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Nov 1975

Volume 58, Issue S1, pp. S2-S132

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back to top Session BB. Psychological Acoustics III: Binaural Interaction
Contributed Papers
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Coherence function for speech (A)

Lamar L. Young, Jr., Cheryl Parker, and Raymond Carhart

J. Acoust. Soc. Am. Volume 58, Issue S1, pp. S54-S54 (1975); (1 page)

Online Publication Date: 11 Aug 2005

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It is well known that the lateralization of an auditory image depends upon the difference in the time of arrival of the signals at the two ears. Based upon modifications of the procedure used by Cherry and Sayers [J. Acoust. Soc. Am. 28, 889–895 (1956)], a two‐alternative forced‐choice experiment was employed to investigate the DL for lateralization of an ongoing speech stimulus. In one of the stimulus intervals the binaural speech signal was presented diotically, and in the other interval interaural time disparities of 0.0, 0.015, 0.030, 0.060, 0.075, 0.090, 0.250, and 1.0 msec were created between the binaural signals. The listener's task was to indicate the interval in which the Δt was present. The results show that listeners were able to detect small interaural time differences with 75% performance being reached at a Δt of 0.021 msec. The data has been plotted in terms of a coherence function for speech which is discussed. [Supported by a grant from NINCDS.]
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Some auditory illusions reheard: dichotic listening to discrete frequencies (A)

A. S. House and R. E. Wohlford

J. Acoust. Soc. Am. Volume 58, Issue S1, pp. S54-S54 (1975); (1 page)

Online Publication Date: 11 Aug 2005

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Listeners heard competing (dichotic) discrete‐frequency stimuli [D. Deutsch, Nature, 251, 307–309 (1974); J. Acoust. Soc. Am. 56, Suppl., S25 (1974); Op. Cit. 57, 1156–1160 (1974)]. Frequencies, energy levels, phase conditions, harmonic relations, temporal alignments, etc., were manipulated in a number of different listening and response configurations. Findings indicate that one pattern of response predominates: In general, when the signals to the two ears are of equal amplitude, the percept (1) sounds like one of the two signals presented (i.e., is unfused), (2) is lateralized to the side receiving the signal that has a loudness advantage, and (3) has a pitch more appropriate to the signal presented to one ear (independent of ear report), with the left‐ear signals showing a preference. This response pattern is sensitive to listener hearing characteristics and, in part at least, to listener handedness. The response phenomena are relatively insensitive to signal manipulations, except that that change loudness characteristic and/or involve channel delays.
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Signal detectability as a function of interaural signal‐frequency disparity and signal duration (A)

D. Wesley Grantham, John A. Karpicke, and Donald E. Robinson

J. Acoust. Soc. Am. Volume 58, Issue S1, pp. S54-S54 (1975); (1 page)

Online Publication Date: 11 Aug 2005

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The relationship between interaural signal‐frequency disparity (Δf) and signal duration (t) was investigated using a two‐alternative temporal forced‐choice procedure. The signals consisted of a tone (400 Hz) in one ear and a tone of a different frequency (400 + Δf Hz) in the other ear, where Δf = 4, 8, or 16 Hz. As a reference condition a diotic signal (Δf = 0 Hz) was also employed. Signal duration was either 256, 512, 1024, or 2048 msec. All signals were presented in a background of wide‐band, diotic Gaussian noise. In the diotic condition performance improved as t increased. In the dichotic conditions, for a constant signal duration, performance deteriorated (average of 1 dB) as Δf increased; for a constant Δf, performance improved (average of 2.5 dB) as t increased. The results are discussed in terms of the number of alternating diotic (SO) and phase‐reversed (Sπ) “looks” available in a signal interval.
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Frequency bands for binaural interactions (A)

J. Neutzel and E. Hafter

J. Acoust. Soc. Am. Volume 58, Issue S1, pp. S54-S54 (1975); (1 page)

Online Publication Date: 11 Aug 2005

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Earlier reports [Henning, J. Acoust. Soc. Am. 55, 84–90 (1974); Neutzel and Hafter, J. Acoust. Soc. Am. 56, S56(A) (1975)] have shown that temporal information derived from the envelopes of amplitude‐modulated signals can be used for lateralization even when the carrier frequencies are interaurally discrepant. This study was intended to examine that fact more closely. Lateralization was measured using digitally generated bursts of amplitude‐modulated tones of duration 200 msec and amplitude 40 dB SPL. A 50–1600 Hz bandpass noise with an overall level of 60 dB SPL masked low‐frequency distortions, while the signals themselves were filtered at 200 Hz below and above the lower and upper sidebands. The digital methods employed allowed arbitrary choices of frequency and phase relations; consequently, inharmonic frequency relations between the modulation and carrier frequencies could be used. These were valuable, both as a precaution against monaural cues and as a means of assessing the degree of interaural spectral overlap necessary for lateralization. We find that the binaural overlap bands obtained with anharmonic stimuli are narrower than those reported for carriers which are multiples of the modulator. However, lateralization with interaurally indentical carriers is excellent, regardless of whether the carrier to modulation relation is harmonic.
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Lateralization of partials of complex tones with pure tones (A)

Werner A. Deutsch

J. Acoust. Soc. Am. Volume 58, Issue S1, pp. S54-S54 (1975); (1 page)

Online Publication Date: 11 Aug 2005

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The ability to detect lateralization images of individual partials of harmonic tone complexes with pure tones was measured in a yes/no task. It is supposed that partials of complex tones build up lateralization images with pure tones of equal frequency and amplitude. It has been found that the upper limit of lateralization produced by introducing interaural time differences is slightly reduced from that in pure‐tone‐pure‐tone cases. No difference in correlation has been found between lateralization obtained with partials resolved or unresolved by the ear or with those partials covering the “dominance region.” The results are in good agreement with data reporting of fusion at higher frequencies between dichotically presented signals with gross interaural frequency differences. [This work was supported by the AKG, Vienna, Austria.]
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Critical bandwidth in lateralization: Effect of level (A)

Bertram Scharf, Carol H. Meiselman, and Mary Florentine

J. Acoust. Soc. Am. Volume 58, Issue S1, pp. S55-S55 (1975); (1 page)

Online Publication Date: 11 Aug 2005

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The onset‐time difference ΔT needed to lateralize 30‐msec dichotic tone bursts toward the leading ear was measured as a function of the frequency difference ΔF between the burst in one ear and the burst in the other ear. An adaptive procedure (a variation of BUDTIF) was used to concentrate judgments in the vicinity of 75% correct. Signal frequencies were centered at a geometric mean of 2000 or 6000 Hz. The level in the right ear was set near 25, 50, or 80 dB SPL. At each of the three reference SPLs, all tone bursts in the right ear were presented at the same loudness level. The level in the left ear was adjusted to center the image. Threshold ΔT remained approximately constant as ΔF increased up to the critical band, which is 300 Hz at a center frequency of 2000 and 1100 Hz at 6000 Hz. Beyond the critical band, threshold ΔT increased with ΔF. The critical bandwidth did not change with level for either listener, but the rise in threshold beyond the critical band became steeper at lower levels. These results provide further evidence that the dichotically measured critical band has the same width as the monaurally measured critical band, and that critical bandwidth is independent of sound pressure level. [Research supported by NIH Grant No. NS 07270.]
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Measurements of the precedence effect (A)

P. M. Zurek and B. Leshowitz

J. Acoust. Soc. Am. Volume 58, Issue S1, pp. S55-S55 (1975); (1 page)

Online Publication Date: 11 Aug 2005

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Interaural time and amplitude discrimination tasks were employed to assess the relative influence of direct and echoed sound in determining localization. Using headphones, a brief noise burst was presented binaurally, followed after a time, ISI, by a second binaural noise burst, an echo of the primary sound. Subjects were asked to detect interaural time or intensity differences on either the primary or the echo bursts in a forced‐choice task. In general, time, and amplitude jnds are consistent with previous descriptions of the precedence effect. With primary and echo noise bursts at equal levels, interaural time and amplitude jnds for the second burst are considerably greater than those for the primary burst and reach a maximum with an ISI of about 1 msec. Attempts are made to relate the precedence effect to temporal masking phenomena and results from other discrimination tasks employing similar temporal paradigms.
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Binaural intensity JNDs for transients (A)

