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PubMed1995

Auditory time-intensity cues in the binaural interaction component of the auditory evoked potentials.

Binaural interaction in the brainstem and middle latency auditory evoked potentials to intensity (dI) and timing differences (dT) between the two ears was studied in 10 normal hearing young adults. A component reflecting binaural interaction in the brainstem potentials occurred at approximately 7 ms and was of largest amplitude when dI and dT were 0. The latency of the binaural interaction component gradually shifted and its amplitude decreased as dI or dT increased and binaural interaction became undetectable when dI = 16 dB or when dT > or = 1.6 ms. In the middle latency potentials binaural interaction components peaking at 20, 32, and 45 ms were defined that were also largest when dI and dT = 0. The latency of the interaction did not shift with changes in dT and dI whereas the amplitude gradually decreased but binaural interaction components were still evident even at the largest values of dI (30 dB) and dT (3 ms). Psychophysical judgments of binaural perceptions showed binaural fusion of the stimuli to persist with dT values up to 1.6 ms and that lateralization of the intracranial image was complete when either dT = 1.6 ms or when dI = 16 dB. The results suggest that the presence of a binaural interaction component of auditory brainstem potentials correlates with the fusion of binaural click stimuli and the amplitude of the binaural interaction component correlates inversely with the degree of lateralization of the intracranial image. Binaural interaction components of middle latency potentials persist and continue to change even after the binaural stimuli cannot be fused.

Acoustic Stimulation↗
PubMed2006

Effects of auditory pathway anatomy and deafness characteristics? (1): On electrically evoked auditory brainstem responses.

The purpose of this study was to distinguish the effects of different parameters on latencies of wave IIIe, wave Ve, and interpeak interval IIIe-Ve of electrical auditory brainstem responses (EABRs). EABRs were recorded from all the intra-cochlear electrodes in eight adult HiRes90K((R)) cochlear implant users. The relationship between latencies and stimulation sites in the cochlea was characterized to assess activity along the auditory pathway. Audiograms before implantation, psychophysics at first fitting and duration of deafness were used to describe the influence of deafness on latencies. A decreasing baso-apical latency gradient was found for waves IIIe and Ve, while the interpeak interval IIIe-Ve remained the same along the electrode array. Electrical stimulation enabling to stimulate various parts of the cochlea at the same time, this could indicate an anatomical way of compensating for the delay the acoustic wave takes to reach the cochlea apex in a non-implanted ear. However, psychophysical levels were also found to increase at the cochlear base showing that the latency gradient could result from an increasing gradient of neural degeneration toward the base. Correlations of EABR latencies with psychophysics, audiometric data and duration of deafness show that factors linked to deafness have indeed an influence on EABR latencies. The possible explanations for the latency shift observed, whether they are anatomical and/or pathological, are exposed.

Adolescent↗
PubMed2006

Auditory brainstem response findings and peripheral auditory sensitivity in adrenoleukodystrophy.

Measurements of the auditory brainstem response (ABR) were obtained in 96 individuals with X-linked adrenoleukodystrophy (X-ALD). The patients were divided into five diagnostic groups on the basis of neurologic diagnosis. The five groups were cerebral childhood and adolescent, pure adrenomyeloneuropathy (pure AMN), adrenomyeloneuropathy cerebral (AMN cerebral), Addison's only and symptomatic female heterozygotes. Results indicated the presence of marked ABR abnormalities for all groups most frequently involving Wave V, followed by Wave III and Wave I. Abnormalities of all interpeak latency intervals (i.e., I-III, III-V and I-V) were observed for all groups. ABR abnormalities were most frequently seen in the AMN-cerebral and pure AMN groups but were also common in the symptomatic female heterozygote group. The ABRs in the cerebral childhood and adolescent group were the least impaired of the five groups examined. Age was found to be a significant independent predictor of bilateral ABR abnormalities but VLCFA levels, MRI Loes score, and duration of symptoms were not found to be independent predictors of bilateral ABR abnormalities after adjusting for ALD phenotype. Patients with AMN were significantly more likely to have bilateral ABR abnormalities than the cerebral childhood and adolescent group after adjusting for age, duration of symptoms, EDSS score, VLCFA levels and MRI Loes scores. The prevalence of peripheral hearing loss was not found to exceed that present in age and sex matched normal control groups derived from the NHANES (1999-2000), indicating a lack of association between peripheral hearing loss and X-linked adrenoleukodystrophy. It was concluded that: (1) auditory sensitivity in X-ALD is not significantly impaired; (2) ABR abnormalities are a frequent finding and may be caused by abnormalities of fiber tracts in the region of the lateral lemniscus and inferior colliculus; and, (3) the abnormalities progress slowly and appear to be associated mainly with the AMN phenotype.

