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Journal of the Acoustical Society of America

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Dec 1969

Volume 46, Issue 6B, pp. 1433-1590

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Relation between Sound Intensity and Amplitude of the AER at Different Stimulus Frequencies

Frank Antinoro, Paul H. Skinner, and Jacqueline J. Jones

J. Acoust. Soc. Am. Volume 46, Issue 6B, pp. 1433-1436 (1969); (4 pages) | Cited 2 times

Online Publication Date: 03 Aug 2005

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Summing computer technique was employed to study the relationship between sensation level and phons, and peak‐to‐peak (N2‐P2) voltage of the auditory evoked response at different frequencies. The relationship of the frequencies 125, 500, 1000, 2000, 4000, and 8000 Hz was studied at five intensities (20, 40, 60, 80, and 100 dB) by sensation level and by phons. There has been some controversy as to whether the power law, a straight line in double logarithmic coordinates, is a better fit than a linear relation between the voltage of the N2‐P2 peak amplitude and decibels (sensation level and phons). Our observations, however, led us to believe that the linear relation is the more accurate fit. The data also revealed a marked decrease in slope of the function from 500 to 8000 Hz. Slope ranged from 1.1 at 125 Hz to almost none (constant) at 8000 Hz. Peak‐to‐peak amplitude ranged from 3.8 μV at 20 dB to 8.9 μV at 100 dB for 500 Hz, to only 1.6 μV at 20 dB to 3.4 μV at 100 dB for 8000 Hz. The consistent growth in peak‐to‐peak amplitude with each increase in sound intensity at the low frequencies did not maintain above 2000 Hz. At 8000 Hz, for example, the average amplitude of N2‐P2 was less at 100 dB than at 80 dB. As also reported in an earlier study, a consistent decrease in the peak‐to‐peak amplitude was observed under both conditions as the frequency was increased.

Combination Tone 2fl−fh in Microphonic Potentials

Peter Dallos

J. Acoust. Soc. Am. Volume 46, Issue 6B, pp. 1437-1444 (1969); (8 pages) | Cited 1 time

Online Publication Date: 03 Aug 2005

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Microphonic potentials were recorded from guinea‐pig cochleas with differential electrodes placed into the first and third turns. Distortion components of (n+1)fl−nfh (particularly 2fl−fh) and fh±fl were studied as a function of frequency separation between the primaries and as the function of primary intensities. The conclusion is drawn that all distortion components in the cochlear microphonic behave alike, that is, there is no fundamental distinction between the properties of 2fl−fh and fh−fl. Some properties of the interference phenomenon are also examined in this study. It is suggested on the basis of the present results on distortion in cochlear microphonics and those in the literature treating subjective measures of distortion, that the role of microphonic potentials in the peripheral transduction process should be re‐examined.

Frequency Pattern of Residual Masking by Pure Tones Measured on the Békésy Audiometer

Richard H. Ehmer and Barbara J. Ehmer

J. Acoust. Soc. Am. Volume 46, Issue 6B, pp. 1445-1448 (1969); (4 pages) | Cited 2 times

Online Publication Date: 03 Aug 2005

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A Békésy audiogram for a 5‐msec tone signal repeated once per second was obtained over the frequency range 100–10 000 Hz. The audiogram was repeated with a 100‐msec masking tone preceding the signal by 10 msec. The masking tones were presented at 20 100‐dB sensation levels (SLs). The results show that 250 and 500 Hz produce no masking at 20 dB, but the greatest over‐all masking, without sharply defined maxima, occurs at higher SLs. Maskers of 1000, 2000, and 4000 Hz produce masking at the 20‐dB level. At the low levels, there is a clear peak at the masking frequency; but as the masker level is raised, this peak begins to shift to increasingly higher frequencies, although it never reaches the second harmonic.

Temporary Threshold Shifts Following Pulsed Monaural and Alternate Binaural Exposure

J. M. Guiot

J. Acoust. Soc. Am. Volume 46, Issue 6B, pp. 1449-1451 (1969); (3 pages)

Online Publication Date: 03 Aug 2005

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The temporary threshold shifts (TTS) produced by exposure to pulsed monaural and pulsed alternate binaural high‐intensity stimuli (105 dB sensation level, 1 kHz) were compared in 7 subjects (6 male, 1 female). All subjects showed greater TTS for monaural exposures than for binaural, except in three cases out of 21 (six experimental conditions). However, monaural and binaural TTS were found to be significantly different (0.01 level) in only one instance of the three paired conditions.

A Direct Comparison between Lateralization and Detection under Conditions of Antiphasic Masking

Ervin R. Hafter, Walter T. Bourbon, Anne S. Blocker, and Ann Tucker

J. Acoust. Soc. Am. Volume 46, Issue 6B, pp. 1452-1457 (1969); (6 pages) | Cited 6 times

Online Publication Date: 03 Aug 2005

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In order to compare lateralization and the detection of noise‐masked signals under conditions of antiphasic masking, subjects were instructed to indicate the lateral displacement of signals presented at five levels of signal‐to‐noise ratio. The signals were 500‐Hz 100‐msec bursts of tone heard in a wide‐band noise mask. A “likelihood ratio” analysis of lateralization data allowed a direct comparison between detection based on lateralized differences and detection obtained in a standard two‐interval forced‐choice detection experiment. It was found that the measure of detection based on lateralization is nearly the same as that actually obtained in the conventional detection experiment.

Practice Effects and Signal Detection Indices in an Auditory Vigilance Task

Jimmy L. Hatfield and David R. Soderquist

J. Acoust. Soc. Am. Volume 46, Issue 6B, pp. 1458-1463 (1969); (6 pages)

Online Publication Date: 03 Aug 2005

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Performance of nine subjects was investigated over ten 90‐min vigilance sessions. Trends in performance over and within sessions were examined in terms of three dependent measures: (a) correct detections, (b) errors of commission, and (c) theory of signal detectability (TSD) indices d′ and β. The results indicate that: (1) TSD accounts for performance over sessions but is inadequate in accounting for within‐sessions decrements unless basic tenets of the theory are altered. (2) Performance decreases within sessions for the first 30 min, regardless of practice. (3) Within sessions decrements may be accounted for by assuming either a decrease in the observer's activation level, a distracted mode of observing, or both.

Interaural Time and Amplitude jnds for a 500‐Hz Tone

R. M. Hershkowitz and N. I. Durlach

J. Acoust. Soc. Am. Volume 46, Issue 6B, pp. 1464-1467 (1969); (4 pages) | Cited 13 times

Online Publication Date: 03 Aug 2005

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Preliminary experiments were performed on the discrimination of interaural time and the discrimination of interaural amplitude for lateralization images both on and off the midline, using a common set of subjects and a common experimental configuration. The results are compared with some previous work on interaural discrimination and time‐intensity trading and with the prediction of the EC model relating interaural time discrimination to interaural amplitude discrimination.

Modulated Frequency Discrimination in Relationship to Age and Musical Training

Clifford K. Madsen, Frank A. Edmonson, III, and Charles H. Madsen, Jr.

J. Acoust. Soc. Am. Volume 46, Issue 6B, pp. 1468-1472 (1969); (5 pages)

Online Publication Date: 03 Aug 2005

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The purpose of the study was to test auditory discrimination of a modulated frequency. Two hundred subjects participated in the study representing second graders, fifth graders, eighth graders, eleventh graders, college non‐music majors (juniors), junior music majors, graduate music students, and School of Music faculty, respectively. The stimulus frequency was F# (369.99 Hz), which was presented to subjects individually in 15 randomized 30‐sec trials in three catagories: (1) without frequency alteration; (2) ascendingly; and (3) descendingly. Modulation for the ascending and descending tones was 2 cents/sec during the last 25 sec of the stimulus tone. Results of the study indicate that: (1) Auditory discrimination is partially a function of age as well as of music training; (2) comparatively, younger subjects respond to tonal stimuli “incorrectly and sharp” while older subjects evidence “better discrimination while demonstrating a proclivity toward flatness”; (3) perception of the modulated frequency is best during the first 5 sec (10 cents) of frequency change; and (4) auditory tests that attempt to assess discrimination should control for guessing as well as for directional, i.e., up‐down, propensities.

