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Objective Ménière's disease affects the vestibular and audiologic systems; however, little is known about the relationship between audiometric and caloric function with increasing duration of disease. We employed a novel methodology to understand the longitudinal correlation between audiometric and caloric function in Ménière's patients. Study Design Case series with chart review. Setting Neuro-otologic tertiary care practice. Subjects and Methods Charts of 19 patients with unilateral Ménière's disease, as classified by the 1995 American Academy of Otolaryngology-Head and Neck Foundation criteria, were examined. We included patients with ≥2 videonystagmograms and audiograms. We excluded those with bilateral Ménière's, prior audiovestibular destruction, or symptoms suggesting concomitant vestibular pathology. Spearman's rank correlation of audiometric status (pure tone average [PTA], low PTA, and word recognition score [WRS]) and vestibular function (bithermal calorics) was performed. The study was Institutional Review Board approved (protocol 2015H0266). Results A total of 112 audiograms and 42 videonystagmographies were performed. There was a decline in affected ear hearing PTA and WRS with duration of disease ( r = 0.602, P < .001, and r = -0.573, P < .001, respectively). Similarly, there was a decline in vestibular function with increasing duration of disease ( r = 0.709, P < .001). There were moderate correlations between vestibular weakness and PTA, low PTA, and WRS ( r = 0.464, P = .002; r = 0.498, P = .001; and r = -0.518, P = .001, respectively). Conclusions There is a correlation between decline in objective hearing and horizontal semicircular canal function with time. As expected, this correlation is not 1:1, indicating differential involvement of both systems. Understanding this relationship may assist in counseling patients with regard to prognosis, natural history, and therapeutic interventions.

Objective: To perform hearing screenings on all newborns before hospital discharge, using auditory brainstem evoked responses with analysis of time, cost, and failure rates to evaluate and determine the screening practicality., Method: Over a 3-year period from January 1, 1993 to December 31, 1995, auditory brainstem evoked response screenings were performed on 15 749 infants born at Saint Barnabas Medical Center, Livingston, New Jersey, before their hospital discharge by certified/licensed audiologists. The auditory brainstem evoked response screenings were conducted using the Nicolet Compass Evoked Potential System., Results: A 3-year experience of testing 15 749 infants proved to be a cost-effective program with costs less than $30.00/baby. To date, 46 babies have been identified with bilateral sensorineural hearing loss and 6 babies with unilateral sensorineural hearing loss., Conclusions: The universal newborn hearing screening program at Saint Barnabas Medical Center has proved to be effective, beneficial, and necessary for an institution with more than 5000 births, annually. Early identification of hearing loss has resulted in infants receiving early intervention, and the screening program has provided education and follow-up services to both parents and physicians.

The interest of slow vertex response audiometry (cortical evoked response audiometry), mainly in the diagnosis of pseudohypacousis is reported. The procedure is of interest to forensic audiometry.

On the basis of recent advances in auditory physiology, new tests of cochlear function have been developed using measures of otoacoustic emissions. In the present report, the clinical potential for each of the four basic emission types is examined. In addition, the practical advantages of examining the ear with two specific types of evoked emissions, transiently evoked and distortion-product otoacoustic emissions, are reviewed in detail. Finally, the future role of tests of otoacoustic emissions in the diagnosis of hearing impairment is discussed. The current view is the evoked emissions hold promise as an essential part of the clinical examination of the auditory system.

Electrophysiological measurements of auditory function are especially indicated in children who are difficult to test by behavioral audiometry. This report is concerned with transtympanic electrocochleography (ECochG) findings in young children (0-3 years) who were examined over the last 6 years in order to extend behavioral audiometric data. On an average, 25% of the children tested with auditory brainstem responses (ABR) needed general anesthesia and were therefore also investigated with ECochG (n = 65). These ECochG children often showed developmental retardation, and behavioral audiometry was doubtful or not possible in 60% of them. ECochG thresholds were generally similar on both ears. Despite general agreement between thresholds obtained by ECochG and behavioral audiometry, differences were found in both directions, ECochG being better or worse than hearing in several children. Detection of severe threshold elevation and low frequency residual hearing remain major limitations of ECochG in the early diagnosis and rehabilitation of deafness in young children.