E. Hafter, H. Aronow, R. Dye, and J. Nuetzel

J. Acoust. Soc. Am. Volume 58, Issue S1, pp. S55-S55 (1975); (1 page)

Online Publication Date: 11 Aug 2005

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Difference thresholds for interaural intensity (ΔI) were measured as a function of overall interaural intensity disparity (I) using a same‐different lateralization paradigm. The signals tested were high (3–4 kHz) or low (0.1–2 kHz) frequency bandpass clicks. Values of I ranged from 0 to 32 dB, while the average overall level for each binaural click was maintained at 48 dB SPL by symmetrically dividing the values of I and ΔI between the two ears. Controls were included to account for information contained in monaural loudness increments, and differences between binaural and monaural thresholds were taken as measures of subjects' intensity‐based lateralization abilities. Hafter and DeMaio [J. Acoust. Soc. Am. 57, 181–186 (1975)], also using clicks, reported that sensitivity to interaural time (Δt) falls off gradually as the overall difference (t) increases. Within the framework of a model which equates intensity differences to time differences, use of these earlier data may permit extraction of “true” intensity‐based lateralization, independent of both monaural and temporal cues. Our results verify that, at least for the high‐frequency range, such interaural intensity differences are indeed useable cues for lateralization. Acuity for the interaural intensity cue declines slowly for images lateralized away from the midline; use of the cue deteriorates completely as I reaches values near 24 dB. [Supported in part by grants from the NIH and HIMH.]
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Intensity and frequency discrimination in one and two ears (A)

Walt Jesteadt and Craig C. Wier

J. Acoust. Soc. Am. Volume 58, Issue S1, pp. S55-S55 (1975); (1 page)

Online Publication Date: 11 Aug 2005

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Early studies of intensity and frequency discrimination reported that discrimination was generally better with two ears than with one. Unlike binaural summation or MLDs, this binaural phenomenon has received little attention and has not been systematically explored. In the present experiment, intensity and frequency discrimination for pure tones were measured at 250, 1000, and 4000 Hz using a 2IFC‐adaptive procedure. Signals were presented at 70 dB SPL in a low‐level broad‐band noise. Intensity and frequency discrimination were measured for each ear individually (SmNm) and for both ears, with signal and noise in phase (S0N0). In all conditions, discrimination with two ears was better than discrimination with either ear individually. The improvement in performance was approximately equal to the √2 increase in d′ that an information model would predict for a system with input from two independent channels.
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Magnitude of JNDs for diotic and dichotic perception of spectrally colored noise (A)

A. H. Koenig, D. A. Berkley, T. H. Curtis, and J. B. Allen

J. Acoust. Soc. Am. Volume 58, Issue S1, pp. S55-S55 (1975); (1 page)

Online Publication Date: 11 Aug 2005

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As part of a series of studies concerned with the binaural perception of reverberant sound, just noticeable differences (JNDs) were determined for spectrally colored noise presented both diotically and dichotically. Test stimuli were prepared by passing white noise samples through simple all‐zero filters consisting of a delay, an attenuator, and an adder. By adjusting the delay and attenuation, various amounts of spectral distortion could be obtained. The sensitivity of the listener to changes in the amount of distortion or coloration was measured under two listening modes. For the diotic case, the same spectrally distorted noise was presented to both ears; for the dichotic case, pairs of complimentary filters were made simply by changing the sign of the attenuator in one of the filters. The listeners were less sensitive to the presence of coloration for the dichotic both in terms of absolute threshold and for the number of JNDs. The results will be discussed in terms of existing binaural processing models.
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Determination of masking‐level differences in a reverberant environment (A)

A. H. Koenig, J. B. Allen, D. A. Berkley, and T. H. Curtis

J. Acoust. Soc. Am. Volume 58, Issue S1, pp. S55-S55 (1975); (1 page)

Online Publication Date: 11 Aug 2005

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A masking‐level difference paradigm was used to measure release from masking in a reverberant environment. Microphones were placed in the ears of a mannequin which was situated in a reverberant chamber. A single white‐noise source was fed into loudspeaker also situated in the chamber with the loudspeaker facing one corner of the chamber to minimize the direct sound reaching the mannequin. The output of each microphone served as the masker, while the signal (250‐Hz pulsed tone or speech) was electrically inserted at the subject's earphones. For the diotic case, the output of one of the microphones was fed to both ears of the subject. For both signals, the MLD was found to be approximately 3 dB. Results will be discussed in terms of a decorrelating effect produced by longterm reverberation.
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