Acoustic Stimulation↗
PubMed2003

Estimation of hearing loss in children: comparison of auditory steady-state response, auditory brainstem response, and behavioral test methods.

The current pediatric test battery is limited in the severe-to-profound hearing loss range by the inability to obtain frequency-specific thresholds. Auditory steady-state response (ASSR) is an evoked potential test that can accurately measure auditory sensitivity beyond the limits of other test methods. The limited amount of clinical research, however, has delayed the acceptance of ASSR into the standard pediatric test battery. This study compared thresholds from 76 children using ASSR, ABR, and behavioral test methods. Resulting correlations were strong and supported the inclusion of ASSR into the standard pediatric test battery. ASSR testing provides audiometric information that is essential in the management of children with severe-to-profound hearing loss.

Audiometry, Pure-Tone↗
PubMed1992

Auditory distortion products measured with averaged auditory evoked potentials.

The purpose of this investigation was to describe the properties of averaged auditory evoked potential distortion products (AEP-DPs) in guinea pigs. This study provided a step toward developing a clinical index of nonlinear processing of auditory signals and supplied a baseline for studies evaluating the effect of cochlear damage on AEP-DPs. The amplitude of the AEP-DPs was evaluated as a function of f2/f1 ratio (1.12-1.52) and primary frequency (500 Hz-2000 Hz). The amplitude of the AEP cubic difference tone (AEP-CDT) increased with increasing f2/f1 ratio for the 500-Hz f1 primary and remained constant for the 800-Hz and 1700-Hz f1 primaries. The AEP-CDT generated by the 1100-Hz and 1400-Hz f1 primaries was maximum for the middle f2/f1 ratios (1.22, 1.32, and 1.42). The AEP-CDT could not be distinguished from the noise floor for the 2000-Hz f1 primary. The AEP difference tone (AEP-DT) was larger and more frequently identified than the AEP-CDT. The amplitude of the AEP-DT decreased with an increase in f2/f1 ratio. The decrease was more pronounced for low-frequency f1 primaries than for high-frequency f1 primaries.

Acoustic Stimulation↗
PubMed1990

Long latency auditory event-related potentials from children with auditory processing disorders.

The purpose of this study was to evaluate auditory event-related potentials, and related long latency components, in children with auditory processing disorders, and to compare these results with a normal group matched for age, intelligence, and gender. Results showed a significant latency increase for the N1, P2, and P3 components in the processing disordered group. Furthermore, the interpeak latency interval P2-P3 was significantly longer in the clinical group. In terms of amplitude measures, only P3 amplitude differed significantly between groups. These results suggest that the long latency potentials may be useful in the assessment of children with processing disorders.

Auditory Perception↗
PubMed2005

Threshold prediction using the auditory steady-state response and the tone burst auditory brain stem response: a within-subject comparison.

OBJECTIVE: The purpose of this study was to evaluate the accuracy with which auditory steady-state response (ASSR) and tone burst auditory brain stem response (ABR) thresholds predict behavioral thresholds, using a within-subjects design. Because the spectra of the stimuli used to evoke the ABR and the ASSR differ, it was hypothesized that the predictive accuracy also would differ, particularly in subjects with steeply sloping hearing losses. DESIGN: ASSR and ABR thresholds were recorded in a group of 14 adults with normal hearing, 10 adults with flat, sensorineural hearing losses, and 10 adults with steeply sloping, high-frequency, sensorineural hearing losses. Evoked-potential thresholds were recorded at 1, 1.5, and 2 kHz and were compared with behavioral, pure-tone thresholds. The predictive accuracy of two ABR protocols was evaluated: Blackman-gated tone bursts and linear-gated tone bursts presented in a background of notched noise. Two ASSR stimulation protocols also were evaluated: 100% amplitude-modulated (AM) sinusoids and 100% AM plus 25% frequency-modulated (FM) sinusoids. RESULTS: The results suggested there was no difference in the accuracy with which either ABR protocol predicted behavioral threshold, nor was there any difference in the predictive accuracy of the two ASSR protocols. On average, ABR thresholds were recorded 3 dB closer to behavioral threshold than ASSR thresholds. However, in the subjects with the most steeply sloping hearing losses, ABR thresholds were recorded as much as 25 dB below behavioral threshold, whereas ASSR thresholds were never recorded more than 5 dB below behavioral threshold, which may reflect more spread of excitation for the ABR than for the ASSR. In contrast, the ASSR overestimated behavioral threshold in two subjects with normal hearing, where the ABR provided a more accurate prediction of behavioral threshold. CONCLUSIONS: Both the ABR and the ASSR provided reasonably accurate predictions of behavioral threshold across the three subject groups. There was no evidence that the predictive accuracy of the ABR evoked using Blackman-gated tone bursts differed from the predictive accuracy observed when linear-gated tone bursts were presented in conjunction with notched noise. Similarly, there was no evidence that the predictive accuracy of the AM ASSR differed from the AM/FM ASSR. In general, ABR thresholds were recorded at levels closer to behavioral threshold than the ASSR. For certain individuals with steeply sloping hearing losses, the ASSR may be a more accurate predictor of behavioral thresholds; however, the ABR may be a more appropriate choice when predicting behavioral thresholds in a population where the incidence of normal hearing is expected to be high.

Acoustic Stimulation↗
PubMed1975

Auditory localization: role of auditory pathways in brain stem of the cat.

Cats were trained to localize sound in space. The animals' localization accuracy was determined before and after one of the following operations: 1) transection of the trapezoid body, 2) unilateral and 3) bilateral transection of the lateral lemniscus, 4) unilateral and 5) bilateral transection of the brachium of the inferior colliculus. The results after bilateral transections of the lateral lemniscus and the one deep bilateral transection of the brachium of the inferior colliculus indicate that some portion of the ascending auditory system must be intact above the medulla for an animal to be able to localize sound. A small loss in accuracy of localization was found after unilateral transection of the lateral lemniscus or brachium of the inferior colliculus. This loss, when compared with the much larger loss that monaural animals show, is an indication that binaural analysis, important for sound localization, occurs at the level of the medulla. Some transections of the trapezoid body resulted in a deficit in localization ability that appeared to be complete and permanent. The position of the lesions in the trapezoid body indicated that important encoding of the binaural cues to localization most likely occurs at the superior olivary complex, probably at the medial superior olive. But the trapezoid body or other commissures of the brain stem auditory system are probably also involved in transmission of information necessary for localization to higher centers.

Animals↗
PubMed1985

The central auditory conduction at term date and three months after birth. I. Composite group averages of brainstem (ABR), middle latency (MLR) and auditory cortical responses (ACR).

We are investigating the maturation of auditory evoked responses, as a potential diagnostic tool for the neurological examination of premature infants at the Intensive Care Unit for Prematures. In this communication we report the group composite averages of the BMC-ARs in a group of 25 mature and healthy newborns with a follow-up at 3 months of age. The ABRs showed a remarkable variability in wave I latency, with a relatively stable I-V central conduction time (CCT) of the brainstem. The ipsilateral II-V CCT does not differ appreciably from the contralateral II-V CCT. The MLR components NoPoNa and Nb, Nc, Nd are easy to identify in the group averages. Voltage asymmetry between stimulated versus non-stimulated side is slight but persistent in the newborn period as well as at 3 months of age. The group averaged ACRs, show an early complex within the latency reach of 100 ms and a slow W-shaped late complex, most distinct at 3 months. The results indicate that the protocol as applied constitutes a tool for the testing of conduction function of the auditory afference in newborns, even beyond the level of the brainstem. Group averaging offers a method to determine the intragroup stability of evoked potentials under investigation.

Acoustic Stimulation↗
PubMed2002

Comparison of auditory steady-state response and auditory brainstem response thresholds in children.

Recently, auditory steady-state responses (ASSRs) have been proposed as an alternative to the auditory brainstem response (ABR) for threshold estimation. The goal of this study was to investigate the degree to which ASSR thresholds correlate with ABR thresholds for a group of sedated children with a range of hearing losses. Thirty-two children from the University of Iowa Hospitals and Clinics ranging in age from 2 months to 3 years and presenting with a range of ABR thresholds participated. Strong correlations were found between the 2000-Hz ASSR thresholds and click ABR thresholds (r = .96), the average of the 2000- and 4000-Hz ASSR thresholds and click ABR thresholds (r = .97), and the 500-Hz ASSR and 500-Hz toneburst ABR thresholds (r = .86). Additionally, it was possible to measure ASSR thresholds for several children with hearing loss that was great enough to result in no ABR at the limits of the equipment. The results of this study indicate that the ASSR may provide a reasonable alternative to the ABR for estimating audiometric thresholds in very young children.

Auditory Perception↗
PubMed2002

Effect of prenatal auditory enrichment on developmental expression of synaptophysin and syntaxin 1 in chick brainstem auditory nuclei.

