摘要:

A parametric study of the ΔIjnd for the lateralization of transients (i.e., the smallest change in intensity of a transient at one ear required to displace a click image from some referent ΔIposition) was performed. Referent ΔI's were generated by presenting a click to one ear and a less intense click to the other ear. The ΔIjnd was determined by a further attenuation of the less intense click. The results indicate that click sensation level and the referent ΔIinteract in determining the ΔIjnd. These results do not conform with predictions made by the latency‐intensity conversion hypothesis, which has been advanced as a model for the lateralization of transients. An alternative model based on the premise that the ΔIjnd for the lateralization of transients is related to themonoticjnd for intensity was tested and confirmed.

ISSN:0001-4966    

DOI:10.1121/1.1911805

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

Thresholds of human hearing were obtained underwater at depths of 35, 70, and 105 ft. Subjects were six divers experienced in taking underwater hearing‐threshold tests by a modified Békésy technique. No significant effect resulting from the depth was noted. Threshold shifts (reair) for the three conditions of underwater hearing were consistent with those previously reported.

ISSN:0001-4966    

DOI:10.1121/1.1911806

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

The importance of data regarding the effect of short signal durations on detection for gated‐ versus continuous‐noise maskers and the theoretical implications of this data have been presented in recent papers by Jeffress, Tucker, and Williams. Masked thresholds for a 1000‐Hz signal of 40‐, 80, 160‐, and 400‐msec duration were determined in the presence of a narrow‐band masking noise that was either continuously on or gated only during the two possible signal intervals, with the masker presented over a 90‐dB range of levels. At the 400‐msec duration, the continuous masker led to thresholds that were about 2 dB lower than did the gated masker at all but the lowest masker levels. At shorter durations, consistent continuous‐gated differences in threshold were not found, indicating that, in addition to the experience of the listeners (as suggested by Tucker, Williams, and Jeffress), the level of the masker may also be a factor in the difference between continuous and gated masked thresholds or signal detectability.

ISSN:0001-4966    

DOI:10.1121/1.1911807

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

Monaural intelligibility functions for spondaic and monosyllabic words and identification functions for synthetic sentences were obtained for 14 experimental conditions of masking by random noise. The noise was presented continuously and interrupted or modulated (−14‐dB interburst ratio) at rates of 1, 10, and 100 interruptions per second. The intensity levels of the maskers were 50 and 90 dB SPL. Results demonstrated that (1) masking effectiveness decreased for spondees and sentences as the interruption rate decreased; (2) the greatest release from masking for monosyllabic words was found during the 10‐ips condition at favorableS/Nratios; however, at the more unfavorableS/Nratios, greater release from masking was observed during the 1‐ips condition; (3) greater release from masking occurred for interrupted than for comparable modulated noise conditions. The possible effects of the interaction between the type of speech material and forward and backward masking during thesilentinterval between noise bursts is discussed.

ISSN:0001-4966    

DOI:10.1121/1.1911808

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

Temporary threshold shift (TTS) and acoustic reflex activity were observed in 20 normal hearing subjects under several different states of attention. The Zwislocki acoustic bridge (model 3) was used to monitor acoustic reflex activity. Compliance shifts (changes in relative compliance) were measured during exposure of the contralateral ear to a 1000 Hz narrow‐band noise presented at 105 dB SPL, and TTS was measured at 1000 Hz for the contralateral ear after approximately412 minof noise exposure. These measures were taken under three different conditions or modes of attention as defined by task performance: reverie (no task performance, high auditory attention), intelligibility test, and high visual attention (visual‐motor task). Also, levels of attention, as operationally defined by levels of task performance, were considered. From the results of this and other investigations it was concluded that there is a so‐called central factor involved in acoustic reflex activity although task performanceper se, not type of task, is the important factor. However, such a factor in TTS, if observed, is probably an artifact of the type of task performance of the listener.

ISSN:0001-4966    

DOI:10.1121/1.1911809

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

Two experiments are reported that employed 10 normally hearing listeners who demonstrated an ability to concentrate on an interrupted white noise that alternated with a tonal burst. The purpose of the study was to demonstrate continuity effects in a free field situation and to investigate the effects of frequency and level of the signal component, the duration of the noise component, and the angular separation of the two components. The results showed that the level and the duration variables effected changes in continuity thresholds. Angular separation did not appreciably affect the perception of continuity in the noise.

ISSN:0001-4966    

DOI:10.1121/1.1911810

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

The contralateral remote masking (CRM) caused by a high‐frequency‐band noise is determined in the frequency range 250–1200 cps. The threshold shift expected from the mechanical changes due to the aural reflex is calculated on the basis of measurements of the acoustic impedance at the ear drum. The two sets of measurements are performed on seven subjects. The results support the assumption that central factors predominate in the CRM and that the middle‐ear muscles are responsible for a small part of the masking only.

ISSN:0001-4966    

DOI:10.1121/1.1911811

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

The interleaving peak structure of poststimulus time (PST) histograms of low‐frequency cochlear‐nerve‐fiber responses to acoustic clicks of both polarities implies that a cochlear neuron is excited by a damped oscillatory waveform, referred to here as a click excitation function (CEF) that is half wave rectified. For a stimulus consisting of two closely spaced clicks, the amplitude and delay of the second click relative to the first click can be adjusted so that one‐half cycle of the CEF due to the first click nulls or cancels a particular half‐cycle of the other CEF. A null produced in this manner can be detected from the PST histograms of responses of a particular fiber to both polarities of the click‐pair stimulus. This nulling technique has been used to study the responses of cochlear nerve fibers to combination click stimuli. Details of these measurements are given, and the interpretation of the results leads to the consideration of two apparently different nonlinear phenomena. These results and the techniques used to obtain them provide a means by which certain constraints on the mechanisms of the peripheral auditory system can be evaluated.

ISSN:0001-4966    

DOI:10.1121/1.1911812

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

The detectability of a brief 10‐msec sinusoidal signal was measured in the presence of a sinusoidal masker. The frequency of the masker was varied while the frequency of the signal was fixed at either 250, 1000, or 2800 Hz. In the first study, the masker was either continuous or gated; when gated, it was also 10 msec in duration and occurred simultaneously with the signal. When the masker was continuous, the data agreed essentially with those reported by Wegel and Lane in their classic paper. If the masker was gated and near the signal in frequency, there was little difference in the amount of masking produced by the gated and the continuous conditions, although gating the maskers produced somewhat more masking, about 5 dB. When the frequency of the signal and masker differed, for example, in the case of a masker at 1200 cps with a signal at 1000 cps, the gated condition produced substantially more masking, about 40 dB. A second study measured how the signal level must be changed to compensate for an increase or decrease in the masker level. In the third study, the signal was presented at various delays after the onset of the maskers to determine how long the masker must be present to achieve, effectively, a continuous‐masker condition.

ISSN:0001-4966    

DOI:10.1121/1.1911813

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

Fourteen young guinea pigs were individually exposed to 500 rounds of paper “caps” tired in a toy gun at a distance of 30 cm. The gun was fired at intervals of 1 5 sec. After seven weeks survival, the cochleas were removed and each complete organ of Corti examined, using Engström's surface‐preparation technique. Cochleograms (tabular forms showing position and condition of each cell) were prepared for each row of hair cells. Curves were plotted showing number of damaged cells as a function of distance from the base. In approximately 80% of the cases, total destruction of hair cells occurred in a narrow band midway along the organ of Corti. The severity and distribution of damage for the group are compared with similar data for another group, which was exposed to high‐intensity pure tones.

ISSN:0001-4966    

DOI:10.1121/1.1911814

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP