AIP

摘要:

A rigorous theoretical model is derived and used to calculate reverberation time of a room in terms of impedance of absorption materials on the wall and geometrical factors associated with such materials and the room. In addition, the reverberation time also depends upon the initial state of the pressure field before decay begins as well as on the single measure of pressure, for example spatial root mean square, used to characterize the decay‐time history. The theoretical model, which consists of a system of harmonic oscillators with damping provided through the wall impedance, is sufficiently general to take into acount all of these factors. Numerical examples are given to illustrate the procedure. A brief review of other methods for calculation of reverberation time is given, including a discussion of random and normal absorption coefficients.

ISSN:0001-4966    

DOI:10.1121/1.381983

出版商:Acoustical Society of America    

年代:1978

数据来源: AIP

摘要:

The noise‐induced permanent threshold shift (NIPTS) resulting form up to ten years of exposure to an averageA‐weighted sound levelLeqof 89 dB was investigated. Prior occupational noise exposure was controlled for by eliminating subjects with previous high‐noise‐level jobs or uncertain exposure histories. The final population consisted of 42 males and 58 females working in steady‐state broadband noise environments. No attempt was made to screen subjects for any auditory pathology. A 222‐subject control group from the same geographic area as the exposed subjects was selected such that none of its constituents had any effective industrial noise exposure. Presumed NIPTS was calculated by correcting each individual audiogram of the exposed subjects according to the aging curves developed from the control popultion hearing levels. The results indicated a considerable male–female difference in NIPTS, even though both groups were exposed to the sameLeq. Averaging the results for all 100 subjects, in order to make comparisons to other available data, yielded results in close agreement to predictions based upon the work of Burns and Robinson, Baughn, NIOSH, and Passchier–Vermeer, indicating that 10 years of exposure to a dailyLeqof 89 dB causes measurable hearing loss at 4 kHz.

ISSN:0001-4966    

DOI:10.1121/1.381984

出版商:Acoustical Society of America    

年代:1978

数据来源: AIP

摘要:

Most current knowledge about community response to noise exposure is derived from studies of high‐level transportation sources. A nationwide urban noise survey was undertaken to study effects associated with more moderate but far more common sorts of noise exposure. Over 2000 respondents at 24 sites in seven cities of varying noise exposure and population density were interviewed by telephone and in person about their reactions to everyday noises. A brief but comprehensive structured questionnaire was based on direct questioning about annoyance and related effects. Among the major findings of the survey were widespread annoyance and speech interference from exposure to urban noise and strong relationships between the extent of annoyance and exposure level, speech interference, and population density.

ISSN:0001-4966    

DOI:10.1121/1.381985

出版商:Acoustical Society of America    

年代:1978

数据来源: AIP

摘要:

In muffler design, concentric‐tube resonators are often used to provide high‐frequency attentuation. These resonators are constructed by shaping a rigid shell around a length of perforated tube, forming an unpartitioned cavity. Often the entire length of tube is perforated. Because of the length of the assembly, it is not possible to use the simple Helmholtz resonator theory to predict the attentuation. Beginning with a one‐dimensional control volume, a mathematical model was derived which accounted for mean flow in the tube and for the wave motion in the cavity and the coupling between cavity and tube via the impedance boundary of the perforate. For impedance in the linear regime, a closed‐form solution for the resonator transmission loss was obtained. With this restriction and for the case of zero mean flow, excellent agreement was obtained with experimental results. Limited parametric studies suggest that the performance of this type resonator is quite sensitive to the porosity of the perforate, and that unusually large bandwidths of attenuation may be obtained for select geometries at zero or near‐zero mean flow conditions. As mean flow is increased, however, the model suggest that such large bandwidths may not be attainable in practice.

ISSN:0001-4966    

DOI:10.1121/1.381963

出版商:Acoustical Society of America    

年代:1978

数据来源: AIP

摘要:

Young, middle‐aged, and old subjects, 35 in all, were tested to determine the probability of disturbance of sleep, as judged by EEG records, by seven noises per night produced by a recording of a passing truck. There is roughly a linear relation with theA‐weighted noise level. Young and old people have nearly the same response while middle‐aged subjects are more sensitive by about 15 dB. This applies also to the probability of awaking. The probability of shifts in sleep to a shallower level does not appear to adapt in 24 successive nights with seven noises per night but the probability of waking drops to half value in about two weeks. Response increases with duration of the stimulus, at least over the limited range from fractions of a second to a minute.

ISSN:0001-4966    

DOI:10.1121/1.381964

出版商:Acoustical Society of America    

年代:1978

数据来源: AIP