Neural activity plays an important role in shaping the developing brain. We have determined the consequence of increased auditory stimulation on the developmental profile of synaptic proteins, synaptophysin and syntaxin 1, in the chick brainstem auditory nuclei, nucleus magnocellularis and nucleus laminaris, by immunohistochemistry and western blotting techniques. The chick embryos were provided with patterned sounds of species-specific calls or musical notes of a sitar, a stringed instrument, in a graded manner from embryonic day 10 (E10) through hatching, for 15 min every hour. During normal synaptogenesis of nucleus magnocellularis and nucleus laminaris, synaptophysin immunoreactivity increased significantly from E8 to E20, in parallel with synapse formation, and reduced at hatching. The embryos receiving species-specific sound stimuli exhibited a similar pattern with higher levels of immunoreactivity, though the difference between the study groups was not statistically significant. The music stimulated embryos showed an earlier peak at E16, followed by a gradual decline until hatching. In all three groups studied, syntaxin immunoreactivity showed a surge at E12, followed by a decline at E16 and subsequent stabilization. The stimulated groups continually expressed higher amounts of syntaxin immunoreactivity. The results suggest that prenatal sound stimulation enhances the normal pattern of synaptic protein expression in these auditory nuclei.

Acoustic Stimulation↗
PubMed1996

An auditory cortical theory of primitive auditory grouping.

Auditory stream segregation is considered from the point of view of a theory of the central auditory system in which temporal information is spatially coded on three dimensions roughly corresponding to the level of the cochlea, the inferior colliculus and the auditory cortex, respectively. This theory is embodied in the form of a computational model which simulates peripheral and central processing including a cortical cross-channel correlation mechanism.

Journal Article↗
PubMedDate not supplied

Older persons' performance on auditory, visual, and auditory-visual presentations of the Edgerton and Danhauer Nonsense Syllable Test.

The speech sound discrimination abilities of 15 normal-hearing and 15 sensorineural hearing-impaired subjects between 55 and 65 years of age were assessed using videotaped presentations of the Nonsense Syllable Test (NST). Stimuli were presented in auditory (A), visual (V), and auditory-visual (AV) modes. All subjects received the stimuli in two trials for each presentation mode; hearing-impaired subjects were unaided for the first, and wore their own hearing aids for the second. Responses were transcribed phonemically and were scored by the phoneme method. Intra- and interjudge reliability was greater than 90%. Mean phoneme discrimination scores were plotted for each group across the three presentation modes. The results revealed that: both groups' performance improved from V to A to AV modes, but differences were apparent in the amount of increase across modes within each group; the NST differentiated between groups in the A and AV modes, but not in the V mode; the NST identified "poor" speechreaders in each group under both V and AV conditions; and consonant errors in the V mode formed seven homophenous categories based on place of articulation. The NST can be a useful screening test in auditory rehabilitation to distinguish those hearing-impaired persons who naturally take advantage of visual cues from those who do not.

Acoustic Stimulation↗
PubMed2005

Using auditory-visual speech to probe the basis of noise-impaired consonant-vowel perception in dyslexia and auditory neuropathy.

Both dyslexics and auditory neuropathy (AN) subjects show inferior consonant-vowel (CV) perception in noise, relative to controls. To better understand these impairments, natural acoustic speech stimuli that were masked in speech-shaped noise at various intensities were presented to dyslexic, AN, and control subjects either in isolation or accompanied by visual articulatory cues. AN subjects were expected to benefit from the pairing of visual articulatory cues and auditory CV stimuli, provided that their speech perception impairment reflects a relatively peripheral auditory disorder. Assuming that dyslexia reflects a general impairment of speech processing rather than a disorder of audition, dyslexics were not expected to similarly benefit from an introduction of visual articulatory cues. The results revealed an increased effect of noise masking on the perception of isolated acoustic stimuli by both dyslexic and AN subjects. More importantly, dyslexics showed less effective use of visual articulatory cues in identifying masked speech stimuli and lower visual baseline performance relative to AN subjects and controls. Last, a significant positive correlation was found between reading ability and the ameliorating effect of visual articulatory cues on speech perception in noise. These results suggest that some reading impairments may stem from a central deficit of speech processing.

Acoustic Stimulation↗
PubMed1998

Auditory-visual speech recognition by hearing-impaired subjects: consonant recognition, sentence recognition, and auditory-visual integration.

Factors leading to variability in auditory-visual (AV) speech recognition include the subject's ability to extract auditory (A) and visual (V) signal-related cues, the integration of A and V cues, and the use of phonological, syntactic, and semantic context. In this study, measures of A, V, and AV recognition of medial consonants in isolated nonsense syllables and of words in sentences were obtained in a group of 29 hearing-impaired subjects. The test materials were presented in a background of speech-shaped noise at 0-dB signal-to-noise ratio. Most subjects achieved substantial AV benefit for both sets of materials relative to A-alone recognition performance. However, there was considerable variability in AV speech recognition both in terms of the overall recognition score achieved and in the amount of audiovisual gain. To account for this variability, consonant confusions were analyzed in terms of phonetic features to determine the degree of redundancy between A and V sources of information. In addition, a measure of integration ability was derived for each subject using recently developed models of AV integration. The results indicated that (1) AV feature reception was determined primarily by visual place cues and auditory voicing + manner cues, (2) the ability to integrate A and V consonant cues varied significantly across subjects, with better integrators achieving more AV benefit, and (3) significant intra-modality correlations were found between consonant measures and sentence measures, with AV consonant scores accounting for approximately 54% of the variability observed for AV sentence recognition. Integration modeling results suggested that speechreading and AV integration training could be useful for some individuals, potentially providing as much as 26% improvement in AV consonant recognition.

Adult↗
PubMed1979

Trials with the auditory response cradle. 1--Neonatal responses to auditory stimuli.

The Auditory Response Cradle enables physiological response measures to be recorded from the neonate. Auditory responses are detected in the form of head rotation, startle, body activity and respiration changes. This paper reports the results of trials with 203 neonates using 250 and 1000 Hz pure tone and broad band noise stimuli. Response criteria are determined and spontaneous control 'responses' compared with those resulting from stimulus presentation. The response rate is correlated with the measured intra-meatal sound pressure level. Clear response thresholds are determined for all three stimuli. The sharpness of these motor thresholds is discussed and found to have significant implications for cost-effective neonatal auditory screening.

Head↗
PubMed1993

Development and use of auditory compact discs in auditory evaluation.

Two audio compact discs have been developed by the Department of Veterans Affairs for use in the assessment of auditory function. This report focuses on 1) the development of the first compact disc, which contains speech materials used in routine audiologic evaluations, and 2) an introduction to the second compact disc, which contains tonal and speech materials used in more elaborate auditory evaluations. The first disc (Speech Recognition and Identification Materials, Disc 1.1), which is in its second generation, contains spondaic words, several monosyllabic word tests (Rush Hughes PB-50s, CID W-22, Maryland CNCs, and Northwestern University [NU] No. 6), and the Synthetic Sentence Identification materials. The second disc (Tonal and Speech Materials for Auditory Perceptual Assessment), which was produced in conjunction with the Dartmouth-Hitchcock Medical Center, contains spondaic words in the MLD paradigm, dichotic materials (chords, nonsense syllables, digits, and sentences), segmented/alternated CNCs, high-pass and low-pass NU No. 6 materials, 45% and 65% compressed NU No. 6 materials, the same 45% and 65% compressed materials compounded with 0.3-s reverberation, frequency tone patterns, and duration tone patterns.

Compact Disks↗
PubMed2003

Neural correlates of an auditory afterimage in primary auditory cortex.

The Zwicker tone (ZT) is defined as an auditory negative afterimage, perceived after the presentation of an appropriate inducer. Typically, a notched noise (NN) with a notch width of 1/2 octave induces a ZT with a pitch falling in the frequency range of the notch. The aim of the present study was to find potential neural correlates of the ZT in the primary auditory cortex of ketamine-anesthetized cats. Responses of multiunits were recorded simultaneously with two 8-electrode arrays during 1 s and over 2 s after the presentation of a white noise (WN) and three NNs differing by the width of the notch, namely, 1/3 octave (NN1), 1/2 octave (NN2), and 2/3 octave (NN3). Both firing rate (FR) and peak cross-correlation coefficient (p) were evaluated for time windows of 500 ms. The cortical units were grouped according to whether their characteristic frequency (CF) was inside ("In" neurons) or outside ("Out" neurons) a 1-octave-wide frequency band centered on the notch center frequency. The ratios between the FRs and the rhos for each NN and the WN condition and for each group of neurons were then statistically evaluated. The ratios of FRs were significantly increased during and after the presentation of the NN for the "In" neurons. In contrast, the changes for the t" neurons were small and most often insignificant. The ratios of the p values differed significantly from 1 in the "In-In" and "In-Out" groups during stimulation as well as after it. We also found that the ps of "Out" neurons were dependent on the type of NN. Potentially, a combination of increased p and increased FR might be a neurophysiological correlate of the ZT.

Acoustic Stimulation↗