摘要:

Period histograms, which display the distribution of spikes throughout the period of a periodic stimulus, were computed for discharges recorded from single auditory nerve fibers of the squirrel monkey when low‐frequency tones were employed. For frequencies up to about 4 kHz, where phase locking is observed, the average phase angle of the discharges was tracked as frequency was varied in small steps from low to high. To a first approximation, the cumulative shift in average phase angle is a linear function of frequency as would be observed for an ideal delay line. The slopes of these phase‐versus‐frequency lines were found to be related through a power law to the best frequencies of the fibers. Thus, it seems possible to estimate the travel time of a mechanical disturbance between the oval window and any point on the cochlear partition. A more detailed examination revealed that average phase angle is also sensitive to intensity, depending upon the relation of the stimulating frequency to the best frequency. For stimulating frequencies below best frequency, discharges tend to occur progressively later in the cycle as intensity increases. Above best frequency, an opposite tendency often prevails if a change in phase angle occurs. At or near best frequency, little change in average phase angle is noted as intensity varies.

ISSN:0001-4966    

DOI:10.1121/1.1912474

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

A correlation between the behavior of the interscala cochlear‐microphonic phase and the absolute phase shift between microphonic and sound at the eardrum is presented. It is shown that absolute phase can be interpreted with confidence over a limited frequency region for a given electrode location. Within this region the travel time in the cochlea, as manifested by microphonic measurements, is frequency independent.

ISSN:0001-4966    

DOI:10.1121/1.1912475

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

The interelectrode phase and the relative microphonic magnitude have been measured from electrodes placed in scalae vestibuli and tympani of the first three turns of the guinea pig cochlea. The relative phase difference between two electrodes in a given turn appears to be a sensitive indicator of the contributions to the recorded microphonics of local and remote potential generators. It is suggested that in the guinea pig, local responses can be measured up to 10 000 Hz in the first turn, up to 3000 Hz in the second turn, and only up to 500 Hz in the third turn. The results of interaction between local and remote activity, as manifested in amplitude and phase patterns of the microphonic, are demonstrated in detail and the influence of stimulus intensity is treated. Attention is called to some of the pitfalls that result from drawing inferences from data that are obtained in a frequency region where the response is dominated by remote components. Finally, for comparison, interelectrode phase data are given for the first turn of the cat's cochlea, and the problems of recording from the round‐window region are considered for both cat and guinea pig.

ISSN:0001-4966    

DOI:10.1121/1.1912476

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

In a previous paper the audibility has been reported of high harmonics which had been eliminated from the spectrum of a periodic pulse. The present paper gives evidence that this phenomenon can be ascribed to an analysis of the time pattern of the stimulus. This time analysis is thought to occur after a frequency analysis with limited resolving power, such as is carried out at the basilar membrane. Evidence for this idea is provided by a scanning experiment. The response to a periodic pulse is scanned with a periodic sine‐wave train as a probe. The data show a distinct time effect. A simple model of the peripheral auditory system (a bank of bandpass filters followed by time selective energy detectors) is shown to describe the data qualitatively. A quantative description requires additional specifications of the filter and detector characteristics. This allows an estimation of the frequency resolving power of the peripheral auditory system. For the quality factorQ, we thus estimated a value greater than 7.

ISSN:0001-4966    

DOI:10.1121/1.1912477

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

A study was done to investigate lateral asymmetries in the perception of dichotic synthetic verbal stimuli in a group of 24 normal‐hearing right‐handed subjects. The subjects were tested under the following reporting conditions: (1)free recall, in which the subject reported the stimuli in any order; (2)ordered before, in which the subject was instructed which ear to report first before the presentation of stimuli; and (3)ordered after, in which the subject was instructed which ear to report first after the presentation of the stimuli. It was found that a significant right‐ear preference for dichotically presented verbal stimuli existed regardless of the report strategy employed. In all three reporting conditions, the right ear showed a significant superiority of accuracy of response.

