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Dec 1977

Volume 62, Issue S1, pp. S1-S102

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back to top Session MM. Psychological Acoustics VI: General Psychological Acoustics
Contributed Papers
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On the nondetectability of phase delay distortion in hearing aids (A)

B. Voroba and A. A. Beex

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S92-S92 (1977); (1 page)

Online Publication Date: 11 Aug 2005

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Since the time of Ohm and Helmholtz, researchers have argued over the detectability and importance of phase shift effects. Rarely has this subject been explored with hearing impaired listeners or their prosthetics. An experiment was performed in which normal‐hearing and hearing‐impaired subjects were presented with the combination of high‐ and low‐pass speech components. The high‐pass frequencies were alternately time delayed, or nondelayed, with respect to the low‐pass signals so as to simulate the phase characteristics of a hearing aid. All subjects uniformly reported no detectable difference between the various test conditions suggesting that present hearing‐aid phase characteristics have little or no detrimental effect upon listener perceptions.
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Measurement of head movement during auditory localization (A)

S. Gilman, D. Dirks, and S. Hunt

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S92-S92 (1977); (1 page)

Online Publication Date: 11 Aug 2005

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A system has been designed to track human‐head movement response to sound originating at different azimuth locations with respect to the head. A videotape record is made of a “point‐source” light carried on a small, lightweight “beanie” mounted on the listener's head. Movement of the head generates an equivalent movement of the light which is being monitored by the video camera and recorded on tape. Also, speaker location, time, and actual sound signal are recorded. Circuitry has been designed which determines the x‐y coordinates of the spot image with respect to the video synch pulses. These are available from a modified video monitor either in real time or from tape replay. This same circuitry interfaces to a computer programmed to take the coordinate and timing information, apply a calibration and process the data into time‐varying head position and velocity. Both digital and graphic outputs are available and examples of graphic printout of typical head movement response are given. System hardware and programs are capable of expansion into 3‐axis operation.
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Azimuth effects on the Kemar Mannequin (A)

Samuel Gilman, Donald Dirks, and Warren Kumley

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S92-S92 (1977); (1 page)

Online Publication Date: 11 Aug 2005

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The effect of head shadow and diffraction by the Kemar mannequin was explored with both pure‐tone and pink‐noise sound fields in an anechoic chamber. Polar recordings of 360° rotation of the mannequin were made for each ⅓ octave from 0.25 to 12.5 kHz with the point source on the same horizontal plane as the Zwislocki coupler in the mannequin′s ear. Simultaneous magnetic tape recordings were transferred digitally to a computer programmed to compare the data with published human data. Comparisons were made for the full azimuth range for each frequency and for the full frequency range at each 15° of azimuth. Results shown that pink‐noise data agrees closely with averaged human results [E.A.G. Shaw, J. Acoust. Soc. Am. 56, 1848–1861 (1974)]. Pure tone results show good correspondence with the same averaged human data at low and middle frequencies but show deviant peaks at higher frequencies. At least some of these variations appear to be related to detailed pinna geometry.
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Localization through hearing aids (A)

Anna K. Nabelek, Tomasz Letowski, and Reed Norwood

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S92-S92 (1977); (1 page)

Online Publication Date: 11 Aug 2005

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Stereophonic signal presentation was used to assess localization abilities through ear‐level hearing aids. The experiment was performed in a small sound insulated room. Two loudspeakers were 2 m away from the subject forming ±30° azimuths. The subject was sitting on a chair with a head rest. He faced two strings 30 cm apart hanging on the midline between the loudspeakers and lined them up visually. Two additional strings are marked ±15° azimuths. The subject varied the position of a phantom source by controlling the relative level of signal (uninterrupted flow of speech) by means of a potentiometer. Four conditions were tested: unaided, aided with identical gains of the hearing aids and aided with the gains 10 dB different (right or left ear more amplified). Each subject made 10 adjustments for −15, 0, and +15° azimuth. Each subject was tested two times. Seven subjects with normal hearing produced unaided data similar to reported previously [(Theile and Plenge, J. Aud. Eng. Soc. 25, 196–200 (1977)]. The results for identical gains were similar to unaided results. The asymmetrical conditions produced images shifted toward the ear getting more amplification. The average shift was +4.6 and −2.6 dB for left and right ear more amplified, respectively. However the amount of shift varied among subjects. The method might have potential for testing localization abilities of hearing‐impaired subjects. [Supported by NIH NISND grant.]
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The locatability of vocalizations in Old World monkeys (A)

C. H. Brown, M. D. Beecher, D. B. Moody, and W. C. Stebbins

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S92-S93 (1977); (2 pages)

Online Publication Date: 11 Aug 2005

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The acuity of directional hearing in Old World monkeys (Macaca) was assessed psychophysically through positive reinforcement operant conditioning procedures. The monkey's observing response, contact with the response disk, initiated a train of acoustic stimuli presented from the standard location, 0° azimuth. Intermittently the location of the stimulus changed from the standard to one of several comparison locations. Monkeys reported the detection of a change in the azimuth of the signal by releasing contact with the response disk. Thresholds for the acuity of acoustic localization were determined under free‐field conditions in an anechoic chamber by the method of constant stimuli. Monkeys were tested with an array of natural calls and bandpass‐filtered components of calm sampling several categories of conspecific vocalizations. The results indicate that frequency modulation and bandwidth were relatively more salient than the harmonic content of the call for directional hearing. The locatability of vocalizations may be selected by the biosocial context in which they are emitted. [Work supported by NSF.]
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Relationship of tonal masking to speech intelligibility in noise for listeners with sensorineural hearing damage (A)

B. Leshowitz

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S93-S93 (1977); (1 page)

Online Publication Date: 11 Aug 2005

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The present investigation sought to establish empirical evidence for the audiological observation that listeners with normal pure‐tone thresholds below 2000 Hz and selective high‐frequency sensorineural hearing loss often experience great difficulty perceiving speech in a noise background. For patients with either noise trauma or presbyacusis, masked‐speech intelligibility thresholds (S/N) were about 10 dB higher than for normal observers. In an effort to provide a psycho‐acoustical explanation for the speech communication deficit, pure‐tone masking patterns were measured. Relative to the normal control group, listeners with high‐frequency hearing loss showed as much as 30 dB more upward spread of masking, often in frequency regions of normal pure‐tone threshold. The strong positive relationship between the masked‐speech intelligibility threshold and the upward spread of masking suggests that it may be possible to predict the patient's speech perception handicap in noise from audiometric measurements of masked threshold. Implications of the present work for development of close‐talking‐microphone hearing aids will be discussed. [Work supported by an NIH Postdoctoral Fellowship awarded to the author at the Institute for Perception Research, Eindhoven, The Netherlands.]
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Study of different criteria for identifying significant amounts of threshold shift among personnel who work in potentially hazardous noise (A)

D. C. Gasaway, H. C. Sutherland, Jr., and Richard L. Medina, Jr.

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S93-S93 (1977); (1 page)

Online Publication Date: 11 Aug 2005

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Monitoring the hearing of persons who routinely work in potentially hazardous noise areas serves to identify changes, or shifts, in hearing that may be attributed to excessive exposures. Since October 1956 (21 years) medical personnel of the US Air Force have used threshold shifts (current annual audiogram compared against individual reference) to identify persons who may be acquiring a sensorineural loss of hearing due to noise. Fortunately, this procedure has proven of extreme value since it identifies the occurrence of a noise‐induced hearing loss during the earliest stages and thus, when combined with proper medical management, prevents the occurrence of significant amounts of hearing loss in the speech hearing range. The authors describe the results of a study of the relative effectiveness of 22 different criteria (or methods) that could be used to identify shifts in hearing (significant threshold shifts, STS) that may be attributed to excessive noise. A total of 56,678 military and civilian employees was selected for this study. The proportions of the total sample that would be identified using the different STS criteria are given; proportions ranged from 7.18% to 65.19%. Median hearing level for the total sample, as well as hearing levels for each of the groups identified by the 22 STS criteria are also reported.
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Asymptotic temporary threshold shift (A)

John P. Barry and Robert C. Bilger

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S93-S93 (1977); (1 page)

Online Publication Date: 11 Aug 2005

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Five men having normal pre‐exposure audiograms were monaurally exposed in a diffuse sound field for 24 hours to octave‐band noise centered at 500 or 2000 Hz at 90 or 80 dB SPL, respectively. Each subject's exposures were two weeks apart. The growth of threshold shift was measured 10 times, and recovery was followed for a course of three days post exposure by a fixed‐frequency‐Bekesy‐tracking procedure. Functional asymptotic threshold shift (ATS) was achieved for either noise exposure within eight hours at all 11 audiometric test frequencies. The maximum ATS for either exposure was the upper cut‐off frequency of the noise with significant spread to the first octave above the noise's center frequency. For each exposure, growth was linear in logarithmic space. For multiple exposures on one subject at each band, the relationship between asymptotic level and noise intensity appeared to be linear with a slope of 1.6. Group data demonstrated that recovery from a 16.7 dB asymptotic threshold shift at 707 Hz required 98 h and was biphasic. Recovery from an 11.3 dB ATS at 2828 Hz required 20 h. Recovery from either noise was linear in logarithmic space.
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An absolute coupling between psychological magnitudes of numbers and loudness (A)

J. J. Zwislocki, S. J. Bolanowski, A. J. Capraro, and D. A. Goodman

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S93-S93 (1977); (1 page)

Online Publication Date: 11 Aug 2005

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It is usually assumed that, in magnitude estimation and production procedures, subjects assign numbers to sensation magnitudes on ratio scales, i.e., according to ad hoc units. However, S. S. Stevens and others have found that units imposed by the experimenter produce response biases, and Hellman and Zwislocki were able to explain a strong response bias in some of their data by assuming that their subjects tended to pair numbers and loudness magnitudes on an absolute scale. This implies that, through common usage, numbers become associated with psychological magnitudes on a one‐to‐one basis, and a natural unit develops. Some subsequent experiments confirmed this hypothesis. Present experimental results of loudness scaling performed by several groups of subjects with varying degrees of sophistication reveal an unexpectedly small variability of the median scale units used by the groups and asymmetrical learning effects.
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Signal detection in children: ROC determination from reaction time distributions (A)

A. Yonovitz, J. T. Lozar, Dianne R. Ferrell, and Bernard Harris

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S93-S94 (1977); (2 pages)

Online Publication Date: 11 Aug 2005

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The use of signal detection with children provides a precise method for investigating auditory system parameters. This study investigated the use of signal detection with normal hearing children ages 6–12. A yes‐no procedure was designed such that a child could easily learn the task. A trail was initiated by the child pressing a single manipulandum. After initiation of the trial a 1‐sec delay occurred. A “listen” light then occurred simultaneously with a randomly presented (0.50 probability) 1000‐Hz pure tone. Tonal duration was three seconds. The child's task was to release the manipulandum if the tone was perceived. If the tone was not perceived the child was instructed to continue pressing the manipulandum. Tangible reinforcement was automatically dispensed for hits. Using this procedure a dense distribution of latencies were recorded for hits and false alarms. By redefining “yes” responses at 50‐msec intervals different hit and false‐alarm probabilities were obtained. These probabilities were used to construct ROC curves. This method generated a large number of points on the ROC curve with great economy of experimental time. Several stimulus intensities were used to generate functions relating intensity with d′.
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Perception of clicks in music (A)

Andrew H. Gregory

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S94-S94 (1977); (1 page)

Online Publication Date: 11 Aug 2005

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Subjects were asked to judge the position of a click which occurred during a short piece of music. Clicks were on average judged to be later than their actual position for a slow tune, but almost no bias in the judgement of click position was found for a fast tune. The click and the music were presented through headphones to different ears, and the clicks were judged to be significantly later if they arrived at the right ear rather than the left. There was also a significant tendency for clicks to be attracted to phrase boundaries in the music. These last two results are similar to those from experiments with a click during speech, but the late judgements of a click in music contrasts with the tendency for early judgements of a click in speech.
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