A population of very low birthweight infants consisting of 41 infants (24 female) less than 1000 g birthweight and 108 infants (63 female) 1000-1499 g birthweight received auditory brainstem response audiometry (ABR) before initial discharge from hospital and were subsequently monitored via behavioural audiometry and tympanometry as part of their pediatric medical team follow-up assessment at age 7 months. Results support the use of ABR but indicate that its diagnostic yield was enhanced by the use of multiple ABR parameters in combination with basic audiological techniques. The commonly used single-value ABR pass/fail criterion was not found to be clinically practical.

Auditory evoked brain stem response (ABR) was recorded in two groups of cats during artery ligation. Group A underwent bilateral ligation of the vertebral artery (V.A.) for 180 min after which bilateral ligation of the carotid artery (C.A.) was done. In group B animals, initially V.A. was bilaterally ligated and right C.A. was also ligated, then after the same period, left C.A. was additionally ligated. ABR changes were also observed under asphyxia induced by turning off the respirator. Ligation of V.A. bilaterally resulted in a trend toward prolongation of the ABR latencies (group A). Ligation of V.A. bilaterally and right C.A. resulted not only in a trend toward prolongation of the latencies, but also in an increase in the amplitude in wave III and V (group B). Asphyxia caused more rapid and remarkable changes in ABR than artery ligation. After the onset of asphyxia, temporary increase in the amplitude was observed before the waves deteriorated. ABR is affected by changes of the blood flow and asphixic condition. ABR changes possibly depend on the development of the collateral vessels, vasodilation effect, or increase in blood pressure after artery obstruction or sustained asphyxia.

The study of a simultaneous lobe-vertex and membrane-vertex recording in auditory brainstem response was performed in normal adults and in patients suffering from brainstem disorders. It was demonstrated that in normal subjects the detectability of waves I and V depends on the site of the recording electrodes and there is no statistical difference between the two recording methods in the latencies of the two waves. We reported 3 typical cases that illustrate the value of this recording method in the detection of the cochlear nerve or the brainstem disorders.

This is an investigation of the accuracy with which the 40-Hz evoked potential (EP) threshold can be used to predict low frequency behavioral audiometric thresholds. The EP thresholds for 500 and 1000 Hz tone bursts were compared with behavioral thresholds obtained from 40 hearing-impaired ears. Correlation coefficients (between EP and behavioral thresholds) of 0.79 and 0.87 were obtained for the 500 and 1000 Hz signals, respectively. Confidence intervals for EP estimates of behavioral thresholds were -10 to +30 dB for 500 Hz signals and -20 to +20 for 1000 Hz. Problems associated with the use of the EP for predicting behavioral thresholds are discussed.

The effect of the use of electric response audiometry (ERA) on the diagnosis and management of children has been investigated. A retrospective method was employed using the notes of the first 102 hearing assessments in 1978 where an ERA test was performed. The results show that the effect on diagnosis has been to improve the degree of certainty rather than to re-classify patients as deaf or normal. The effect on management has been to reduce by 24% the number of patients that require repeat assessment. These effects are more pronounced in the '0--1 age group' as opposed to the 'above 1 year' age group.

The shift in latency of wave V in ABR upon the reversal of stimulus phase was investigated in a normal-hearing reference material (65 ears) and in 20 ears of conductive hearing loss, 29 ears of steep high-frequency hearing loss and 17 ears of acoustic neurinoma or cerebellopontine angle tumor. In addition, reproducibility was studied in the reference material. The stimulus was a 2.0-kHz haversine wave at 75 or 35 dB nHL delivered at the rate of 20 Hz. 2000 responses were averaged for each stimulus phase. Electrodes were placed on the vertex and on ipsilateral mastoid. Stimulus wave form was determined in a 6-cc coupler and in a few cases with a miniature electrete microphone in the ear canal. In the reference material, a significant difference of the wave V latency between the condensation (C) and rarefaction (R) stimulus was observed. When taking the absolute difference, the mean value was 0.15 ms at 75 dB nHL. This time difference corresponds to a frequency of 3-4 kHz. In high frequency cochlear loss, the C-R difference increased in proportion to the downward shift in frequency of the high frequency slope of the audiogram. In conductive hearing loss, the C-R difference was similar to that of the reference material. In retrocochlear cases, the C-R difference was unpredictable, but was remarkably often small compared with the V latency. It was concluded that the difference in wave V latency between C and R clicks provides information about the excitation pattern in the inner ear but it is not reliable enough to give more than a rough estimate of the individual frequency of generation of ABR. The results are arguments against the use of the alternating stimulus phase as a routine procedure.

