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Nov 1981

Volume 70, Issue S1, pp. S1-S109

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back to top Session GG: Psychological Acoustics V and Physiological Acoustics V: Middle Ear, Testing, and Evoked Responses
Contributed Papers
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The influence of signal spectrum on click elicited evoked responses (A)

Jeffrey Owen, Craig Champlin, and Randy Laskowski

J. Acoust. Soc. Am. Volume 70, Issue S1, pp. S70-S70 (1981); (1 page)

Online Publication Date: 12 Aug 2005

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Click elicited evoked responses have gained widespread clinical use as a measure of the neurological and audiological integrity of the auditory brain stem structures. Typically, the clicks are presented at various intensity levels and the elicited responses are compared interaurally as well as with established norms. This study was conducted to determine the influence of the spectrum of the transduced click on the latency and amplitude characteristics of the averaged response elicited at various intensity levels [Clicks (100‐μs square waves) were presented monaurally at 50, 60, 70, and 80 dB nHL]. Spectral analysis of the transduced signals indicated that the frequency response characteristics of the earphones significantly influenced the bandwidth of the signal. Furthermore, one earphone introduced a significant amount of intermodulation distortion into the transduced signal. The influence of the transduced signal on the inter‐ and intrasubject characteristics of the evoked potential will be presented.
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High‐frequency contributions to the SN10 response (A)

Craig A. Champlin, Randy Laskowski, and Jeffrey H. Owen

J. Acoust. Soc. Am. Volume 70, Issue S1, pp. S70-S70 (1981); (1 page)

Online Publication Date: 12 Aug 2005

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The slow negative brainstem response (SN10) to tone‐burst stimuli has been used to assess peripheral auditory function. When basilar membrane displacement and physiological tuning curves are considered, basal contributions of frequencies above the stimulus frequency are suggested. This study examined the SN10 in response to monaural stimulation at the center frequencies of 1000 and 2000 Hz. Signals were presented at 50 dB nHL. Two conditions were utilized: (1) SN10 responses were obtained at the beginning and end of each session without masking, (2) A series of ipsilaterally presented high‐pass noise masking conditions were administered between the nonmasking conditions. The slope of the filter was also manipulated. The amplitude, latency, and morphology of the SN10 were evaluated for each condition.
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Further observations on the effects of broadband noise on the BER (A)

Bob Burkard and Kurt Hecox

J. Acoust. Soc. Am. Volume 70, Issue S1, pp. S70-S70 (1981); (1 page)

Online Publication Date: 12 Aug 2005

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At a previous meeting of the Society [Burkard et al., J. Acoust. Soc. Am. Suppl. 1 69, S85 (1981)] we described the effect of broadband noise on the BER as a function of click intensity, rate, and noise level. At that time the possibility of nonadditivity of the effect of stimulus rate and noise on wave V latency was raised, leading to a more detailed analysis of the effects of noise on the time course of rate effects. An adaptation paradigm was used in which the latency of the wave V response to the first click in the train was compared to subsequent responses. Less adaptation was observed at noise levels which influenced wave V behavior. This nonadditivity suggests that the effects of broadband noise and stimulus repetition rate may be mediated by overlapping mechanisms. This supposition is supported by the differences in the time course of adaptation seen in noise versus no‐noise conditions. The effects of broadband noise on responses evoked by tone‐burst stimuli will also be described. [Work supported by NIH.]
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Frequency‐specific effects of stimulus rise‐fall time on the human BAEP (A)

Don Deegan and Kurt Hecox

J. Acoust. Soc. Am. Volume 70, Issue S1, pp. S70-S70 (1981); (1 page)

Online Publication Date: 12 Aug 2005

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High‐pass masking was used to determine the effect of varying rise‐fall time (0, 1, 2, and 5 ms) on the frequency specificity of the brainstem auditory evoked potential (BAEP) to 50 dB nHL noise bursts. The latencies and amplitudes of frequency‐specific waveforms were obtained by subtractive masking [Don and Eggermont, J. Acoust, Soc. Am. 63, 1084–1092 (1978)]. Results showed increasing latency and decreasing amplitude of wave V with decreasing frequency band. Increasing rise‐fall time within a frequency band prolonged latencies and decreased amplitudes. There was a convergence of latency values between rise‐fall times as frequency band decreased consistent with a place mechanism. However, divergent latency differences between rise‐fall times but within frequency bands suggests that additional mechanisms may be operative. Amplitude effects were complex but there was a suggestion that increasing rise‐fall time results in an apical shift in the generation of the BAEP. Traveling‐wave velocities calculated using previously published techniques and the latencies described herein are in good agreement with prior estimates in the human. [Work supported by NIH.]
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Some properties of an auditory evoked response with a latency range of 10–18 ms (A)

Alan J. Klein

J. Acoust. Soc. Am. Volume 70, Issue S1, pp. S70-S71 (1981); (2 pages)

Online Publication Date: 12 Aug 2005

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A slow‐wave evoked response, possibly a late component of the brainstem response, can be used to estimate hearing sensitivity to low‐frequency stimuli [T. Suzuki, et al., Scand. Audiol. 6, 51–56, (1977)]. On human subjects with normal hearing psychophysical pure tone and tone pip thresholds were compared with evoked response thresholds. Frequency specificity of the response was measured with a simultaneous‐masking tuning curve paradigm. All tone pips (0.25, 0.50, 1.0, 2.0, 4.0 kHz) had a rise‐fall time of 3.0 ms with no plateau and were presented at 40/s. Mean audibility curves for pure tones and tone pips were parallel. The tone pip curve was displaced above the pure tone one by 5–10 dB. The evoked response threshold curve paralleled the psychophysical curves but was displaced above the tone pip curve by 15–20 dB. Tuning curves to signals at 0.5, 1.0, 2.0, and 4.0 kHz suggest that this evoked response is frequency specific at least up to 60 dB sensation level. Tuning curves to signals at 250 Hz had tips in the 350–450 Hz region. In some subjects, evoked response threshold increased by as much as 20 dB during sleep. [Supported by NIEHS].
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Electrophysiological responses of hearing‐impaired subjects to speech stimuli (A)

Samuel B. Polen, R. Patrick Greenwood, and Carol Yoneda

J. Acoust. Soc. Am. Volume 70, Issue S1, pp. S71-S71 (1981); (1 page)

Online Publication Date: 12 Aug 2005

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It has been demonstrated [Polen et al. (1981)] that certain unique electrophysiological phenomena may occur in response to the presentation of target phonemes within an orienting response paradigm. Subsequent to these findings, it was questioned whether such responses would be altered due to the presence of hearing loss. This study investigated the characteristics of late components of the averaged electrophysiological response to speech stimuli for sensorineural hearing impaired subjects. Evoked potentials were obtained in response to stimuli presented within an orienting response paradigm. The stimuli consisted of target phonemes interspersed at random intervals in the “background” of a repeating, contrastive phoneme. The averaged waveforms obtained were further subjected to Fourier analysis, resulting in discrete energy spectra of from 0 to 20 Hz. It was found that subjects with severe hearing losses in the range of 1.5–8 kHz responded with greatest energy in the 8–11 Hz component range, while those with relatively better hearing through 2 kHz tended to demonstrate greater energy for the 1–5 Hz components.
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Asymmetries in the binaural interaction of the auditory brainstem response (A)

C. Berlin, P. Allen, and K. Parrish

J. Acoust. Soc. Am. Volume 70, Issue S1, pp. S71-S71 (1981); (1 page)

Online Publication Date: 12 Aug 2005

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Twenty normal listeners generated auditory brainstem responses to simultaneous condensation 100 μs transients of 70 dB HLN to the left ear, right ear, and finally under binaural conditions. ABR was recorded simultaneously through two matched preamplifiers with vertex as a G1 electrode, the respective ear lobes as G2 for each preamplifier, and the nasion as a ground. Because of the recording montage and because, during binaural stimulation both right and left preamplifiers were active, it was possible to study asymmetries in the following five relationships: (1)[BinR − BinL], (2) [BinR + BinL] −ϵ[RI + RC) or (LI + LC), (3) [BinR + BinL] −ϵ[RI + LC) or (LI + RC)], (4) [BinR + BinL]/2 −ϵ[LI + LC) or ϵ(LI + LC) or ϵ(RI + RC)], (5) [BinR + BinL]/2 −ϵ[(LI + RC) or ϵ(RI + LC)], in which R = biological data from right amplifier, L = biological data from left preamplifier, I = ipsilateral stimulation, C = contralateral stimulation and Bin = binaural stimulation. Data support, Decker and Howe [J. Acoust. Soc. Am. 69, 1084 (1981)] in that either the left or right ear usually dominates the binaural interaction, but also show that recording montage and binaural stimulation conditions lead to other forms of recordable asymmetries. [Work supported by NINCDS 11647.]
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Phasor admittance measurements of the middle ear (A)

Mark E. Lutman

J. Acoust. Soc. Am. Volume 70, Issue S1, pp. S71-S71 (1981); (1 page)

Online Publication Date: 12 Aug 2005

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Conventional techniques for the measurement of the acoustic admittance of the middle ear are heavily dependent upon the mobility of the most flaccid parts of the tympanic membrane and relatively insensitive to abnormalities of the ossicular chain. This paper describes a method which has been developed to characterize the vibratory properties of the tympanic membrane and the ossicular chain separately. The technique is based on the analysis of trajectories traced by the middle‐ear admittance phasor as either the external ear canal pressure, or the stapedius muscle tension, is modified. Consequently, the tympanic membrane and ossicular chain are each characterised by means of a natural frequency and damping ratio. Normative data are presented from 68 ears screened for middle‐ear disease. The results indicate that the two measures are each relatively consistent between subjects, yet the two measures within subjects are independent of one another. Thus they provide tractable measures of middle‐ear status.
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Effects of linear frequency modulated ramps on stapedius muscle reflex (SMR) in children (A)

M. L. Lenhardt

J. Acoust. Soc. Am. Volume 70, Issue S1, pp. S71-S71 (1981); (1 page)

Online Publication Date: 12 Aug 2005

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Thirty 6‐year‐old children with normal hearing, speech discrimination, and SMRs to tones and noise were given FM stimulation. A 2000‐Hz tone was presented at 15 dB + SMR threshold until SMR decayed. The frequency was either modulated upward (to 40000 Hz) or downward (to 1000 Hz) in 100 ms for a series of intensity steps until a full contralateral SM contraction was recorded. Decay of the tonal SMR preceded FM testing at each step. The reciprocal to the 2000‐Hz rising ramp was also employed and presented re the 4000‐Hz tonal SMR. Ramps were filtered to equate intensity. All FM ramps induced a reactivation of the SMR. When equated at the percent of full contraction the 2000‐Hz rising ramp had a larger dynamic range than either the falling or reciprocal conditions. The SMR waveform morphology varied with sound intensity. At high levels the SMR onset and offset was fast and the amplitude high, but as the sound intensity decreased onset and offset times increased and amplitudes reduced resulting in a broadening of the waveform.
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Perstimulatory adaptation of acoustic reflex in normally hearing subjects (A)

David J. Thompson and H. Stephen Hawkins

J. Acoust. Soc. Am. Volume 70, Issue S1, pp. S71-S72 (1981); (2 pages)

Online Publication Date: 12 Aug 2005

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This was an investigation of acoustic‐reflex adaptation in ten adults in each age decade between 20 and 79 years. Reflex‐activating stimuli, presented by earphone to the ear contralateral to the acoustic‐immittance probe, were four tones (0.5, 1.0, 2.0, and 4.0 kHz) and two filtered noises. Sound pressure levels were +5, +10, +15, and +20 dB re: acoustic‐reflex threshold. Stimulus duration was 60 s. Reflex responses were measured with both components of aural acoustic admittance. Custom software was written for automated digitization, storage, quantification, and plotting of the responses. Statistical analyses of conductance and susceptance data included static acoustic admittance, acoustic‐reflex threshold. maximum amplitude of reflex, rate of adaptation, and shift of baseline during reflex activation. Adaptation rate was highest for the 4.0‐ and 2.0‐kHz activators and varied with stimulus level. Comparison of multiple regressions revealed age‐related trends in measures of adaptation. [Work supported by VA‐RER&D.]
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An ear simulator study of resonances in occluded human ear canals (A)

Samuel Gilman

J. Acoust. Soc. Am. Volume 70, Issue S1, pp. S72-S72 (1981); (1 page)

Online Publication Date: 12 Aug 2005

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The frequencies at which resonances occur in an occluded ear canal were measured over a range from 100 Hz to 20 kHz using ear simulators (Zwislocki, 1970) and a constant volume displacement source (B&K 4134 microphone operated with zero bias). Three variables were introduced: earmold bore, ear‐canal length, and eardrum impedance. Mid‐frequency resonance frequencies (1000 to 3000 Hz) were found to be primarily functions of the reactance of the load presented to the source by the occluded simulator. Resonances at frequencies between 9 and 13 kHz were related to ear canal length. Ear canal volume or diameter affected resonances on the basis of their contribution to the input impedance of the simulators. Major resonances also occurred at frequencies related principally to the source‐to‐eardrum distance (independent of impedance).
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Examination effects on ac thresholds (A)

Alex F. Roche, Debabrata Mukherjee, and W. Cameron Chumlea

J. Acoust. Soc. Am. Volume 70, Issue S1, pp. S72-S72 (1981); (1 page)

Online Publication Date: 12 Aug 2005

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Serial ac pure‐tone thresholds have been recorded serially at 6‐month intervals in 261 normal children aged 6 to 18 years at their first examinations. Data from 1802 examinations have been analyzed by a regression model fitted to all the data, for each frequency in each ear, within sex after excluding examinations at which pathological changes were present. The regression of thresholds on examination order, after removing age effects, shows a significant linear effect but no significant quadratic effect. The examination effect does not differ significantly by sex or ear but varies significantly by frequency (p < 0.004) as shown by an analysis of variance with balanced design and adjustments for sex and ear effects. The examination effects are significantly greater at 4 and 6 kHz (about 0.7 dB/examination) than at 0.5, 1, and 2 kHz (about 0.4 dB/examination). The possibility of separating examination effects due to the influence of habituation, movivation, and changes in noise exposure will be discussed in addition to the relevance of the present findings to the assessment of intervention programs. [Work supported by Contract No. F33615‐81‐C‐0516 from the USAF and EPA.]
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