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Dec 1972

Volume 52, Issue 6B, pp. 1599-1734


Comparable Coupler and Real‐Ear Measurements on Supraaural‐ and Insert‐Type Earphones

H. W. Bryant

J. Acoust. Soc. Am. Volume 52, Issue 6B, pp. 1599-1606 (1972); (8 pages)

Online Publication Date: 12 Aug 2005

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Tests on supraaural‐ and insert‐type earphones for telephone applications, designed from measurements with real ears and the American National Standards Institute (ANSI) 2‐ and 6‐cm3 calibration couplers, are reported. Disagreements between real‐ear and coupler data are rationalized by reducing the basic 2‐cm3 volume to 1.3 cm3 and employing an approximate transfer characteristic to relate the supraaural coupler data to a common plane of reference corresponding to the tympanum position. Several experimental couplers for obtaining data within the telephone speech band, which permit measurements on the two types of earphone at the common plane, are described.

Postmasking Recovery of Human Click Action Potentials and Click Loudness

Alfred C. Coats and J. Ray Dickey

J. Acoust. Soc. Am. Volume 52, Issue 6B, pp. 1607-1612 (1972); (6 pages)

Online Publication Date: 12 Aug 2005

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We compared postmasking recovery of click action potentials (APs) with that of click loudness in seven otologically normal subjects. The APs were recorded by averaging the pickup of a nonsurgically placed, external‐meatus electrode. We found that increasing masking duration slowed recovery of both click loudness and click AP amplitude. However, the rate of recovery of click loudness was much faster than the rate of recovery of click AP amplitude. There were order of magnitude differences between the effects of click attenuation and of masking on click microphonic and AP latency. It is therefore very unlikely that middle‐ear muscle contractions influenced the results. The relatively slow postmasking AP recovery (complete recovery requiring up to 500 msec) and the masking‐duration effect probably originate in the sensory end‐organ. These effects can therefore be regarded as manifestations of “sensory adaptation.” However, the comparatively rapid postmasking recovery of click loudness suggests that some form of (central?) compensation prevents subjective appreciation of auditory adaptation.

Cooperation of Listener and Computer in a Recognition Task. II. Effects of Computer Reliability and “Dependent” versus “Independent” Conditions

D. W. J. Corcoran, J. L. Dennett, and A. Carpenter

J. Acoust. Soc. Am. Volume 52, Issue 6B, pp. 1613-1619 (1972); (7 pages)

Online Publication Date: 12 Aug 2005

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Two experiments are reported upon the influence of a computer aid on the recognition of complex sounds. Twelve 1½‐h training and test sessions were conducted over a period of two weeks. Measures of unaided listener performance (L), computer performance (C), and combined performance (C & L) were obtained. In Expt. 1 the reliability of the computer was varied, while audio signal‐to‐noise (S/N) ratio was kept constant. The results showed (1) that as C increases so (C & L) increase; (2) that excessively high C performance reduces the listeners performance; and (3) that the strategy involved in using the computer and audio displays tends to evolve with training. Initially, attempts to compromise between computer and audio information often lead to (C & L) performance lower than it need be if the poorer display had been ignored. Later, the more valid display tends to be relied upon and finally in certain instances an optimal strategy tends to emerge in which (C & L) performance is above both C and L. Experiment 2 compared “dependent” and “independent” systems. In the former condition audio and computer displays are fed to the same observer; in the independent condition one observer receives the audio imputs and a partner views the computer display and makes the final (C & L) decision. No major differences in overall preferences were observed, except that the independent condition yields poor L performance.

Network Representation of the External Ear

Mark B. Gardner and Melville S. Hawley

J. Acoust. Soc. Am. Volume 52, Issue 6B, pp. 1620-1628 (1972); (9 pages) | Cited 2 times

Online Publication Date: 12 Aug 2005

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Two of the basic requirements of an ear‐model design is that the transfer characteristic of the ear canal and the impedance as measured at the eardrum closely agree with results obtained on real ears. In the case of the electrical analog model, this requires that the number of sections that are used to represent the ear canal provide an upper cutoff well beyond the highest frequency under study. This is particularly true where the effect of ear‐canal taper is of interest. For these purposes, 10‐section analog networks of uniform and of tapered design were employed. For network representation of the eardrum and the adjacent connecting structures, the effectiveness of one‐, two‐, three‐, and four‐branch terminations were explored. Of these, the two‐ and the four‐branch analog networks were found to provide the best overall representations.

New Boundary Conditions and Results for the Peterson‐Bogert Model of the Cochlea

C. Daniel Geisler and Allyn E. Hubbard

J. Acoust. Soc. Am. Volume 52, Issue 6B, pp. 1629-1634 (1972); (6 pages)

Online Publication Date: 12 Aug 2005

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The Peterson‐Bogert model of the cochlea [J. Acoust. Soc. Amer. 22, 369–381 (1950)] specifies, as one of its boundary conditions, zero pressure at the round window. This specification is equivalent to eliminating the round‐window membrane. We have substituted a new boundary condition, representing the round‐window membrane with an acoustic stiffness. With the new boundary condition, the equation for p+(x) requires a new solution, and a new value of p− (x) at x = 0 is needed. The solution for p+ (x) and the necessary value of p− (0) are given as a function of frequency for sinusoidal stimulation. The latter value is used as the input to the Peterson‐Bogert type of model of the basilar membrane. The model's input impedance as well as the relative displacement between the oval and round windows are also given. These relationships are compared with experimental findings.

Discrimination of Interaural Time and Intensity

John D. Gilliom and Robert D. Sorkin

J. Acoust. Soc. Am. Volume 52, Issue 6B, pp. 1635-1644 (1972); (10 pages) | Cited 1 time

Online Publication Date: 12 Aug 2005

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Discrimination tasks with a 500‐Hz tone and involving various combinations of binaural time and intensity cues were used to generate binaural discrimination spaces. The resultant spaces indicate that the sensations which arise from interaural time cues and interaural amplitude cues are correlated with a correlation coefficient of approximately 0.88; that is, a large fraction of the total sensation arising from one interaural cue will add or subtract as a scalar quantity with the sensation produced by the other interaural cue, but a residual sensation will always remain for all combinations of time and intensity cues. The same spatial framework provides a good description of the results of time intensity trading tasks. When applied to an MLD detection paradigm, this framework provides predictions which are in qualitative agreement with masking studies using tones and narrow‐band noise as maskers.

A Response‐Contingent Measure of Proportion Correct

Kent Gummerman

J. Acoust. Soc. Am. Volume 52, Issue 6B, pp. 1645-1647 (1972); (3 pages)

Online Publication Date: 12 Aug 2005

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Current methods of calculating proportion correct from the raw data of forced‐choice experiments involve obtaining the proportion of times that a given response was made, contingent upon the occurrence of the corresponding stimulus. Here, another method is introduced: obtaining the proportion of times that a given stimulus occurred, conditional upon the occurrence of the corresponding response. Both of these computational methods are examined with respect to their stability over variations of sensitivity, response bias, and stimulus bias.

Modeling and Simulation of the Cochlear Potentials of the Guinea Pig

C. A. Laszlo, J. H. Milsum, and R. P. Gannon

J. Acoust. Soc. Am. Volume 52, Issue 6B, pp. 1648-1660 (1972); (13 pages)

Online Publication Date: 12 Aug 2005

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A combination of mathematical modeling techniques and computer simulation methods has been used for the interpretation of the behavior of the experimentally observed cochlear potentials. In particular, the models of the mechano‐acoustical system and of the electrical potential generating mechanism of the transducer cells have been derived in terms of state variables and of equivalent functional relationships, respectively. These formulations allow economical numerical solution of the complex equations which describe cochlear functions. Using these techniques we have been able to confirm that nonlinearity of the individual haircell output is compatible with the observed apparent linearity of the experimentally observed macroscopic CM (cochlear microphonic) potential and that effective low‐pass filtering reduces distortion in the measured potential waveform due to the interaction of the electrical outputs of the haircells along the basilar membrane. This filtering is not influenced to a great extent by the attenuation along the cochlea. Further filtering may also be contributed by the RC networks formed by the various membrane capacitances and resistances. Comparison of the experimental and simulated CM vs SPL functions (frequency as parameter) shows that a simple phase cancellation process is not sufficient, but that an additional mechanism must be postulated to account for the decrease of the CM at very high sound intensities; the IHC (internal haircell) output is assumed to be 20 dB less sensitive than the OHC (outer haircell) output and of opposite sign. A similar comparison for the CM amplitude, CM phase, and SP− amplitude as functions of frequency (SPL as parameter) also provides good agreement. Our results demonstrate that the particular behavior of the basilar membrane and the interference effect between haircell outputs account for the majority of electrical phenomena observed by the classical differential electrode method.

The Critical Masking Interval

M. J. Penner, Charles E. Robinson, and David M. Green

J. Acoust. Soc. Am. Volume 52, Issue 6B, pp. 1661-1668 (1972); (8 pages) | Cited 4 times

Online Publication Date: 12 Aug 2005

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We investigated the concept of a critical masking interval, the time period during which noise is effective in masking a brief signal. The signal was a 100‐μsec click temporally placed in the center of a gated‐noise masker. Both the click and the noise were low‐pass filtered so that the power spectra of signal and noise have similar shape. The duration of the noise masker was varied from 100 μsec to 300 msec and two noise levels were employed. Like the estimate of the critical bandwidth, the estimate of the critical masking interval can be made in two independent ways. First, for long durations of the noise masker, the ratio of click energy to overall noise power indicates that the critical masking interval is about 14 msec. Second, progressively shortening the duration of the noise masker did not improve detectability until the duration was less than approximately 10 msec. The near agreement of these two independent estimates supports our interpretation of the data in terms of the concept of a critical masking interval.

Response Patterns of Single Cochlear Nerve Fibers to Click Stimuli: Descriptions for Cat

Russell R. Pfeiffer and Duck On Kim

J. Acoust. Soc. Am. Volume 52, Issue 6B, pp. 1669-1677 (1972); (9 pages) | Cited 6 times

Online Publication Date: 12 Aug 2005

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Response patterns to click stimulation of 907 single cochlear nerve fibers, having characteristic frequencies below 2000 Hz, can be separated into two populations on the basis of salient features. Population I consists of approximately 93% of the fibers, and Population II consists of approximately 7% of the fibers. A statistical description of the correlation between properties of response patterns of Population I fibers and stimulus level and characteristic frequency is given. For the Population I fibers, with characteristic frequencies below 500 Hz, deviations from the precise interlacing of preferred times of spike discharges in response to rarefaction and condensation clicks, as well as some instances of biased response to condensation clicks are described. The features that set Population II fibers apart from those of Population I are given, and a correlation of these populations with anatomical details of innervation is suggested.

Latency of Whole‐Nerve Action Potentials: Influence of Hair‐Cell Normalcy

Chang‐Yang Wang and Peter Dallos

J. Acoust. Soc. Am. Volume 52, Issue 6B, pp. 1678-1686 (1972); (9 pages) | Cited 2 times

Online Publication Date: 12 Aug 2005

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An experimental hypothesis was derived based on the findings of the clinical simultaneous binaural median plane lateralization test and the literature review of the latency of action potentials (AP). It states that the latency of action potentials as a function of absolute signal intensity (SPL) in cochleae with different degrees of hair‐cell losses is identical to that in normal cochleae at suprathreshold levels for signals with a given spectral content and a fixed rise time. The pathological cochleae were created by injections of kanamycin in guinea pigs and were monitored histopathologically, utilizing the surface preparation technique. The results show that the latency of AP as a function of SPL remains constant regardless of the pattern and degree of hair‐cell loss in the cochlea, and they consequently prove that the hypothesis of this experiment cannot be rejected. For a signal with a given frequency and a fixed rise time, the latency of the onset AP apparently depends only on the magnitude of the displacement of the basilar membrane regardless of the overall magnitudes of CM or AP.

Automatic Speaker Recognition Based on Pitch Contours

B. S. Atal

J. Acoust. Soc. Am. Volume 52, Issue 6B, pp. 1687-1697 (1972); (11 pages) | Cited 3 times

Online Publication Date: 12 Aug 2005

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An automatic speaker‐recognition method, using temporal variations of pitch in speech as a speaker‐identifying characteristic, is described. The pitch data was obtained from 60 utterances, consisting of six repetitions of the same sentence, spoken by 10 speakers. The pitch data for each utterance was represented by a 20‐dimensional vector in the Karhunen‐Loève coordinate system. The 20‐dimensional vectors representing the pitch contours were linearly transformed so that the ratio of interspeaker to intraspeaker variance in the transformed space was maximized. A reference vector was formed for each speaker by averaging the transformed vectors of that speaker. The recognition procedure was based on measuring the Euclidean distance between the test vector and the reference vectors in the transformed space; the speaker corresponding to the reference vector with the smallest distance was selected as the speaker of the test utterance. The percentage of correct identifications was found to be 97%. The results suggest that temporal variations of pitch could be used effectively for automatic speaker recognition.

Perceptual Structure of 22 Prevocalic English Consonants

Sadanand Singh, David R. Woods, and Gordon M. Becker

J. Acoust. Soc. Am. Volume 52, Issue 6B, pp. 1698-1713 (1972); (16 pages)

Online Publication Date: 12 Aug 2005

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The similarities of 22 English consonants were judged by three different methods: (1) equal‐appearing interval scale (SF), (2) magnitude estimation (ME), and (3) triadic judgments (ABX). These judgments were analyzed mainly by multidimensional (MD‐SCAL and IND‐SCAL), and multiple regression analysis techniques. In the city‐block MD‐SCAL space the SF and ME data were “best” analyzed in three dimensions and ABX data in four dimensions. In the Euclidean space the SF and ME data were analyzed in five dimensions and ABX in four. The best MD‐SCAL dimensional spaces were used to test how well the spaces were predicted by the four different feature systems, namely, (1) Miller‐Nicely (MN), (2) Singh‐Black (SB), (3) Wickelgren (W), and (4) Chomsky‐Halle (CH). The CH feature system in Euclidean space was the “best” on the criteria of consistency (Freedman's m‐ranking statistics) and prediction (tau correlation). The three data sets were also analyzed in a five‐dimensional IND‐SCAL space with the following feature interpretations: dimension 1—sibilant, dimension 2—place (front/back), dimension 3—voicing, dimension 4—plosive, and dimension 5—nasality. The feature system composed of the above features (IND‐SCAL system) was considered “best.” The features in CH system in order of perceptual importance were: (1) high; (2) voicing; (3) anterior; (4) vocalic; (5.5) nasality and strident; (7) continuant; (8) coronal; (9) low; (10) consonantal; and (11) back. The features in IND‐SCAL system in order of perceptual importance were: (1) place (front/back); (2) nasality; (3) sibilant; (4) voicing; (5) plosive. Implication of the findings of this study for phonetic theory is discussed.

Pure‐Tone Auditory Thresholds for the Carp, Cyprinis carpio

Arthur N. Popper

J. Acoust. Soc. Am. Volume 52, Issue 6B, pp. 1714-1717 (1972); (4 pages) | Cited 3 times

Online Publication Date: 12 Aug 2005

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Auditory capabilities of the Japanese carp, Cyprinis carpio, were determined using an avoidance conditioning procedure. Cyprinis could hear sounds from 50 to 3000 Hz with maximum sensitivity from 300 to 1000 Hz where the thresholds were below −34 dB (re 1 μbar). The thresholds for this species from 50 to 1500 Hz are very similar to thresholds determined for a number of other species in the same superorder of the teleosts (Ostariophysi). It is suggested that the similar hearing capabilities in these animals may be typical of all of the species of fish in this group.

Shear as a Mechanism for Sonically Induced Biological Effects

James A. Rooney

J. Acoust. Soc. Am. Volume 52, Issue 6B, pp. 1718-1724 (1972); (7 pages) | Cited 4 times

Online Publication Date: 12 Aug 2005

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By controlled irradiation of erythrocyte suspensions at 20 kHz it is demonstrated that shear associated with acoustic microstreaming can be an important mechanism for biological effects of sound. Two effective sources of acoustic microstreaming are stable oscillating gas bubbles and transversely oscillating wires. The threshold displacement amplitude for achieving critical shear can be reduced by increasing the solvent viscosity and reducing the radius of the source of acoustic streaming. The threshold stress was found to decrease by 55% or more when the sample was heated to 45°C or higher for 10 min. This suggests that synergism exists between mechanical and thermal mechanisms for sonic effects. Mass transfer associated with small‐scale acoustic streaming controls the rate of cell disruption.
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The Effects of dc Current Polarization on Cochlear Harmonics

John D. Durrant and Peter Dallos

J. Acoust. Soc. Am. Volume 52, Issue 6B, pp. 1725-1728 (1972); (4 pages)

Online Publication Date: 12 Aug 2005

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The effects of dc polarization of the cochlear partition were observed on harmonic distortion components in microphonics. The qualitative effects of negative polarization (scala vestibuli negative) were quite consistent and similar to those observed in the polarization of intermodulation distortion components. The effects of positive polarization were much more variable, but the general trends of the data suggest that when the stimulus is presented below 85–95 dB SPL, the harmonic distortion output is enhanced by both positive and negative polarizing currents. At higher intensities, these components behave much as the fundamental microphonic component. These results have been interpreted as indications that electromechanical and hydromechanical nonlinearities, respectively, dominate the distortion process over low‐ and high‐intensity ranges.

Cochlear Potential Response at the Round‐Window Membrane of the Cat—A Reply to the Comment of G. R. Price [G. R. Price, J. Acoust. Soc. Amer. 51, 2059–2061 (1972)]

T. F. Weiss and W. T. Peake

J. Acoust. Soc. Am. Volume 52, Issue 6B, pp. 1729-1734 (1972); (6 pages)

Online Publication Date: 12 Aug 2005

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G. R. Price [J. Acoust. Soc. Amer. 51, 2059–2061 (1972)] has stated that “the approximately constant relationship of cochlear microphonic output to stapes velocity noted by Weiss, Peake, and Sohmer [J. Acoust. Soc. Amer. 50, 602–615 (1971)] is probably a function of a bias introduced by the choice of electrode location, i.e., the bone near the round window.” He also argues that “the most appropriate recording site would seem to be [on] the round window.” We have measured cochlear potential responses to tones as a function of frequency with wire electrodes simultaneously on the round‐window membrane (ERW) and on the ventral surface of the petrous bone near the round window (EG). The ratio of the magnitude of these potentials, ∣ERW/EG∣, is constant (within ±2 dB) for frequencies between 400 and 20 000 Hz and depends upon frequency below 400 Hz. These results, together with those of Weiss et al., lead to the conclusion that ∣ERW/ẊS∣ is approximately constant between 400 and 10 000 Hz, where ẊS is the stapes velocity. Comparison of our measurements of ERW, with those of Price [J. Acoust. Soc. Amer. 49, 1899–1901 (1971)] reveals that the greatest differences lie in the range of frequencies between 5 and 20 kHz. The magnitude of the difference increases with frequency and is approximately 20 dB at 20 kHz. Analysis of the methods used to measure sound pressure at the tympanic membrane in these two studies indicates that the differences might result in large part from inaccuracies Price's measurements of sound pressure.
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