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Dec 1986

Volume 80, Issue S1, pp. S1-S128

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back to top Session W. Psychological and Physiological Acoustics III: Auditory Evoked Potentials and Otoacoustic Emissions
Contributed Papers
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Effects of relative starting phase and frequency separation on two‐tone auditory brainstem responses (A)

Carol Sammeth, Robert Burkard, and Kurt Hecox

J. Acoust. Soc. Am. Volume 80, Issue S1, pp. S47-S47 (1986); (1 page)

Online Publication Date: 13 Aug 2005

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Two‐tone complexes have been used as stimuli in auditory brainstem response (ABR) studies examining two‐tone suppression and the critical band (Stanny and Elfner, 1983; Zerlin, 1986). The relative starting phase of the tones in a two‐tone complex can have dramatic effects on the stimulus envelope. In light of the onset nature of the brainstem response and its integration of energy over only the first few cycles of a tone‐burst stimulus (Suzuki and Horiuchi, 1983), phase effects on the stimulus envelope may be a confounding factor in two‐tone studies. We recorded ABRs to single‐tone stimuli, and to two‐tone complexes with homophasic and antiphasic relative starting phase. Frequency separations were arithmetically centered around 4000 Hz, and ranged from 200 to 3200 Hz. Relative starting phase had a significant effect on wave V amplitude for narrow frequency separations where stimulus envelope effects are most pronounced, but had no significant effect on wave V latency. ABRs to single‐tone stimuli were summed and compared to the responses obtained with the two‐tone complexes. The amplitude of the summed single‐tone responses exceeded the amplitude of wave V of the two‐tone complexes at all frequency separations. We conclude that relative starting phase of the tones in two‐tone complexes can significantly influence wave V amplitude, especially for small frequency separations.
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Relationship of the auditory brainstem response to time/intensity tradeability (A)

Mark Stephenson and William Melnick

J. Acoust. Soc. Am. Volume 80, Issue S1, pp. S47-S47 (1986); (1 page)

Online Publication Date: 13 Aug 2005

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Dichotic clicks were presented at 70 dB nHL to a group of 12 otologically normal male subjects. The clicks to one ear were attenuated by either 6 or 12 dB. Subjects were instructed to delay the onset of the click delivered to the contralateral ear until a single image was perceived at the center of their head. These same stimuli were then employed to evoke auditory brainstem responses. When the interaural intensity difference (IID) was 6 dB, a mean interaural time difference (ITD) of 151 μs effectively recentered the image. An IID of 12 dB was similarly offset by an ITD of 594 μs. A comparison of ABR latencies for time and intensity demonstrated greater differences for wave I than for wave II or V. The difference at wave I was significant for three out of four comparisons while at wave V only one out of four comparisons was significant. Differences between ABR response latencies to time versus those to intensity were most apparent as interaural differences were increased.
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Central masking paradigms and alterations in the auditory brainstem response (A)

Radha Simhadri‐Sumithra and George M. Gerken

J. Acoust. Soc. Am. Volume 80, Issue S1, pp. S47-S47 (1986); (1 page)

Online Publication Date: 13 Aug 2005

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Contralateral masking is often recommended in auditory brainstem response (ABR) testing in order to reduce or eliminate the participation of the nontest ear. The present study evaluates the effects of contralateral sound on the ABR. Vertex‐mastoid recordings were made on a total of 30 young‐adult subjects with normal heating. Stimulus paradigms employed a 4‐kHz probe and a contralateral continuous tone or a contralateral forward masker. Both the continuous‐tone and forward‐masking experiments resulted in statistically significant amplitude changes in the probe‐evoked ABR. Waves III and VI, averaged across experiments, conditions, and subjects, showed a 28.7% increase in amplitude in the presence of a contralateral stimulus. In contrast, the amplitude of wave V, averaged across experiments, conditions, and subjects, was reduced by 11.2%. Latency measures for all waves often showed a slight, but statistically significant, increase. In regard to the enhancement of wave III by contralateral sound, we speculate that the descending auditory system is involved. The amplitude changes obtained for waves III, V, and VI contrast strongly with earlier results on ipsilateral masking.
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Effects of attention on auditorily evoked potentials (A)

Francis K. Kuk and Paul J. Abbas

J. Acoust. Soc. Am. Volume 80, Issue S1, pp. S47-S47 (1986); (1 page)

Online Publication Date: 13 Aug 2005

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Auditorily evoked responses to tone bursts (4‐ms duration with 1‐ms rise/fall) were recorded from the promontory as well as the ipsilateral mastoid of five human listeners while they were performing a visual duration (standard light flash of 50 ms) and an auditory frequency (center frequency at 2, 4, and 8 kHz; 250‐ms duration) discrimination task. Response evoking tone bursts were presented prior to and between the discrimination tone bursts. Visual and auditory stimuli were presented simultaneously. ABR and AP measurements were made during separate sessions. The method of constant stimuli was used for the discrimination tasks and the separation between stimuli was set for the value of the difference limen determined during a training session. Recordings obtained with acceptable discrimination performance were analyzed. No difference in amplitude, latency, or shape of the recordings was observed between the two discrimination tasks. The results suggest that the attention demand of the present task is not a central factor in the control of the auditory efferents.
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Maturation effects on binaural interaction in human auditory middle latency evoked potentials (A)

D. L. McPherson, C. Tures, and A. Starr

J. Acoust. Soc. Am. Volume 80, Issue S1, pp. S47-S48 (1986); (2 pages)

Online Publication Date: 13 Aug 2005

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An interaction of the binaural auditory pathway may be observed in human auditory evoked potentials by subtracting the evoked potential to binaural stimulation from the sum of the evoked potential to monaural stimulation. The present study deals with the maturation of the binaural interaction component (BIC) of the middle latency potentials in infants and the difference seen between infants and adults. Eight adults and ten term infants were used in this study. Auditory evoked potentials were obtained for: (1) left monaural stimulation; (2) fight monaural stimulation; and (3) binaural stimulation. Individual binaural interaction waveforms were derived as described above. A shift of the major component of the binaural interaction between the adult and infant was observed. The largest BIC occurs in the adult at the time of P30 and N40 with a 41% interaction at P30 and a 21% interaction at N40. The morphology of the infant middle latency potentials differs significantly from the adult form by the narrowness of an N13 component and the lack of a clearly defined P30. N40 does not occur in the infant. The major interaction in the infant occurs at the time of N20, showing an interaction of 45%. This difference probably reflects changes in the middle latency components between adults and infants, with the adult showing a predominant P30‐N40 component. [Work supported in part by the National Institutes of Health and the National Foundation March of Dimes.]
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The use of paired clicks to examine forward masking in auditory brainstem responses (A)

Lawrence Shotland and Kurt Hecox

J. Acoust. Soc. Am. Volume 80, Issue S1, pp. S48-S48 (1986); (1 page)

Online Publication Date: 13 Aug 2005

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Forward masking was assessed in ten normal and ten sensorineural hearing‐impaired subjects using a paired‐click paradigm. Auditory brainstem responses (ABR) were obtained using single and paired clicks. The single or click pairs were repeated at 4.9/s while the separator between clicks for click pairs was 5 ms. First or single clicks were presented at 60 dB nHL for the normal listeners and at levels sufficient to produce a 6.0‐ms wave V in the hearing‐impaired group. The second click was presented at the same intensity, 10 dB, less intense, and 20 dB less intense than the first click. A digital subtraction technique was utilized to visualize the response to the second click in the pair. Differences in response threshold and in the rate of latency of amplitude growth were observed between the hearing‐impaired and normal population. Control conditions suggested that these findings cannot be attributed solely to differences in the level of presentation between the two groups. The contribution of adaptation/forward masking to the results found in the hearing‐impaired data will be discussed.
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Auditory sensitivity via BAEP and electrocochleography: Method for improved low‐frequency region response (A)

Neil Shepard, Laura Brady, and Eugene Potesta

J. Acoust. Soc. Am. Volume 80, Issue S1, pp. S48-S48 (1986); (1 page)

Online Publication Date: 13 Aug 2005

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Difficulty in realizing a repeatable low‐frequency region response near threshold for click (low‐frequency) or tone‐burst stimuli is partially due to the reduction in synchronous discharge of auditory nerve fibers innervating areas of the cochlea most sensitive to low‐frequency input. This problem is exacerbated by the use of random or alternating phase onset to reduce electrical and physiological interference. A method shown to eliminate the time smearing effect of random or alternating phase onset for click stimuli using a fixed phase onset with broadband masking and a subtraction technique was applied to tone‐burst stimuli for BAEP and EcochG recordings. Preliminary results show the technique to be as applicable to BAEP recordings and tone‐burst stimuli as with EcochG and clicks, provided a sufficient level of broadband noise is presented. The success regarding low‐frequency response in both normal‐hearing and hearing‐impaired subjects will be presented.
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Clinical validation of special hearing‐impaired norms for BAEP interpretation (A)

Neil T. Shepard, Mary‐Jo Burtka, and Robert G. Turner

J. Acoust. Soc. Am. Volume 80, Issue S1, pp. S48-S48 (1986); (1 page)

Online Publication Date: 13 Aug 2005

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A model predicting the effects of high‐frequency hearing loss of cochlear origin on the BAEP [N. T. Shepard and J. C. Webster, J. Acoust. Soc. Am. Suppl. 1 74, S40 (1993)] was used to develop criteria based on degree and configuration of loss of sensitivity for interpreting clinical BAEP testing. Two and one‐half years of experience with these criteria were reviewed by a retrospective study of 389 patients tested during that period. Validation of the model was indicated by an 8% increase in specificity of the test with no change in sensitivity when use of the special criteria were compared to criteria based solely on normal‐hearing subjects in the same clinical population. Also discussed will be overall BAEP performance, an explanation of high false positive rate based on population mix, and improved criteria for test enhancement.
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Auditory middle latency and steady‐state responses in infants (A)

David R. Stapells, Jamie A. Costello, Donna Smith, Scott Makeig, and Robert Galambos

J. Acoust. Soc. Am. Volume 80, Issue S1, pp. S48-S48 (1986); (1 page)

Online Publication Date: 13 Aug 2005

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The effects of stimulus rate, intensity, and tonal frequency on the auditory middle latency and steady‐state responses (MLR/SSR) were investigated in 29 normal infants (1–36 months) and in eight normal adults. Adultlike MLRs (10/s) were recordable in only 5 infants, 14 demonstrated responses with “immature” morphology, and ten demonstrated no MLR components after Na. Compared to adults, infant SSRs were lower in amplitude and demonstrate different scalp distributions. Unlike the adult data, no consistent amplitude peak was seen across rate, and phase coherence increased up to highest rate tested (59/s). Infants required higher stimulus intensities to produce adultlike SSR phase coherence values: 83% of the recordings to 70‐dB nHL tones presented at 43.4/s showed significant values (p <0.01), decreasing to 35% at 40 dB nHL. These results are very different from those we previously reported for adults [Stapells, Makeig, and Galambos, J. Acoust. Soc. Am. Suppl. 1 77, S66 (1985)], and suggest that infant MLRs and SSRs undergo complex changes with maturation. [Work supported by DRF and NIH.]
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Intensity discrimination: Relation of auditory‐nerve activity to psychophysical performance (A)

Bertrand Delgutte

J. Acoust. Soc. Am. Volume 80, Issue S1, pp. S48-S48 (1986); (1 page)

Online Publication Date: 13 Aug 2005

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In order to test the notion that saturation of auditory‐nerve fibers limits psychophysical performance in intensity discrimination at high stimulus levels, intensity difference limens (DL) of single auditory‐nerve fibers in anesthetized cats were measured for tones at the CF, using stimulus paradigms and detectability measures similar to those of psychophysics. The physiological DL reaches a minimum in the range of stimulus levels where discharge rate increases rapidly. In a narrow range of levels around the minimum, single‐fiber DLs approach psychophysical DLs. An optimum‐processor model that combines intensity information from an array of 30 000 auditory‐nerve fibers with a realistic threshold distribution predicts intensity DLs that are well below psychophysical DLs over a 90‐dB range of levels. This result implies that psychophysical performance is not limited by saturation in auditory‐nerve fibers, but by central factors. Suboptimal processors that give more weight to intensity information from high‐threshold fibers than to information from low‐threshold fibers can closely predict psychophysical DLs for both tones and broadband noise over a wide range of stimulus levels. Moreover, such processing schemes, which are based on average discharge rates, provide a stable representation of the spectra of speech sounds with respect to variations in intensity. [Work supported by NIH.]
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Cochlear tuning characteristics infants and adults (A)

J. Y. Bargones and E. M. Burns

J. Acoust. Soc. Am. Volume 80, Issue S1, pp. S48-S49 (1986); (2 pages)

Online Publication Date: 13 Aug 2005

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Cochlear tuning characteristics were estimated by obtaining suppression tuning curves (STCs) for spontaneous otoacoustic emissions (SOAEs) in infant and adult subjects. STCs were derived using 8 to 12 suppressor frequencies per SOAE. Infants were tested at approximately 3 weeks, 2 months, and 3 months of age. Adults were tested three times over a period of 3 months. Quantitative analyses include Q‐10, Q‐20, slopes of the high‐ and low‐frequency segments of the tuning curve and tip frequency. Results indicate that cochlear tuning properties in infants approximate those found in adults; however, greater variability is observed for repeated measures of infants STCs. The results are discussed with respect to the development of frequency selectivity. [Work supported by NINCDS.]
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Frequency selectivity of the active cochlear filters inferred from otoacoustic emissions evoked by steady‐state tones (A)

Pierre L. Divenyi

J. Acoust. Soc. Am. Volume 80, Issue S1, pp. S49-S49 (1986); (1 page)

Online Publication Date: 13 Aug 2005

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Spontaneous otoacoustic emissions have been shown to represent an oscillatory process rather than amplification of a narrow‐band noise centered at the emission frequency: Instantaneous amplitudes of the emission have the bimodal distribution characteristic to oscillations (W. Bialek and H. P. Wit, Phys. Lett. 104A, 173–178). The present paper attempts to demonstrate that similar bimodal distributions may be observed when the response to a low‐level (<30 dB SPL) steady‐state tone is recorded near the tympanic membrane and the energy at the tone frequency is eliminated from the recording. At either side of the stimulus frequency, points at which the narrow‐band instantaneous amplitudes shift from a unimodal to a bimodal distribution may be mapped into bandwidths that are comparable to those deriving from physiological measurements of the tip of the tuning curve. [Work supported by the Veterans Administration.]
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Otoacoustic emissions and cochlear pathology (A)

J. L. Grizzle, P. L. Divenyi, and H. J. Simon

J. Acoust. Soc. Am. Volume 80, Issue S1, pp. S49-S49 (1986); (1 page)

Online Publication Date: 13 Aug 2005

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Otoacoustic emissions, evoked by clicks and brief tone bursts, were measured in normal‐hearing subjects and patients with sensorineural hearing loss. The emissions were recorded using an electret microphone assembly inserted in the meatus. The stimulus was delivered through a transducer attached to a 1.3‐mm plastic tube terminating at approximately 1 cm from the eardrum. Spectral analysis of the click‐emitted emissions showed discontinuities similar to those observed in spontaneous emission recordings. In addition, the comparison of emission and audiometric data in the impaired ears will be reported. [Supported by the Veterans Administration.]
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