The FROC Curve: A Representation of the Observer's Performance for the Method of Free Response

Harold Miller

J. Acoust. Soc. Am. Volume 46, Issue 6B, pp. 1473-1476 (1969); (4 pages) | Cited 5 times

Online Publication Date: 03 Aug 2005

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In a YES‐NO signal detection task, the observer's performance can be represented by an ROC curve. In a free‐response task, an ROC curve cannot be plotted because the observation interval is not defined. However, if the responses can be partitioned into hits and false alarms, then the observer's performance can be represented by an FROC curve, which possesses many of the properties of an ROC curve. FROC curves are obtained from a single observer in a vigilance task to demonstrate its use.

Limits for the Detection of Binaural Beats

David R. Perrott and Michael A. Nelson

J. Acoust. Soc. Am. Volume 46, Issue 6B, pp. 1477-1481 (1969); (5 pages) | Cited 4 times

Online Publication Date: 03 Aug 2005

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This study investigates the probability of detecting binaural beats as a function of the frequency of the standard signal used (f1) and of the dichotic frequency difference (∣f1−f2∣). The present findings indicate that the upper frequency limit for the perception of binaural beats depends upon the dichotic frequency differences employed, the psychophysical procedure used, and the criteria for a beat threshold. The probability of beat detections was maximal at 500 Hz, and decreased as frequency increased up to 1500 Hz. No reliable pattern of beat detections was observed above 1500 Hz. Binaural beats were obtained with both “fused” and “nonfused” dichotically presented signals. Implications for a general model were discussed.

Interaural Intensity Difference for Intracranial Lateralization

Marilyn L. Pinheiro and Henry Tobin

J. Acoust. Soc. Am. Volume 46, Issue 6B, pp. 1482-1487 (1969); (6 pages) | Cited 1 time

Online Publication Date: 03 Aug 2005

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The interaural intensity difference (IID) for intracranial lateralization of white‐noise bursts was investigated in 17 normal subjects, in 17 subjects with high‐frequency sensorineural hearing losses, and in 17 subjects with predominantly unilateral cerebral lesions. Broad‐band‐ and low‐pass filtered‐noise bursts with durations of 76 msec and 506 msec and a fast rise time of 10 msec were used for the dichotic signals. These were presented relative to the hearing sensitivity in each ear. There were no statistically significant differences between normal and sensorineural subjects except for the filtered noise condition, which resulted in a slightly but significantly greater IID for subjects with hearing losses. In subjects with cerebral lesions, the IID for the ear contralateral to the lesion was much smaller than the IID for normal or sensorineural ears, while the IID for lateralization to the ear ipsilateral to the lesion was slightly larger than the normal IID. It was found that the model for neural interaction in stimulus lateralization that von Békésy developed on the surface of the skin could be applied to the auditory phenomenon of sound lateralization.

Relation between Critical Bands in Hearing and the Phase Characteristics of Cubic Difference Tones

M. R. Schroeder

J. Acoust. Soc. Am. Volume 46, Issue 6B, pp. 1488-1492 (1969); (5 pages) | Cited 2 times

Online Publication Date: 03 Aug 2005

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The measured amplitude and phase characteristics of aural cubic difference tones are difficult to account for solely by known mechanical processes in the ear. The frequency selectivity implied by these characteristics considerably exceeds that of the middle and inner ears, even when the selectivity of the basilar membrane is augmented by a traveling‐wave model for nonlinear distortion components. On the other hand, the frequency selectivity implied by the phase characteristics of the cubic difference tone is found to correspond closely to the well‐known critical bandwidths of hearing. Thus, the sharpening mechanism responsible for the formation of the critical bands may also be responsible for the formation and perception of cubic difference tones. New phase measurements, with a well‐defined phase reference, show that the auditory nonlinearity giving rise to cubic difference tones must be an amplitude‐limiting nonlinearity if it occurs in an excitatory channel (or an amplitude‐expanding one if it is located primarily in an inhibitory pathway).

Recognition of Repeated Patterns: A Study of Short‐Term Auditory Storage

Earl D. Schubert and Roger A. West

J. Acoust. Soc. Am. Volume 46, Issue 6B, pp. 1493-1501 (1969); (9 pages)

Online Publication Date: 03 Aug 2005

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The parameters of waveform that enable listeners to recognize repetition of patterns within a signal were explored by using four types of waveform called random‐amplitude constant‐period, constant‐amplitude random‐period, random‐amplitude random‐period cophasic, and random‐amplitude random‐period antiphasic. The measure used for comparison was the number of repetitions per signal required to differentiate signals containing repetitions from random waveforms that did not contain repetitions. In the first experiment reported, the subject's performance was kept at 75% correct differentiation by varying the number of repetitions per signal. The comparisons were made among all four types of waveforms at each of three sensation levels: 20, 50, and 80 dB. Signals with zero‐crossing information (random period) and signals of medium sensation level appear best for recognition of the repetition of patterns. In the second experiment, the same type of signals were high‐pass or low‐pass filtered, and similar comparisons were run. Although absolute comparisons were not possible, it appears that high‐frequency information is more useful than low to the auditory system in identifying the repetitions within signals. A third experiment explored the possibility that one type of signal waveform is more readily learned than another. To make the task more difficult, segments of either noise or silence were inserted between the repetitions of the patterns, and were introduced with the same spacing into the nonrepeated waveforms. Repetition of pattern was still too easily recognized by the subjects, and no evidence of any difference in rate of learning to recognize patterns was found for the different types of waveform.

Hearing Threshold and Ear‐Canal Pressure Levels with Varying Acoustic Field

E. A. G. Shaw

J. Acoust. Soc. Am. Volume 46, Issue 6B, pp. 1502-1514 (1969); (13 pages)

Online Publication Date: 03 Aug 2005

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A well‐damped circumaural enclosure is equipped with five independent acoustic driver units located at cardinal positions. The acoustic field near the external ear may thus be varied in a manner corresponding to angle of incidence. The acoustic pressure at a well‐defined position at the ear‐canal entrance is measured with a probe tube passing under the circumaural cushion. With each subject and frequency, the driver voltage level at hearing threshold LC and the ear‐canal response REC are determined for each driver unit in turn. A double series of measurements has been made with six subjects from 1–12 kHz and three to six subjects from 13 to 16 kHz at 1‐kHz intervals. The ear‐canal pressure level at hearing threshold LE is found to be virtually independent of the acoustic‐field geometry up to 12 kHz. Changes in LC and REC observed after a one‐week interval can be related to three independent mechanisms: (1) changes in subject hearing sensitivity, (2) changes in coupling between probe‐tube orifice and ear‐canal wave pattern, and (3) changes in coupling between the various driver units and the ear canal. Changes in subject sensitivity are approximately 2 dB, independent of frequency, up to at least 13 kHz. Probe coupling changes are small below 9 kHz. At the higher frequencies, driver coupling changes are occasionally very large (more than 20 dB in extreme cases), generally much greater than changes in subject sensitivity, and dependent on frequency in a distinctive manner related to the geometry of the sound field.

Effect of Circumaural Earphone Cushions on Threshold Sensitivity for Speech

Charles Speaks

J. Acoust. Soc. Am. Volume 46, Issue 6B, pp. 1515-1518 (1969); (4 pages)

Online Publication Date: 03 Aug 2005

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Threshold sensitivity measures for speech were obtained with a TDH‐39 earphone housed in both an MX 41/AR supraaural cushion and a CZW‐6 circumaural cushion. The shift in threshold sensitivity for the CZW 6 cushion relative to the MX 41/AR cushion was approximately −3.5 dB. The shift in threshold seemed reasonably constant for three separate tests of speech intelligibility. Corrections for threshold sensitivity for speech cannot be inferred easily from similar data obtained in response to pure tones.

Monaural Detection with Contralateral Cue (MDCC). I. Better than Energy Detector Performance by Human Observers

M. M. Taylor and S. M. Forbes

J. Acoust. Soc. Am. Volume 46, Issue 6B, pp. 1519-1526 (1969); (8 pages) | Cited 4 times

Online Publication Date: 03 Aug 2005

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Human observers were given a monaural detection task. Information in the form of a “cue” derived in some manner from the signal was presented simultaneously to the other ear. The signal and the cue always had the same timing and spectral characteristics and were samples of low‐pass filtered noise. The cue was always presented in each possible signal interval, whether or not the signal itself was presented. Different cue conditions were used, in which the cue bore different amounts of information relevant to the signal. When the cue and signal were independently generated but identically timed and filtered, performance was indistinguishable from the no‐cue control condition, and was like that of an inefficient energy detector using a filter matched to the signal bandwidth. When the cue was an identical replica of the signal, performance was much better than that of an ideal energy detector and, for bandwidths less than 1600 Hz, approached that of an equally inefficient likelihood‐ratio detector for signal known exactly. Efficiency in both cases was of the order of 25%–30%. When the cue was derived from the signal but passed through a wide‐band 90° phase shifter, it provided an intermediate amount of information, and detection performance was also at an intermediate level. The results are taken to show that when relevant information is available to the detection mechanism, it can be used; and that the usual finding of energy‐detector like monaural performance is due to lack of more precise information about the signal at the detector.

Free‐Field Calibration of Earphones

Edgar Villchur

J. Acoust. Soc. Am. Volume 46, Issue 6B, pp. 1527-1534 (1969); (8 pages) | Cited 2 times

Online Publication Date: 03 Aug 2005

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Probe‐microphone measurements of the real‐ear response of an earphone are subject to inherent problems of interpretation. The cushion‐enclosed sound field is homogeneous only in the frequency region below 1 kHz, and measurements outside this band can differ by more than 15 dB from one probe position to another. Probe measurements at the earphone diaphragm do not provide enough information on earphone response, because the earphone can create or modify resonances in the outer ear that affect the pressure delivered to the eardrum. Measurements at the canal entrance provide too much information, because they include pinna gain characteristics that are not functions of earphone performance. In the present experiments, the response of an earphone is derived by subtracting, from earphone‐induced sound pressures at the eardrum, the sound pressures produced at the same point by a loudspeaker that the pinna faces. The speaker is used to establish a reference of outer ear acoustic gain before disturbance by the earphone, less the effects of head diffraction. The eardrum position was selected for the probe‐tube measurements after a preliminary experiment showed that a supraaural earphone can affect ear canal gain by constricting the canal entrance and lowering the canal's resonant frequency. The derived response curves were in agreement with earphone frequency‐response data derived from subjective judgments by the corresponding subjects.

Effect of Acoustic Cues in Fricatives on Perceptual Confusions in Preschool Children

Mary Skeel Abbs and Fred D. Minifie

J. Acoust. Soc. Am. Volume 46, Issue 6B, pp. 1535-1542 (1969); (8 pages)

Online Publication Date: 03 Aug 2005

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Seventeen preschool children were tested to determine their ability to discriminate among the fricatives /s, z, f, v, θ, and ð/presented in consonant‐vowel (CV) and vowel‐consonant (VC) combinations with each of three vowels/ɑ, i, aɪ/. Syllable pairs were presented to the children for each possible fricative comparison, with consonant position and vowel being the same in any one pair. The stimulus tape was analyzed to determine durations of the consonants and vowels, peak amplitude of the fricatives, and center frequency and bandwidth of the resonance curves of each of the fricatives. The contribution of these acoustic cues to discrimination among the fricatives was evaluated. The voiced‐unvoiced distinction appears to be facilitated in VC syllables by the ratio of consonant duration to vowel duration. The fricatives /s/ and /z/ are set apart from the other fricatives by their high intensity, high frequency, and shorter spectrums, thus making discriminations between /s/ or /z/ and the other fricatives considerably easier than discriminations among /f/, /v/, /θ/, and /ð/. The highest discrimination error rates are observed in the pairs /f‐θ/ and /v‐ð/, where there are neither voicing differences nor significant spectral differences between the two fricatives. Considerably lower discrimination error rates are observed when either voicing differences are present between two fricatives or there are significant spectral differences.

Vocal Loudness and Effort in Continuous Speech

John F. Brandt, Kenneth F. Ruder, and Thomas Shipp, Jr.

J. Acoust. Soc. Am. Volume 46, Issue 6B, pp. 1543-1548 (1969); (6 pages) | Cited 3 times

Online Publication Date: 03 Aug 2005

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The direct‐magnitude‐estimation scaling technique was used to investigate listener perception of vocal loudness and vocal effort of a continuous speech sample. Three experimental conditions were developed that represented (1) normal changes in loudness and effort, (2) intensity held constant and effort varied, and (3) intensity varied and effort constant. The speech samples were judged by 20 listeners on the magnitudes of loudness and of the amount of effort used by the speaker during phonation. Exponents of the loudness and effort functions (1.12 and 0.57, respectively) suggest that vocal loudness and effort are different percepts of the listener. An examination of the acoustic stimuli suggests that a systematic increase in stimulus bandwidth with an increase in vocal intensity may be related to judgments of both loudness and effort.

Vocal‐Tract Characteristics of the Stop Cognates

R. D. Kent and K. L. Moll

J. Acoust. Soc. Am. Volume 46, Issue 6B, pp. 1549-1555 (1969); (7 pages) | Cited 4 times

Online Publication Date: 03 Aug 2005

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Cinefluorographic films and throat microphone recordings were obtained from three male speakers for 18 pairs of utterances in which one member of a pair differed from the other only in a stop cognate, i.e., /p, t, k/:/b, d, g/. The data reveal that, although stop cognates are similar in the characteristics of the constrictory articulation, the voiced stop is produced with a larger supraglottal volume than its voiceless cognate. The volume differences are caused by a lengthening and expansion of the oropharynx during voiced stops. These processes, which probably satisfy the aerodynamic requirements of voicing, are interpreted to be the results of muscular action rather than passive responses of the vocal tract. Further observations concern the articulatory dynamics of consonant production and may be relevant to the description of neuromotor commands in speech production.

Loudness Judgments of Speech and Nonspeech Stimuli

Maurice I. Mendel, Harvey M. Sussman, Richard M. Merson, Margaret Ann Naeser, and Fred D. Minifie

J. Acoust. Soc. Am. Volume 46, Issue 6B, pp. 1556-1561 (1969); (6 pages) | Cited 2 times

Online Publication Date: 03 Aug 2005

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Listener's numerical estimations of loudness were compared for three sets of stimuli. The exponential loudness values for machine‐generated signals varied from 0.80 to 0.86. The loudness functions for various speech conditions, recorded at normal effort levels and played back at seven different sound‐pressure levels, varied from 0.74 to 0.84. The loudness functions of autophonically varied speech levels ranged from 0.86 to 1.20. Listeners in this study tented to respond differently to speaker‐varied speech signal levels than to the electronically varied speech signals. Therefore, it is assumed that listener loudness judgments of speaker‐varied speech levels are related to acoustic cues that vary as a function of amount of effort used by the speaker.

Perception of Vocoder Speech Processed by Pattern Matching

Caldwell P. Smith

J. Acoust. Soc. Am. Volume 46, Issue 6B, pp. 1562-1571 (1969); (10 pages)

Online Publication Date: 03 Aug 2005

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Tests were conducted to assess speech discriminability with spectrum data from a channel vocoder compressed to values from 450 to 600 bits/sec by spectrum pattern matching, in comparison with speech discriminability for the same system operating with conventional pulse code modulation to encode spectrum data at rates from 900 to 2700 bits/sec. The pattern‐matching method, in which each spectrum sample was processed by selecting and substituting a nearest neighbor pattern from a fixed digital memory, was tested in 12 configurations, ranging from 497 patterns (328 voiced, 169 unvoiced) to 3996 patterns (2893 voiced, 1103 unvoiced) with input speech consisting of recordings of eight scramblings of the 448‐word diagnostic rhyme test described by Voiers. Tests with listening crews confirmed that pattern matching compares favorably with conventional 2400 bits/sec vocoder art in terms of consonant discriminability, with mean scores obtained with the 12 configurations of the pattern memory table as follows: sibilation, 97.9; nasality 95.1; compactness 93.0; voicing 88.4; graveness 86.7; sustention 67.0. The six features showed varying degrees of sensitivity to the composition and number of stored patterns. Total intelligibility scores ranged from 82.6 (using a total of 497 patterns and monotone pitch) up to 91.9 (using 3996 patterns and normal pitch at 300 bits/sec). Comparative data were plotted for feature discriminability versus spectrum data rate for pattern matching and for conventional pulse‐code modulation.

Acoustico‐Lateralis System of Fishes: Tests of Pressure and Particle‐Velocity Sensitivity in Grunts, Haemulon sciurus and Haemulon parrai

Phyllis H. Cahn, William Siler, and Jerome Wodinsky

J. Acoust. Soc. Am. Volume 46, Issue 6B, pp. 1572-1578 (1969); (7 pages) | Cited 4 times

Online Publication Date: 03 Aug 2005

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Avoidance‐conditioning studies on young grunts, the bluestriped Haemulon sciurus, and the sailor's choice, H. parrai, were carried out in a calibrated tubular plexiglas vessel, where the fish were subjected to either farfield conditions of sound, where sound pressure and particle velocity were equal, or to a nearfield situation, where the velocity exceeded the pressure by up to 35 dB. At 400 Hz, the fish were found to be sensitive to pressure only, at threshold levels. At 200 and 100 Hz, the threshold patterns were more complex, and the fish responded to either pressure or velocity irrespective of a near‐ or farfield pressure‐velocity relationship, but probably dependent on previous conditioning and starting intensities. Our data suggest that as frequency is lowered, velocity sensitivity increases, and there appears to be a weak coupling of the pressure‐ and velocity‐detection systems. This weak coupling is surprising view of the close relationship between the ear and the lateral‐line sensory systems, the two receptors here involved. Studies are in progress to learn more about the various aspects of the low‐frequency response.
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Proposed Explanation of Synchrony of Auditory‐Nerve Impulses to Combination Tones

E. de Boer, P. Kuyper, and G. Smoorenburg

J. Acoust. Soc. Am. Volume 46, Issue 6B, pp. 1579-1581 (1969); (3 pages)

Online Publication Date: 03 Aug 2005

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When the acoustic stimulus consists of two sinusoidal components (frequencies f1 and f2), the impulses of a single auditory‐nerve fiber can show partial synchrony with either of these components (provided the frequencies stay below approx 5 kHz). Often a synchrony with an externally generated combination tone of frequency 2f1−f2 can be detected as well. It is shown in this letter than such a behavior is a logical consequence of the assumption that nerve impulses are elicited at the peaks of the stimulus waveform. In addition, it is demonstrated that only special combination tones will show this phenomenon. Many of the experimental results on this type of synchrony can be explained in this way. It is thus not necessary to assume that a special physiological mechanism is responsible for the observed synchrony per se. But deviations from the basic properties derived here should be observed closely, because these do give useful indications about cochlear physiology.

Some Pitfalls in Adaptive Testing: Comments on “Temporal Integration and Periodicity Pitch” [R. A. Campbell and S. A. Counter, J. Acoust. Soc. Amer. 45, 691–693 (1969)[

C. Douglas Creelman and M. M. Taylor

J. Acoust. Soc. Am. Volume 46, Issue 6B, pp. 1581-1582 (1969); (2 pages)

Online Publication Date: 03 Aug 2005

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Campbell and Counter (1969) measured “thresholds” for various short durations of low‐frequency sinusoidal signals. The adaptive psychophysical procedure they used is shown to yield uninterpretable results; values they report can represent a wide range of performance levels. In this note, we take Campbell's and Counter's study as an example of the methodological traps in seemingly straightforward testing methods.
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