Interaural latency differences (ILDs) of wave V of the brainstem electric response (BSER) were studied (1) in 20 normal-hearing subjects at 90, 80, 60 and 40 dB HL click level, (2) in 22 patients with symmetrical cochlear hearing loss at 90 dB HL, corresponding to 45-80 dB SL, and (3) in 45 patients with asymetrical cochlear hearing loss with interaural recruitment, at 90 dB HL on one hand and at a click sensation level corresponding to 90 dB HL in the poorer ear (range 10-75 dB SL) on the other hand. In the normal hearing group the ILDs did not exceed 0.2 ms except in one case at 40 dB HL (0.3 ms). In the symmetrical cochlear loss group the ILD did not exceed 0.2 ms in any patient. In the asymmetrical cochlear loss group the ILD at 90 dB HL exceeded 0.2 ms in 12 cases, but only in four cases after correction for pure tone hearing loss at 4 kHz by 0.1 for each 10 dB above 50 dB HL; at equal sensation levels the ILDs were all zero or negative meaning that the wave V latency was shorter on stimulation of the poorer ear. Assuming ILD to be a valid discriminator between cochlear and retrocochlear lesions, the corrected ILD at equal click hearing levels (90 dB HL), with the critical value set at 0.2 ms, thus gave a 9% false-positive rate whereas the ILS at equal sensation levels, with the critical value set at zero, gave no false-positives. It still remains to be shown that the latter criterion will not increase the number of false-negative results in retrocochlear lesions.

Results of the comparison of action potential (AP) and summating potential (SP) parameters in trans- (TT) and extratympanic (ET) methods in 2 normal-hearing ears and 20 hearing-impaired ears with various etiologies and audiogram shapes are reported. In normal and impaired ears the TT/ET ratio of N1 amplitude was intensity dependent and was greater at higher intensities than at lower intensities. N1 latency was identical in both methods. The AP waveform was almost identical in both methods in ears except in a noise-induced hearing loss: N1/N2 ratio was greater in the TT method than in the ET method. In the TT method +SP at high frequency tone bursts and -SP at low frequency tone burst were recorded in Menière's disease and progressive sensorineural hearing loss, while in the ET method only -SP was recorded at a tone burst of each frequency. Origins of N1 and N2 and a clinical value of -SP and +SP are discussed.

We discuss our experience with evaluation of 167 children by auditory brainstem response audiometry in 1978. We summarize experience with referral sources, medication for sedation, and interpretation of test outcome. Medication for sedation was required for 136 children. Concommitant central nervous system involvement rendered auditory brainstem response ambiquous in some children; however, the technique still provide useful information about status of peripheral auditory sensitivity obtainable in no other way. Finally, agreement among auditory brainstem response, behavioral, and impedance audiometry predictions was usually quite good.

We evaluated predictive accuracy of the auditory brainstem response (ABR) to tone-pip and click signals in normal and hearing-impaired subjects. Prediction of hearing sensitivity based on threshold of the ABR to tone-pips of 500 and 2 000 Hz to clicks was compared to the behavioral results obtained by conventional pure-tone audiometry. Results showed that error in prediction was greatest for the 500 Hz tone-pip and least for the click. In addition, predictive error for the 500 Hz tone-pip varied with the contour of the pure-tone audiogram. In general, greatest predictive error was observed in subjects with steeply sloping audiograms.

The combination of suprathreshold tone-bursts with frequency of 0.5, 1 or 2 kHz and ipsilateral high-pass (HP) or notch noise masking has been studied in 52 adults referred for otoneurological examination on account of unilateral or asymmetric high-frequency hearing loss. Wave V latency changes are similar for both HP and notch noise masking and, in accordance with cochlear tonotopicity, are greater for the lower stimulus frequencies. Results are, however, not always conclusive with either technique, and response identification is problematical at 0.5 kHz. The less demanding HP masking technique is considered the method of choice since possible influence from the stapedius reflex is minimal and a better signal-noise ratio obtained.

Decreased EEG and EMG waves in sedated adults might produce more sensitive and better defined brainstem electric response. This was investigated by comparing the brainstem electric response to click stimulation in 10 adult volunteers before and during sedation with chloral hydrate. The results showed that there is no increase in sensitivity of the test in cooperative and relaxed adult subjects. The definition of wave I did not improve after sedation. It is therefore concluded that routine sedation is not advantageous in brainstem electric response audiometry in cooperative subjects.