ISSN:0001-4966    

DOI:10.1121/1.1912478

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

By employing the same narrow band of noise (50 Hz wide, centered at 500 Hz) as both masker and signal, and by introducing a phase‐shifting network between the masking and signal channels, it is possible to control the phase angle, α, between the two. For a given signal‐to‐noise ratio, controlling the phase angle, α, controls the relative magnitudes of the interaural phase (time) difference and the interaural difference in level between the stimuli at the two ears. When α lies between 0° and 90° and the signal is reversed at one ear relative to the other (N0Sπ), the interaural time difference and the interaural level difference favor the same ear. However, when α is between 90° and 180°, the ear that leads in phase or time will receive the weaker stimulus, thus putting time and intensity into opposition as cues to the lateralization of the stimulus. Data on both detection and lateralization were obtained using the single‐interval forced‐choice procedure. Large masking‐level differences were found at all values of α, and good detection was exhibited even at those values of α where time and intensity were in opposition, and where performance in lateralization was very poor. Substantial individual differences in the relative importance of time and intensity as cues were found among the subjects.

ISSN:0001-4966    

DOI:10.1121/1.1912479

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

The detectability of brief, 1000‐Hz sinusoids added in phase or in quadrature to a continuous tonal masker (pedestal) of the same frequency as the signal was examined in the presence of a continuous wide‐band noise. The effects of signal duration, shape of the signal's energy‐density spectrum, sound‐pressure level (SPL) of the pedestal, and noise spectrum level were investigated. For conditions in which the background noise level was low, two unusual phenomena were noted: (1) a complete absence of the customary trading relation between signal power and duration; and (2) an extremely shallow masking function relating signal SPL and pedestal level. These departures from the law of temporal integration and Weber's law are consistent with a simple filter model of the ear in which it is assumed that the location of the auditory filter is altered in response to changes in the parameters of the signal and masker. A basic assumption of the model is that the location of the filter is changed in order to maximize the ratio of signal energy to masker energy at the output of the filter. For detection of a tonal signal in the presence of another sinusoid, it appears that observers can listen at frequencies far removed from that of the signal, where signal energy is as much as 40 dB down from the peak.

ISSN:0001-4966    

DOI:10.1121/1.1912480

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

On different blocks of trials, subjects were asked either to detect or to lateralize a monaurally presented signal (Sm) in a binaurally presented noise masker (NO). Eight values of signal duration, ranging from 50 to 800 msec, were used for both detection and lateralization. The psychometric functions for lateralization and those for detection differed in form, but, despite this difference, both were displaced toward greater signal levels at about the same rate as signal duration decreased. That is, the difference between lateralization and detection was approximately the same for all signal durations. Signal: 400 cps. Masker: wide‐band noise, 45 dB SPL/cycle. Method: single‐interval forced choice.

ISSN:0001-4966    

DOI:10.1121/1.1912481

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

This investigation was designed to explore the relationships between postexposure temporary threshold shift (TTS) and postexposure temporary loudness shift (TLS) when both measures were obtained under similar experimental conditions. A special paradigm was designed which could be adapted to measure either TTS or TLS. Three different measures of sensitivity (TTS, TLS with loudness balances made at the exposure level, and TLS with loudness balances made at a constant 30 dB SPL) were obtained on one ear of each of five normal‐hearing trained observers. The measures were obtained at 1000 and 1400 Hz by means of a Békésy‐type tracking procedure both before and following a 5‐min exposure to three different levels (50, 80, and 110 dB SPL) of a 1000‐Hz pure tone. Analysis of the results of the investigation indicated that when TLS is measured at a constant level (30 dB SPL), both its growth pattern and its recovery pattern are similar to those of TTS, but when TLS is measured at the same level to which the ear is exposed, its growth pattern and its recovery pattern are different from those of TTS.

ISSN:0001-4966    

DOI:10.1121/1.1912482

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

Auditory unmasking was studied in an experiment that used natural and synthetic vowel sounds as target signals. In all listening conditions, the spectrum level of the noise was constant and the noise was in phase at the two ears, while the interaural phase relations of the signals were manipulated. The results support the idea that maximal threshold shifts occur when the components of the complex signal in the 250‐ to 500‐Hz region are interaurally out of phase. However, the data do not support the idea that the magnitude of the unmasking is a simple function of fundamental frequency. Binaural unmasking of complex amplitude varying stimuli may be best accounted for by considering the amount of energy in the 250‐ to 500‐Hz band relative to the characteristic spectral maxima in the signal. Interaural phase inversions outside the 250‐ to 500‐Hz band have differential effects on unmasking depending upon the amplitude relations between the energy inside and outside this band.

ISSN:0001-4966    

DOI:10.1121/1.1912483

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP