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Journal of the Acoustical Society of America

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Dec 1971

Volume 50, Issue 6B, pp. 1475-1562


The Vibratory Pattern of the Round Window in Cats

Shyam M. Khanna and Juergen Tonndorf

J. Acoust. Soc. Am. Volume 50, Issue 6B, pp. 1475-1483 (1971); (9 pages) | Cited 1 time

Online Publication Date: 11 Aug 2005

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Round‐window displacements were recorded by means of time‐averaged holography in live cats and in fresh animal cadaver specimens. Considerable technical difficulties had to be overcome first, before such recordings became feasible. In the majority of cases, the displacement pattern was complex, even at low frequencies, with the maximum displacement occurring in the anterio‐superior region. Between‐animal variations were relatively large. From the reconstructions, volume displacements and eventually volume velocities were calculated for given frequencies. Since the sound pressures had been directly applied to the stapes footplate, the volume velocities for given sound‐pressure levels (SPLs) could be converted into inner‐ear impedance values, the assumption being that, for a given situation, volume displacements of the round window should equal those of the oval window. Inner‐ear impedances were in the low megohm range; in this respect the results confirm those of an earlier study from this laboratory. However, while in cadaver specimens the results were reasonably uniform, in live animals impedance appeared to increase with exposure to high SPLs. This increase in impedance appears to exert a protective function for the inner ear. Experiments to explore this latter function in more detail are being planned.

Differences of Interaural Phase and Level in Detection and Lateralization: 250 Hz

Dennis McFadden, Lloyd A. Jeffress, and Harold L. Ermey

J. Acoust. Soc. Am. Volume 50, Issue 6B, pp. 1484-1493 (1971); (10 pages) | Cited 6 times

Online Publication Date: 11 Aug 2005

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A narrow band of noise (50 Hz wide centered at 250 Hz) was passed through a phase‐shifting network and was then used as both masker and signal. The phase shifter permitted control over the phase angle α at which the signal and the masker were added. The masker was continuously present and was in‐phase interaurally N0); the signal could be presented in‐phase interaurally (S0) or 180° out‐of‐phase (Sπ). Detection data were taken for N0‐S0, α = 0° (increments) and α = 180° (decrements), and both detection and lateralization data were taken for N0‐Sπ for several values of α. A single‐interval psychophysical method was used throughout. For all subjects for all values of α, the masking‐level differences (MLDs) were positive and substantial. In the N0‐Sπ conditions, two cues were available to the subject for all values of α except 0° and 90°—an interaural phase (time) difference and an interaural difference in level. Between α = 0° and α = 90 °, the two cues are consonant, but between α = 90° and α = 180°, the two cues are in opposition, i.e., one cue indicates that the sound source is to one side of the median plane while the other cue indicates that it is to the other side. Some subjects were more sensitive to one of these cues, and other subjects were more sensitive to the other cue; this fact was apparent in both their detection and their lateralization data. For each subject there was a value of α between about 120° and 170° at which detection performance was good while lateralization was nearly impossible.

A Correlation Model of Binaural Masking Level Differences

Eli Osman

J. Acoust. Soc. Am. Volume 50, Issue 6B, pp. 1494-1511 (1971); (18 pages) | Cited 13 times

Online Publication Date: 11 Aug 2005

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This paper presents a quantitative functional model, called the correlation model, to be used for interpreting empirical results on binaural masking level differences (BMLDs), which are obtained experiments on the detection of sinusoidal signals embedded in binaural noise. The receiver is presumed to behave as if it computes a statistical decision variable equivalent to a linear combination of three quantities, the energy levels at the channels deriving from the two ears and the interchannel cross correlation, where the coefficients are dependent on the interaural noise cross correlation and the interaural amplitude ratio for noise but are completely independent of signal parameters. Additive internal noise is assumed. Equations for BMLDs are derived with the restriction of equal noise levels at the two ears. Predictions derived from the model are compared with empirical results from several studies. These show BMLDs for antiphasic, homophasic, and monoaural input configurations at different frequencies of tonal signal, and BMLDs for varying interaural correlations of signal and of noise, where the noise correlation is statistical or deterministic. Similarities and differences between the correlation model and another model, the equalization cancellation model, are discussed in detail.

Forward and Backward Masking: Testing a Discrete Perceptual‐Moment Hypothesis in Audition

Charles E. Robinson and Irwin Pollack

J. Acoust. Soc. Am. Volume 50, Issue 6B, pp. 1512-1519 (1971); (8 pages)

Online Publication Date: 11 Aug 2005

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A form of the discrete‐moment hypothesis of Stroud, usually studied in relation to vision, is tested in audition by means of the masking of a click by a preceding or a following noise burst. Threshold masking and temporal psychometric functions suggest that, if a discrete‐moment mechanism were operating, the time between successive moment onsets would be as short as 3 msec. Through a second‐choice procedure, we attempted to distinguish between a continuous moment or signal detection class of hypotheses and the discrete‐moment hypothesis. The results for one subject disagree with the prediction of the discrete‐moment hypothesis.

Responses of Some Neurons of the Cochlear Nucleus to Tone‐Intensity Increments

Robert L. Smith and J. J. Zwislocki

J. Acoust. Soc. Am. Volume 50, Issue 6B, pp. 1520-1525 (1971); (6 pages) | Cited 2 times

Online Publication Date: 11 Aug 2005

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The study concerns units of the cochlear nucleus of anesthetized Mongolian gerbils. The incremental stimuli consisted of short tone bursts at the units' CF (characteristic frequency) superimposed on 250‐msec pedestals of the same sound frequency and phase. The response firing rates were determined from PST (poststimulus time) histograms. In response to the pedestals, the maximum firing rate occurred at the tone onset and decayed subsequently to a steady state. The response to intensity increments was studied as a function of time delay from the pedestal onset to the increment onset. The incremental firing rate either remained constant or increased with the time delay, which means that the ratio between the incremental and pedestal firing rates always increased. The effect may be related to the psychophysical finding that intensity increments are the most difficult to detect when they occur at the pedestal onset.

Lateralization of Filtered Clicks

W. A. Yost, F. L. Wightman, and David M. Green

J. Acoust. Soc. Am. Volume 50, Issue 6B, pp. 1526-1531 (1971); (6 pages) | Cited 10 times

Online Publication Date: 11 Aug 2005

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Lateralization of brief clicks was studied while the frequency content of the clicks was altered by filtering. The subject was asked to discriminate a centered image, a pair of identical clicks that arrived simultaneously at the two headphones, from a displaced image, a pair of identical clicks in which the click to the left ear was slightly delayed. The discrimination of the lateral position deteriorated as the clicks were high‐pass filtered beyond 1500 Hz and was largely unaffected by low‐pass filtering. Masking with high‐pass and low‐pass noise showed that low‐pass noise severely disrupted the lateralization of the high‐pass clicks, but the high‐pass noise produced no disruption of the lateralization of the low‐pass clicks. Our results suggest that the discrimination of lateral position depends largely on the low‐frequency content of the click and thus, presumably, on the apical end of cochlear partition.

Effects of Smoothing and Quantizing the Parameters of Formant‐Coded Voiced Speech

A. E. Rosenberg, R. W. Schafer, and L. R. Rabiner

J. Acoust. Soc. Am. Volume 50, Issue 6B, pp. 1532-1538 (1971); (7 pages)

Online Publication Date: 11 Aug 2005

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A subjective evaluation of the effects of smoothing and quantization of the parameters for formant‐coded voiced speech has been carried out. Thresholds were obtained for the degree of smoothing or quantization of specified parameters associated with a just noticeable degradation of all‐voiced sentence material. Average quantization threshold levels obtained were: pitch period, 3.9 bits; first formant, 2.7 bits; second formant, 3.1 bits. The average of low‐pass filter bandwidth thresholds for the simultaneous smoothing of formants was 7.6 Hz per formant; for pitch‐period data the low‐pass filter bandwidth threshold was 3.9 Hz. With simultaneous low‐pass filtering and quantization, the estimated over‐all bit rate for the coded parameters of all‐voiced speech was approximately 200 bits/sec.

Degradation of DNA in High‐Intensity Focused Ultrasonic Fields at 1 MHz

W. T. Coakley and F. Dunn

J. Acoust. Soc. Am. Volume 50, Issue 6B, pp. 1539-1545 (1971); (7 pages) | Cited 1 time

Online Publication Date: 11 Aug 2005

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Gassy and degassed aqueous solutions of DNA were treated ultrasonically while monitoring the field for discrete cavitation events. At irradiation intensities greater than about 500 W/cm2, transient cavitation is shown to be responsible for the observed reduction in molecular weight. At intensities of 200 to 288 W/cm2, degradation of DNA was observed which did not depend upon transient cavitation.

Quantitative Relationships between Ultrasonic Cavitation and Effects upon Amoebae at 1 MHz

W. T. Coakley, D. Hampton, and F. Dunn

J. Acoust. Soc. Am. Volume 50, Issue 6B, pp. 1546-1553 (1971); (8 pages)

Online Publication Date: 11 Aug 2005

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An amoeba, Hartmannella castellanii, which possesses many features typical of higher‐order animal cells, was irradiated with 1‐MHz ultrasound while suspended in ordinary growth medium and in one with increased viscosity. The ultrasonically produced cavitation was monitored and a strong correlation is found between the number of discrete cavitation events occurring and the decrease in cell numbers, on irradiating at 515 W/cm2 for 10 min. The growth of treated cells was also examined.
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Comments on “Correspondence between Cochlear Microphonic Sensitivity and Behavioral Threshold in the Cat” [G. R. Price, J. Acoust. Soc. Amer. 49, 1899–1901 (1971)]

Peter Dallos

J. Acoust. Soc. Am. Volume 50, Issue 6B, pp. 1554-1554 (1971); (1 page)

Online Publication Date: 11 Aug 2005

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It is argued that the apparent covariance of cochlear microphonic (CM) and behavioral sensitivity is a result of the common dependence of both upon the middle‐ear transmission characteristics and not an indication of the causal role of CM in hearing.

Comment on “Proposed Explanation of Synchrony of Auditory‐Nerve Impulses to Combination Tones” [E. de Boer, P. Kuyper, and G. Smoorenburg, J. Acoust. Soc. Amer. 46, 1579–1581(L) (1969)]

J. L. Hall

J. Acoust. Soc. Am. Volume 50, Issue 6B, pp. 1555-1556 (1971); (2 pages)

Online Publication Date: 11 Aug 2005

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Interval histograms are computed from a threshold‐crossing model for auditory‐nerve activity. The calculations do not resemble real nerve histograms measured for combination‐tone frequencies. It appears unlikely that a threshold‐crossing model can explain the synchrony of auditory‐nerve impulses to combination tones.

Temporary Threshold Shifts Produced by Pure Tones and by Noise in the Absence of an Acoustic Reflex

John H. Mills and David J. Lilly

J. Acoust. Soc. Am. Volume 50, Issue 6B, pp. 1556-1558 (1971); (3 pages)

Online Publication Date: 11 Aug 2005

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Six subjects with an acoustic reflex and six subjects without an acoustic reflex were exposed on separate occasions to a 710‐Hz pure tone and to a ⅛‐oct band noise with an upper cutoff frequency of 710 Hz. Both exposures were 10 min at 110 dB sound‐pressure level. Temporary threshold shift (TTS) was measured at 1000 Hz. For the subjects with an acoustic reflex, the pure‐tone exposure produced 10 dB more TTS2 than the noise exposure. However, for the subjects without an acoustic reflex, the pure‐tone exposure and the noise exposure produced the same amounts of TTS. These results support the hypothesis that low‐frequency pure tones produce more TTS than low‐frequency bands of noise because of the differential effects of the acoustic reflex in responding to these two types of sounds.

Inhibition in the Auditory Nerve?

G. Moushegian, A. L. Rupert, R. D. Stillman, and I. P. Weiss

J. Acoust. Soc. Am. Volume 50, Issue 6B, pp. 1558-1560 (1971); (3 pages)

Online Publication Date: 11 Aug 2005

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Some recent findings from auditory nerve studies are considered as evidence for primary afferent inhibition.

Location of Slope Discontinuities in Glottal Pulse Shapes during Vocal Fry

S. L. Hamlet

J. Acoust. Soc. Am. Volume 50, Issue 6B, pp. 1561-1562 (1971); (2 pages)

Online Publication Date: 11 Aug 2005

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Comparison of the speech waveform with ultrasonic signals from the larynx recorded simultaneously gives information about the temporal properties of the glottal source. Physiological information obtained with this technique corroborates the time relationships between speech output and excitation waveform found with inverse filtering.
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