Results of brainstem electric response audiometry (BERA) for intensive care nursery graduates and babies from the general nursery are described. At-risk babies received both screening and more detailed BERA before hospital discharge. The latter test was repeated after four months. From 2,597 risk assessments, 421 were at risk and 379 have been tested. The specificity of 40 dB click screening is good, but its sensitivity is only moderate. Follow-up BERA detected 25 cases of hearing loss, 12 having moderate loss in at least one ear. Discrepancies between predischarge and follow-up tests occurred, especially for mild losses. There was substantial resolution of hearing loss, but also some emergent mild loss. These changes support BERA at about four months as the determinant of habilitation, as opposed to predischarge testing. Differences between click and frequency-specific BERA were found, suggesting that click evaluations alone are insufficient.

Middle-component AERs (8-90 msec) to tone-pips from 10 normal-hearing adults were subjected to three objective methods of response identification. Threshold was then determined for each subject according to four different rules. The criterion score, which considers conjointly latency and amplitude values across the middle-component peaks, was developed as a single-value measure for response-identification and subsequent threshold-determination procedures. One of the response-identification methods was applied to 10 hearing-impaired subjects; the results of the threshold-determination procedures were encouraging. Further directions toward improving objective response analysis are discussed.

In order to demonstrate the possibility of deriving narrow-band responses, investigations using simultaneous pure-tone masking at frequencies of 1 and 0.5 kHz were carried out. Constant and reproducible derived responses were obtained at both masker frequencies within the following latency ranges: w6 (masker frequency 1 kHz) from 7.7 to 9.9 msec and w7 (masker frequency 0.5 kHz) from 9.2 to 11.2 msec at intensities of 70-20 dBSL. The agreement of our results with those obtained with the high-pass noise-masking technique permits us to ascribe our narrow-band responses (w6, w7) to the corresponding frequency regions around 1 and 0.5 kHz along the cochlear partition. This method is suitable for deriving frequency-specific responses without any sophistication.

A new computation complex and its operating algorithm are described that enable considerable time cut for studying the human acoustic system. The neurophysiological premises for accelerated examining the patients with various hearing pathology have been substantiated.

In two newborn infants who had experienced severe asphyxial insults, and who showed noticeable signs of brainstem dysfunction, all components of the auditory brainstem response except the eighth nerve potential became undetectable. Both babies survived, their brainstem responses returned, and one of them is judged to be developmentally normal at the age of 18 months. Clinical signs of brainstem dysfunction with complete cessation of conduction in the brainstem auditory pathway cannot be taken, therefore, as a sign of irreversible brainstem damage in the human newborn.

ABR (Auditory Brainstem Response) delivering the acoustic stimulus both through a headphone (PHN) and in free field (FF), have been recorded in 59 "normal" children divided into four age-related groups: (1) 22 children born at a gestational age ranging between the 36th and the 41st week; (2) 12 with ages ranging from 1 to 6 months; (3) 15 with ages ranging from 6 to 12 months; (4) 10 with ages ranging from 12 to 36 months. Peak latency values obtained with FF technique have been corrected by calculating the delay due to the distance between the loudspeaker and the tested ears (2.04 ms). When using this correction, no statistically significant differences were found between latency values of peaks JI and JV recorded using the two technique. While JI latency values of various groups do not differ significantly, groups 2--and especially group 1--JV latency values are statistically different from those of the 3rd and 4th group. This observation was confirmed by JV--JI interval values. JV wave in neonates (group 1), using PHN technique, is detectable at 60 dB p.e. SPL (82%) while in all other groups at 60 dB this wave is clearly detectable in all children (100%). Using FF technique, JV wave is still visible at 60 dB in 78% of the neonates (group 1) and in almost all children of the other groups. Considering ABR waveform, using PHN technique, in the first two groups only three waves are visible and the first one disappears at about 80 dB, while the typical 4--5 waves of normal adult tracings are detectable since 8--12 months of age. FF tracings instead show three peaks in all groups, the first (JI) being less evident when compared with the one obtained using PHN technique. JV amplitude values observed in FF are higher than those obtained delivering the stimulus through the headphone.

Ipsilateral and contralateral middle-component AERs (8-90 ms) were recorded from 20 normal neonates. AERs were elicited with either 500-Hz or 3000-Hz tone-pips presented monotically at 10, 30, and 50 dB HL. AERs also were obtained for silent control conditions. In general, latencies decreased and amplitudes increased with increasing stimulus level. Responses to 500-Hz tone-pips were larger than those for 3000 Hz. The results are similar to those obtained from adults. The neonates' middle-components, however, differ from those of adults in terms of the small contribution of the electroencephalic activity beyond 60 ms, and in the asymmetry between the ipsilateral and contralateral AERs.

Recently, in a ten-day-period, three patients whose hearing was within normal limits with good speech discrimination were found to have large cerebellopontine angle tumors. There were neurologic symptoms in only one patient. In these three cases, stapedius reflexes were absent with the affected ear stimulated. Brain stem evoked responses (BSER) were clearly abnormal in the three cases. Postoperative brain stem testing showed essentially no change in the nonoperated ear owing to brain stem manipulation. In two cases hearing was preserved. In one patient, the brain stem recordings returned to near-normal after surgery. In another, brain stem responses remained the same and the stapedius reflexes returned to normal. It appears that stapedius reflex testing and the BSER are highly useful tools that can be used to diagnose an acoustic neuroma before it grossly affects hearing.

Two experiments were conducted on normal hearing adults to assess the audiometric test potential of reflex modulation (RM) when administered according to the descending method of limits. RM describes the inhibitory effect of a tone upon a subsequently occurring eyeblink reflex. Although RM conducted according to the method of constant stimuli has already been shown to produce RM results which agree well with voluntary audiometry in normal and hearing-impaired adults and children, the present concern is with the potential clinical application of RM, and in this regard the descending method may offer certain distinct advantages. In study one, a 2-kHz tone was presented at several descending intensities, whereas in study two, four different frequencies (0.5, 1.2, and 4 kHz) were presented in concurrent fashion, but again, the intensity of the complete set was decreased in successive steps. Sensitivity in both cases was 10 to 15 dB SL. Implications for the clinical application of RM audiometry are discussed.

This study used a series of non-simultaneous masking stimuli set at subjects' pulsation threshold (PT) level to deduce frequency following potential (FFP) tuning curves for 500-Hz tone bursts at 80 and 100 dB SPL. PT and FFP tuning curves were determined in the presence and absence of continuous high-pass masking noise. Results from study demonstrated differences in FFP tuning curves, depending on the high-pass masking condition. High-frequency end of FFP tuning curve was diminished in the presence of high-pass masking noise. These findings suggested that higher frequency tone bursts were less effective in diminishing FFP amplitude when basal end of cochlea was masked. Findings suggest that cochlear initiation site of FFP extends beyond the apical turn of the cochlea at moderate and high intensity levels. A limited clinical use for FFP is suggested.

Brainstem electric response (BSER) and electrocochleography (ECochG) thresholds were measured in 55 ears of 46 'difficult-to-test' children. In most cases there was a reasonably close correlation between the two tests with BSER being less sensitive on the whole, but there was a small group, clinically indistinguishable from the majority, in whom an unacceptable discrepancy occurred. It was found that where the BSER threshold was equal to or less than 30 dB, the ECochG thresholds confirmed normal hearing, whereas if it was more than 30 dB further objective testing was essential to establish a definitive diagnosis of a hearing loss.

To assess the I-V interpeak latency (I-V IPL) as an index of neural development in a premature population, auditory brainstem response (ABR) performed on 145 ears of 89 neonatal intensive care unit (NICU) infants was analyzed. The obtained I-V IPLs were compared with conceptional age and risk factors such as neonatal asphyxia, respiratory distress, metabolic disorders, etc. Those infants who received phototherapy or aminoglycoside antibiotics had statistically significant prolongation of I-V IPL. Thus, measurement of I-V IPL might be a valuable monitor against risk factors.

Auditory MLR and ABR were recorded simultaneously in 9 children under general anaesthesia, after electrocochleography had demonstrated a normal hearing threshold. In contrast to the ABR components which in all cases appeared to be clearly recognizable, and with latencies within the normal range, MLR revealed gross abnormalities represented by instability of the components and abnormal latency of the detectable peaks. Since such variations in the MLR pattern may be thought of as a direct consequence of general anaesthesia, it seems likely that these potentials reflect a neural activity which, in children, is affected by CNS drugs.

The use of auditory nerve-brainstem responses in differential diagnosis of hearing loss is based on several properties of these responses including response latency. The auditory nerve response latency has been shown to be prolonged in conductive hearing loss. The latency of the brainstem responses is also often prolonged in retrocochlear hearing loss. However, the effect of sensorineural hearing losses on auditory nerve response latency is not clear. Several authors report that response latency is prolonged in sensorineural loss, whereas others claim that it is unchanged. To study this, auditory nerve-brainstem responses to 75 dB HL clicks were recorded in normal-hearing subjects and in those with various degrees of high-frequency sensorineural hearing loss. In the more extreme hearing losses, the auditory nerve response could not be seen in the response trace, so the latency of the earlobe positive wave from the region of the inferior colliculus was considered as mirroring auditory nerve response latency, since the time interval between these two waves has been shown to be constant. The average latency of the more severe hearing loss group (more than 40 dB hearing loss at 4kHz) was found to be only 0.35 ms longer than that of the normal-hearing group. This value is smaller than that seen in most conductive and retrocochlear hearing losses. This result warrants continued use of prolonged auditory nerve response latency (greater than 0.35 ms) as an indicator of conductive hearing loss. Possible explanations for smaller latency prolongation than expected of the auditory nerve response in sensorineural hearing loss are discussed based on the properties of single auditory nerve fibers.

The effect of contralateral white noise stimulation on ipsilaterally presented click evoked brain stem potentials was examined. Continuous contralateral white noise does not influence the brain stem response components but pulsed white noise simultaneously presented with the clicks produced a central masking effect which was observed as an amplitude reduction confined to Wave V. Our findings confirm those of Zwislocki (1971) that pulsed noise is a more effective central masker than continuous noise. A computer addition of the responses to pulsed white noise and clicks recorded independently revealed no reduction in Wave V amplitude but the response to the two stimuli presented simultaneously showed a specific reduction in Wave V amplitude. No change in the latency of Wave V was observed to suggest any 'cross-over' masking of the click stimulus. Patients with total unilateral deafness did not exhibit this phenomenon. The effect of a time delay of the masker to one ear in relation to the click presented to the other ear reduced the amplitude of Wave V less than when the two stimuli were presented simultaneously. The reduction in the amplitude, being specific to Wave V, suggests that the effect is central and that the particular locus for this aspect of central masking is at the level of the inferior colliculus.

The deaf child must receive sound amplification before he reaches the age of two years. At this age the hearing threshold is best measured objectively by electrocochleography (ECochG) and auditory brainstem response (ABR) audiometry. When used correctly, both methods allow an exact threshold estimation which is informative enough for adequate hearing aid prescription. Both methods have advantages and disadvantages when used in children. The advantages of ECochG are: (a) a more exact threshold estimation and (b) strictly monaural evaluation. The advantages of ABR are: (a) ease of performance; it is not invasive and does not require general anaesthesia and (b) allows for exploration of higher levels in the auditory pathway up to the midbrain. We believe that ECochG and ABR are compatible and complementary in the diagnosis of childhood deafness. ABR could be used in first instance, while ECochG could be reserved for doubtful cases and for those who cannot be adequately sedated. Extra-audiological factors such as the availability of anaesthetists and varying hospital facilities, play a further role in determining the choice of electric response technique.

The effect of click duration on the latency of waves I, III, and V was investigated by testing 20 normal-hearing subjects at 60 dB HL using electric pulses of 25, 50, 100, 200, and 400 microseconds. Alternating condensation and rarefaction clicks were used. The results revealed similar and nonsignificant latency differences for the 25-, 50-, and 100-microseconds pulses. However, the 100 microseconds duration is preferred to the 25-microseconds pulse because the latter reduced the maximum measurable hearing loss by about 13 dB. The results also showed that latencies increased approximately 0.10 ms as duration increased from 100 to 200 microseconds and by 0.20 ms when duration increased from 100 to 400 microseconds. Although such differences by themselves are small, they can combine with other stimulus or recording variables to be clinically significant. Therefore, it is important to control click duration when normative data are generated. A second experiment was conducted to assess the interaction of polarity (condensation, rarefaction, and alternating) and pulse duration (100 and 400 microseconds) on the wave V latency. These data revealed no latency differences among polarities at either duration.