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PubMed2002

Diagnostic implications of stimulus polarity effects on the auditory brainstem response.

The purpose of this study was to determine whether clicks presented in rarefaction or condensation modes produce more accurate diagnostic information. Subjects were 20 consecutive patients who were seen at the Mayo Clinic for unilateral acoustic neuromas. The nontumor ear served as a control to minimize intersubject variability in the latencies. A standard audiologic evaluation was followed by an auditory brainstem response (ABR) test for which the stimuli were rarefaction and condensation clicks. Responses were analyzed for the presence of waves I, III, and V; absolute latencies of waves I, III, and V; interpeak intervals I-III, III-V, and I-V; and interaural latency difference for wave V. The results indicated that measures from both polarities were similar in this set of patients and that neither click polarity provided diagnostic advantages over the other. Recommendations are to collect ABRs to both click polarities individually to obtain the full complement of waves on which to base the diagnostic impression.

Auditory Threshold↗
PubMed2003

[A study on the correlation between distortion product otoacoustic emissions and transient evoked otoacoustic emissions].

OBJECTIVE: To study the characteristic and correlation of distortion product otoacoustic emissions and transient evoked otoacoustic emissions. METHOD: Contrast Band SNR and Band response amplitude of TEOAE with 2f1-f2 amplitude and SNR of DPOAE were investigated in states before or after noise exposure with or without contralateral suppression(CS) in 20 (40 ears) normal otologic youth volunteer subjects. RESULT: Although evoked by different acoustic stimulus and showed various characteristics of patterns respectively, DPOAE and TEOAE had a good correlation between their measuring values at most adjacent frequencies thus formed certain value relation. CONCLUSION: TEOAE measurement is save time and superior in middle frequency range while DPOAE measurement is better frequency specific and superior in the higher frequency. Between their amplitude and SNR there were good correlations so significant linear regression parameters can be obtained. According to these mentioned above they could be selected and used, moreover, make up a deficiency each other in scientific research and clinical practice.

Adult↗
PubMed1992

Otoacoustic emissions, audiometric sensitivity loss, and speech understanding: a case study.

The clinical measurement of otoacoustic emissions can assist in differentiating between peripheral and central explanations for deficits in speech understanding. We present audiometric and distortion-product emission data in a case with sensorineural hearing loss and a deficit in speech understanding. The presence of evoked emissions argues against attributing the speech audiometric loss to cochlear defect.

Adult↗
PubMed1992

Auditory brainstem response to tone bursts in quiet, notch noise, highpass noise, and broadband noise.

This study investigated the effects of tone bursts (1000 Hz, 2000 Hz, and 4000 Hz) in quiet, notch noise, highpass noise, and broadband noise on the identifiability, latency, and amplitude of the auditory brainstem response (wave V). Normal listeners were presented with 40 dB and 80 dB nHL tone bursts having rise-plateau-fall times of 1 msec. Wave V was observed in all subjects at 40 dB and 80 dB nHL for the quiet and noise conditions. The latency findings suggest that responses elicited by the 80 dB nHL tone bursts in quiet were, in part, mediated by regions on the basilar membrane that did not correspond to the center frequency of the tone burst. To increase frequency-specificity, high-level tone bursts (e.g., 80 dB nHL) should be mixed with notch, highpass, or broadband noise. The use of noise conditions for low intensity levels (e.g., 40 dB nHL) does not appear necessary for isolating the response because both the notch and the highpass conditions yielded latencies similar to the quiet condition. Although similar wave V amplitudes were found at all frequencies, amplitudes were smaller for the broadband noise than for the quiet, notch, and highpass conditions. Thus, the latter conditions seem preferred.

Acoustic Stimulation↗
PubMed1992

A one-week test-retest reliability study of Brainstem Auditory Evoked Potentials.

Brainstem Auditory Evoked Potentials (BAEPs) are increasingly used in longitudinal evaluation of brainstem function. The reliability of the neurophysiological parameters and definition of the normal test-retest variability are required for such investigations. In the present study we submitted 20 healthy volunteers (10 males and 10 females; mean age 35.1 years, range 24-49) to BAEPs in two sessions separated by seven days. The reliability of the parameters was estimated by means of intraclass correlation coefficient (R). All BAEP parameters showed excellent R values (above 0.75). In addition, the confidence interval lower limits of all R coefficients had good to excellent values. Finally we computed the upper normal limits of the test-retest variability of each parameter, with alpha = 0.01, using the within-subjects mean square. The confirmed good reliability of the analyzed parameters enables us to employ BAEPs as useful monitoring instruments in longitudinal studies.

Adult↗
PubMed1992

[Evaluation of frequency selectivity from psychoacoustic tuning curves].

Psychoacoustic tuning curves (PTC) can be regarded as filter curves, whereas their forms represent hair cell activity. Different influences--for example, noise, toxins, pharmacological causes and age--can change the PTC as a consequence of changed frequency selectivity without indication of deterioration in the audiogram. The objective of this investigation was to determine the visually perceivable change in the PTC as a quantifiable result. In so doing, the PTC was transformed into a hyperbola characterized by a parameter Q5. An example demonstrates the temporal change of Q5 under the influence of pharmacological drugs.

Auditory Threshold↗
PubMed1992

Portable stimulus generator for obtaining high-frequency (8-14 kHz) auditory brainstem responses.

Currently, the most useful application of high-frequency (greater than or equal to 8 kHz) auditory evaluation is for serial monitoring of patients receiving potentially ototoxic agents. Many individuals, however, are unable to respond to behavioral auditory test techniques. An objective evaluation method such as the auditory brainstem response (ABR) is valuable with difficult-to-test individuals. Laboratory instrumentation has been demonstrated to evoke high-frequency-specific (8-14 kHz) ABRs with reliable intrasubject latencies over time. This instrumentation is limited, however, because it cannot be transported to the patient confined to a hospital room. A portable device has now been constructed to deliver high-frequency (8-14 kHz) tone-burst stimuli comparable to the lab system. This digital/analog high-frequency tone-burst stimulus generator weighs less than 5 pounds. It can be utilized with any ABR signal averager capable of generating a positive (condensing) click at approximately 4.8 volts. Case studies are presented to demonstrate the frequency-specific responses obtained with these high-frequency tone-burst stimuli.

Acoustic Stimulation↗
PubMed1992

Effects of sample size on the latency and amplitude of the auditory evoked response.

Experiment I investigated the effects of sample size (500 to 1500 stimulus repetitions) on the auditory brainstem response as a function of intensity (20 to 80 dB nHL) on a group of 10 normally hearing subjects. There was little change in identifiability, reliability, latencies, or amplitudes of Waves I, III, and V as the sample size increased from 500 or 750 to 1500 repetitions. These results suggest that 500 to 750 repetitions may be adequate when methods similar to those in the present study are used, and that the common clinical practice of employing approximately 1500 repetitions may unnecessarily prolong testing. Experiment II employed 12 hearing-impaired subjects who were tested at 10 to 40 dB SL using sample sizes from 250 to 4500 stimulus repetitions. Identifiability of all waves increased as sample size increased from 250 to 4500 repetitions. The largest changes in identifiability occurred when sample size increased from 250 to 1500 or 3000 repetitions, with little improvement as sample size increased from 3000 to 4500 repetitions. Examiners should monitor averaged responses and terminate testing as soon as a wave is identified. Contrary to expectation, there was no systematic change in the standard error of measurement for latency (approximately 0.07 ms) as sample size increased from 250 to 4500 repetitions. The standard error of measurement for amplitude decreased from approximately 100 nV with 500 repetitions to approximately 45 nV at 3000 repetitions. The improvement in reliability with increasing sample size may be explained by a decrease in the variability of background noise. A systematic decrease in amplitude also was observed as sample size increased. This observation may be explained by a reduction in the residual noise levels or because of time jitter or adaptation within the auditory pathways. Nonetheless, investigators who wish to use ABR amplitude measures for diagnosis may benefit from using a relatively large sample size.

Adult↗
PubMed1991

Effect of speech distinctions and age differences on auditory event-related potentials.

P3 event-related potentials were recorded from 37 subjects in two age groups (19-25 and 61-75 years) listening to tones, stop + vowel (CV) monosyllables, and isolated vowels. P3 latencies were found to be significantly longer for older subjects in all stimulus conditions. CV latencies were also significantly longer than simple tone latencies with the increase being approximately 1.30 msec/year. Latencies to the vowel stimuli were somewhat more variable but also tended to be greater than the tone latencies. P3 amplitudes were greater for the tone stimuli than for the speech stimuli, but no significant age effects were found.

Acoustic Stimulation↗
PubMed1991

Evoked potential assessment of auditory system integrity in infants.

One child in 750 is born with a handicapping hearing impairment. The methods available to screen and evaluate infants at risk (auditory brainstem responses, middle latency responses, and cortical auditory evoked potentials) are reviewed, explained, and illustrated with case histories.

Audiometry, Evoked Response↗
PubMed1990

[Computerized audiometry. Analysis and modeling of brain stem evoked auditory potentials].

The use of microcomputer for the Brain-Stem Response Audiometry was discussed. The obtained results using the computer system, the methodology and technique of hearing examination were presented. Special attention was called to modelling aspects of the components of the registered signal and the instability of generators in the neuronal structures of the acoustic pathway.

Audiometry, Evoked Response↗
PubMed1990

Update on frequency specificity of AEP measurements.

Auditory evoked potentials acquired with frequency-specific stimuli are useful in estimating hearing sensitivity in difficult-to-test patients. Stimulus characteristics, test methods, strengths, and limitations of the auditory brainstem response, SN10 response, middle latency response, and 40-Hz response are reviewed. Clinical strategies using frequency-specific stimuli are suggested for the evaluation of children and adults.

Acoustic Stimulation↗