摘要:

Fifty samples of noise waveforms (N) and 50 samples of signal‐plus‐noise waveforms (SN) were rated on 10 occasions by four listeners. The listeners decided whether the waveform was N or SN, and rated the degree to which the waveform had the N or SN quality. The signal was a 1‐kHz tone 500 msec in duration. Both signal and noise were gated. The results indicate greater reliability for ratings of SN waveforms than for ratings of N waveforms. Further, the results suggest that listeners can be quite consistent in rating some waveforms, but still not agree with each other.

ISSN:0001-4966    

DOI:10.1121/1.1912369

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

Temporary threshold shift (TTS) is generally believed to grow during noise exposure and recover afterwards in proportion to the logarithm of time. However, these logarithmic laws of TTS disagree with experimental observations made very early or very late in these processes. Better agreement with experiment is obtained if TTS is regarded as the sum of two components that vary exponentially with time. Published information on TTS was analyzed to determine the properties of these two components. Only one of the components is believed to be associated with permanent hearing loss resulting from noise exposure, and its simple electrical analog makes possible the construction of a TTS meter for appraising noise hazard. The analysis also revealed two other components of TTS that account for the “bounce” sometimes observed very early in the recovery process. Additional studies are needed to refine the theory and improve understanding of the auditory process.

ISSN:0001-4966    

DOI:10.1121/1.1912370

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

An experiment is reported that employed 20 normally hearing listeners who demonstrated an ability to concentrate on an interrupted signal that alternated with a shorter, more intense signal. The purpose of the study was to investigate the effects of the frequency relationship between the two components, to determine the effect of angular separation of the two components, and to demonstrate continuity effects in a free field. The results indicated a definite frequency effect and a significant though small effect due to angular separation on the continiuty threshold.

ISSN:0001-4966    

DOI:10.1121/1.1912371

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

Pitch memory for one and for two successive tones was examined in two experiments which employed a method of adjustment procedure (Expt. I) and a recognition (four‐alternative‐forced choice) task (Expt. II). Frequency ratio of the two‐tone targets was either simple (a musical third or fifth) or complex. Time between target and comparison tone(s) was either silent or filled with two intervening tones. The memory difference limen (DL) for each of two tones is about 1.5 to 2.0 times larger than the DL for one tone. The DL for pairs of tones with complex frequency ratios is, under some circumstances, larger than for pairs of tones with simple ratios. For “good pitch discriminators,” the task must become more difficult before ratio complexity affects performance than is true for “poor pitch discriminators.” At least two skill components, frequency analyzing power and memory, are present in these tasks, and consistent individual differences occur for both.

ISSN:0001-4966    

DOI:10.1121/1.1912372

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

The threshold of the acoustic stapedius reflex in man was investigated by means of changes in acoustic impedance of the ear. The contralateral ear was stimulated by using bands of noise and complex tones with various bandwidths. The experiments showed that the reflex threshold, expressed in decibelsre2.10−6N/m2, is almost constant for bandwidths less than a specific value and designated as “critical bandwidth.” When the bandwidth was further increased, a decrease in the reflex threshold at approximately 3–6 dB/oct was observed. Assuming that the stapedius reflex mechanism is loudness governed in persons with normal hearing, these findings confirm the existence of a critical bandwidth in loudness summation. In addition, the findings indicate that the basis for the critical‐band mechanism is located in the peripheral part of the auditory system, probably in the cochlea.

ISSN:0001-4966    

DOI:10.1121/1.1912373

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

Observers were asked to discriminate between a pair of 10‐μsec pulses and a single 20‐μsec pulse having the same total energy. The independent variable was the time, ΔT, between the two 10‐μsec pulses. The stimuli were also presented as elements in a periodic pulse train. The ΔTrequired for resolution of two clicks (two‐click threshold) was 10 μsec. Whereas the addition of a steady background noise produced a remarkably small change in the magnitude of the two‐click threshold, performance deteriorated markedly when the pulses were low‐pass filtered. It appears that discrimination of slight changes in the energy spectrum of the two transient signals, especially in the high‐frequency region (8000 Hz and above), underlies the ear's sensitivity to a temporal discontinuity.

ISSN:0001-4966    

DOI:10.1121/1.1912374

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

During the past decade a number of variations in the simple up‐down procedure have been used in psychoacoustic testing. A broad class of these methods is described with due emphasis on the related problems of parameter estimation and the efficient placing of observations. The advantages of up‐down methods are many, including simplicity, high efficiency, robustness, small‐sample reliability, and relative freedom from restrictive assumptions. Several applications of these procedures in psychoacoustics are described, including examples where conventional techniques are inapplicable.

ISSN:0001-4966    

DOI:10.1121/1.1912375

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

Two methods are described for determination of the microphonic generator transfer characteristic using data from bitonal stimulation experiments. In one method, the filtered high‐frequency microphonic output component is measured at the extreme points of the modulation envelope for a sequence of intensity levels of the lower‐frequency component. This method is applied to data derived from a modulation test procedure making use of a wide range of test intensities for both the high‐ and low‐frequency components and also to data generated in a test using a single sequence of stimuli with increasing intensity of the lower frequency. In a second method, the modulation envelope of the higher‐frequency microphonic response to a bifrequency acoustic stimulus is used to determine a segment of the generator transfer characteristic. The results of a sequence of determinations for different lower‐frequency intensities show good agreement with each other and with the transfer characteristic derived by the first method. However, the second method shows that there is an appreciable level‐dependent hysteresis, the mechanism for which has not been determined. The transfer characteristics determined would give rise to a pronounced dc rectification component in the direction of positive summating potential.

ISSN:0001-4966    

DOI:10.1121/1.1912376

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

Perception of auditory patterns based on an intensity difference was tested in 30 normal subjects under binaural, monaural, and dichotic listening conditions. Each auditory pattern was made up of three temporally spaced white‐noise bursts involving two elements, i.e., “Soft” (S) and “Loud” (L). Patterns included SLS, LSL, LLS, SSL, LSS, and SLL. The loud element in the patterns remained at a constant intensity throughout, with the soft elements attenuated from 5 to 20 dB in different sets of patterns. Patterns were presented at 50 dB SL. Subjects needed a 10‐dB intensity difference within a pattern in order to recognize it correctly half the time, although the just noticeable difference (jnd) for white noise is about 0.5 dB. This seems to indicate that the pattern recognition task is a higher auditory function than simple discrimination of intensity differences. An unexpected finding was a large number of complete pattern reversals or mirror images which accounted for 30%–40% of errors across listening conditions and intensity‐difference levels. Symmetrical patterns were more commonly reversed than asymmetrical patterns. It is suggested that reversals of auditory patterns may occur in a manner similar to figure and ground reversal in vision.

ISSN:0001-4966    

DOI:10.1121/1.1912377

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

This study investigated the effects of four levels of broad‐band noise [40‐, 60‐, 80‐, and 100‐dB sensation level (SL)], presented to the contralateral ear, on the loudness of a monaurally presented 1000‐Hz pure tone. Loudness functions were obtained with the method of numerical magnitude balance. The findings indicate that when monaural loudness functions for a 1000‐Hz pure tone, obtained with contralateral noise present, are compared with monaural loudness functions for a 1000‐Hz pure tone, presented in quiet, there is a loss of loudness at low sensation levels, a loudness increase of as much as threefold at moderate SLs, and approximately equal loudness at high SLs. The loudness at lower SLs appears to be inversely related to the intensity of the broad‐band contralateral noise, and the loudness at moderate SLs appears to be directly related to the intensity of the broad‐band contralateral noise.

ISSN:0001-4966    

DOI:10.1121/1.1912378

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP