摘要:

Interaural correlation discrimination thresholds were obtained for auditory pulse trains. Pulse trains of random polarity or of random pulse occurrence were delivered to the two ears. The interaural correlation is defined by the pulse‐by‐pulse agreement between the ears. Coding by pulse occurrence and coding by pulse polarity are about equally effective, except for larger thresholds for polarity at low pulse frequencies. Thresholds for the discrimination of changes in positive interaural correlations are smaller than corresponding thresholds for negative correlations. Interaural correlation discrimination thresholds for pulse trains are comparable to those obtained with wide‐band continuous noise.

ISSN:0001-4966    

DOI:10.1121/1.1912484

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

The amplitude and the phase of vibration of the basilar membrane and the bony limbus of the cochlea were measured in living squirrel monkeys using the Mössbauer technique. In the middle ear, the vibration of the malleus (and occasionally the incus) was measured. The Mössbauer technique makes possible the measurement of very small velocities, e.g., 0.2 mm/sec. This sensitivity permits measurement of the motion of the malleus at sound‐pressure levels (SPLs) of 90 to 110 dB and measurement of the motion of the basilar membrane at 70 to 120 dB SPL, depending on the frequency. The basilar membrane vibrates nonlinearly for frequencies which produce the largest deflections at the spot on the basilar membrane under observation. The ratio of the displacement of the basilar membrane to that of the malleus was observed to have the following characteristics: (1) As the frequency is increased from a low value, its amplitude increases at 6 dB/oct until just below the maximum ratio where the slope increases to about 24 dB/oct; (2) the maximum ratio was about 24 dB for the SPLs used; (3) for frequencies above that producing the maximum ratio, the drop‐off rate was approximately 100 dB/oct; (4) the amplitude ratio did not drop off indefinitely but tended to level off; (5) the motion of the basilar membrane differs from the motion of the malleus by 90° at very low frequencies; (6) for frequencies below that producing the maximum ratio, the phase differences between the motion of the basilar membrane and that of the malleus is a linear function of frequency; (7) near the frequency corresponding to the maximum ratio, the phase difference decreases at a faster rate; and (8) the phase difference approaches a constant value (7π 8π or 9π) for high frequencies. Anatomical constraints allowed only a small portion of the basal turn to be studied (6.5–7.5 kHz produced maximum deflection of the basilar membrane in this region).

ISSN:0001-4966    

DOI:10.1121/1.1912485

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

It has been suggested that at very short durations, frequency spread of the signal is what determines the frequency resolving power of the auditory system. The validity of this notion is examined by applying a version of the “uncertainty principle,” which says that the product of “effective bandwidth” and “effective duration” is a constant that depends on the signal envelope. This bandwidth‐duration constraint permits several different envelopes to be used for the carrier signal in a frequency‐discrimination experiment, while at the same time restricting all the signals to the same nominal bandwidth. Rectangular, exponential, Gaussian, and gamma functions were used as envelope functions for a 1000‐Hz carrier. Parameter values were selected to equate the signal bandwidths to the bandwidth of a rectangular envelope signal, which had a duration ranging from 2 to 32 msec. The frequency‐discrimination data indicate that equating signal bandwidth in this way does not serve to make the signals equally discriminable. A more accurate way to estimate the discriminability for the different envelope sinusoids is to measure how long each signal envelope provides an acceptable signal‐to‐noise ratio.

ISSN:0001-4966    

DOI:10.1121/1.1912486

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

In a monaural detection with contralateral cue (MDCC) task, subjects detect a masked signal presented monaurally. A cue containing information relevant to the signal is presented to the other ear. We used a burst of noise as the signal and the same noise burst delayed or advanced by up to 2400 μsec as the cue. For most subjects, performance was best when the cue and signal were approximately simultaneous. When the cue led by about 800 μsec, performance dropped sharply to levels below those obtained without the cue, recovering to the uncued level for yet longer disparities. When the signal led the cue, performance dropped smoothly as a function of timing disparity, and for signal lead greater than about 1000 μsec, the cue had little effect on performance. Although the task subjectively is one of judging the apparent lateralization of the cue, we argue that the lateralization mechanism is not by itself the detecting mechanism.

ISSN:0001-4966    

DOI:10.1121/1.1912487

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

Monaural masked thresholds for clicks were established on three listeners. Masking functions across selected Δt's (the time disparities between the masker and click) were determined for four masking conditions in which the 70 dB SPL masker was a 500‐msec burst of random noise. These four conditions were (1) simultaneous masking, (2) forward masking (FM) at Δt's from 1 to 250 msec, (3) backward masking (BM) at Δt's from −1 to −250 msec, and (4) forward‐backward masking at selected Δt's between two 500‐msec noise bursts. In this last instance, the interval between bursts was varied to achieve seven interburst intervals (IBIs) ranging from 25 to 500 msec. Simultaneous masking was 3–5 dB less at the boundaries of the noise burst than it was in the middle of the noise burst. The functions for FM and for BM were not inversely symmetrical with one another, although both showed less threshold shift (TS) the further displaced in time the click was from the masker. The masking that appeared when the click was presented between two noise bursts was greater immediately adjacent to a noise burst than near the center of the IBI. During the longer IBIs (500–300 msec), the configuration of masking was equivalent to that of FM followed by BM, with slight excess appearing only in the interval 20–40 msec before the second noise burst. The configurations of FM and BM were preserved during the shorter IBIs (200–50 msec), but the TSs were greater than either type would have produced if operating alone. These TSs became larger as the IBI was shortened, so that the brief IBIs were permeated with large amounts of masking even in the middle of the IBI. This cumulation of masking was so great when the IBI was reduced to 25 msec that the masking function lost the configuration characterizing the longer IBIs. The TSs during shorter IBIs exceeded the sum of the residual effective powers of FM and BM.

ISSN:0001-4966    

DOI:10.1121/1.1912488

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

Sinusoidal vibrations are induced in a violin by an electromechanical transducer. An optical sensor is used to measure the amplitude and phase of vibration at various locations on the body of the violin. Frequency‐response curves for amplitude and phase are measured at 35 locations. These are fitted by a modified least‐squares method to the theoretically expected response curves, which are expressible in terms of dissipative eigenmodes. Of the eight most prominent eigenmodes, as isolated numerically, seven show a nearly standing‐wave character. For four of the seven, this standing‐wave character is not clear in the unprocessed data.

ISSN:0001-4966    

DOI:10.1121/1.1912489

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

Speech samples of five patients with cancer of the vocal folds and five individually matched normal speakers were analyzed with respect to: (1) maximum rate of change of fundamental frequency, (2) fundamental‐frequency perturbations related to specific consonants, (3) two perturbation factors, and (4) frequency distribution of fundamental frequency. It was found that most of these measures differentiated the pathological and normal speakers. The reliability and possible usefulness of each measure for detecting laryngeal cancer are discussed.

ISSN:0001-4966    

DOI:10.1121/1.1912490

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

Speech samples of 50 adult male speakers were presented to 22 listeners, who estimated the age of each speaker and rated the adequacy, hoarseness, harshness, and breathiness of his voice. Five of the speakers were patients with cancer of the vocal folds, and five were individually matched normal speakers. It was found that the judgments of age, adequacy, and voice quality were reliable and that they differentiated the pathological and normal speakers. The relationships among chronological age and the judgments of age, adequacy, and voice quality were examined.

ISSN:0001-4966    

DOI:10.1121/1.1912491

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

A digit recognition system based on simple segmentation rules according to articulatory features is described. The digits are segmented according to manner of articulation, and the first two formants are automatically tracked for vowel‐like segments. Each digit is represented by a sequence of segments and five formant values, namely, the first and second formant at the beginning and the end of the segment and the maximum value of the first formant within the segment. Reference patterns are established and unknown utterances are matched against them. Error rates range from 1.2% to 5.0%, and reject rates range from 1.1% to 4.4% for different experiments.

ISSN:0001-4966    

DOI:10.1121/1.1912492

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

The present paper compares four methods for measuring the speech‐quality parameter preference. The scales of the isopreference method, the category judgment method, the relative preference method, and the absolute preference judgment method (a proposed modification of the category judgment method) are related to a “preference unit” scale. Capabilities and performance of the methods are discussed and illustrated by evaluating a set of test signals with different types of degradation containing a subset of clearly discriminable signals. The paper tries to show how far preference results gained with one method allow prediction of corresponding results in terms of another method. Because of the quantitative limitations of subjective tests and especially since the four methods use different approaches and have different application ranges, it is not unexpected that the preference unit scale has been found to be more of scientific rather than of practical engineering interest. Listeners have been found capable of discriminating reliably, even without reference or anchor signals, more than the five quality steps provided by the category judgment method, and somehow also by the relative preference method. The proposed absolute preference judgment method recognizes this finding and, therefore, yields much better agreement with the isopreference method than the two other methods, which are apparently too strongly quantized.

ISSN:0001-4966    

DOI:10.1121/1.1912493

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP