Comparisons of Auditory Steady State Response and Behavioral Air Conduction and Bone Conduction Thresholds for Infants and Adults With Normal Hearing

Auditory steady state response (ASSR) testing provides a means to objectively estimate hearing levels in newborns and adults for whom behavioral tests prove difficult. When testing these patient groups, it is preferable that clear responses to both air and bone conduction stimuli are obtained in a short amount of time. Much of the literature addressing ASSRs, such as investigations of stimulus and recording parameters, have focused on air conduction ASSRs. The aim of this investigation was to study the amplitudes, latencies, and test times of bone conduction ASSRs elicited using amplitude- (AM), frequency- (FM), and mixed-modulated (MM) stimuli and provide suggestions for optimum recording parameters. Bone and air conduction multiple ASSRs were recorded from two groups of 20 normal-hearing adults using the Multiple Auditory Steady State Response research system. AM, FM, and MM sinusoidal tones were used (0.5-, 1-, 2-, and 4-kHz carrier frequencies), which were modulated between 78 and 92 Hz. AM depth was 100% and FM depth was 20%. ASSR amplitudes and latencies (calculated using the "preceding cycles" technique) were analyzed for MM phase settings across the cycle from 0° at 45° intervals and compared with AM responses. Optimum phase settings for bone and air conduction ASSRs were calculated using a sinusoidal model based on the amplitude data. Similar effects of stimulus type and carrier frequency were observed for bone and air conduction ASSRs. AM responses were larger in amplitude compared with FM responses. MM (at all phase settings tested) and AM response latencies increased with decreasing carrier frequency. MM phase setting had a significant (p < 0.01) sinusoidal effect on ASSR amplitudes, compared with AM responses, at 1, 2, and 4 kHz but not 0.5 kHz for air conduction and 1 and 2 kHz but not 0.5 and 4 kHz for bone conduction. Using a sinusoidal function to model this effect, MM phase settings (±95% confidence intervals) of 318° (295 to 350°) and 295° (290 to 310°) are predicted to evoke the largest responses for bone conduction ASSRs at 1 and 2 kHz, respectively. Phase settings of 293° (285 to 310°), 300° (280 to 310°), and 280° (255 to 330°) are predicted for air conduction ASSRs at 1, 2, and 4 kHz, respectively. MM phase setting had little effect on estimated latency. Test times were significantly (p < 0.01) affected by phase setting with both increases and decreases being observed. Test times for ASSRs at 1, 2, and 4 kHz could be significantly reduced if the estimated optimum phase settings are used. Different stimuli can significantly affect the amplitudes of bone conduction ASSRs. These effects are similar to those observed for air conduction ASSRs. MM stimuli with specific phase settings evoke larger bone conduction ASSRs compared with AM and FM stimuli alone, and calculations show that the time taken to obtain these responses is reduced. Implementation of the suggested optimum settings will promote efficient collection of bone conduction, and indeed air conduction, ASSR data.

Auditory steady-state responses to bone conduction stimuli in children with hearing loss

Two-channel recordings of infants' air- and bone-conduction auditory brainstem responses to brief tones show ipsilateral and contralateral (to the stimulated ear) asymmetries which may be used to isolate which cochlea is the primary contributor to the response. The objective of this study was to determine whether similar ipsilateral/contralateral asymmetries are also present in the air- and bone-conduction "brainstem" (77 to 101 Hz) auditory steady-state responses (ASSRs) of infants. Two-channel ASSRs were recorded in infants (2 to 11 mo) and adults (18 to 40 yr) with normal hearing. Multiple stimuli (carrier frequencies: 500 to 4000 Hz; amplitude/frequency modulated) were presented using a B-71 oscillator on the temporal bone or an ER3-A insert earphone. Bone-conduction ASSR amplitudes, phase delays, and thresholds were obtained for the electroencephalographic (EEG) channels ipsilateral and contralateral to the oscillator temporal-bone placement. Bone-conduction ASSRs were also obtained to the stimulus presented to the opposite temporal bone (at 40 dB HL only). Air-conduction ASSR amplitudes and phase delays were obtained at 60 dB HL in each ear for the EEG channels ipsilateral and contralateral to the transducer. Infants showed more ipsilateral/contralateral asymmetries in both air- and bone-conduction ASSRs compared with adults. Mean bone-conduction ASSR thresholds in infants were 13 to 15 dB higher (i.e., poorer) in the contralateral EEG channel compared with the ipsilateral EEG channel for 500 to 4000 Hz. In adults, there were no large differences (i.e., within 1 dB) between ipsilateral and contralateral ASSR thresholds. Based on ipsilateral/ contralateral threshold differences in infants, interaural attenuation for bone-conducted stimuli was estimated to be at least 10 to 30 dB for most infants. In contrast, most adults showed little interaural attenuation for bone-conducted stimuli. ASSR amplitudes are larger and phase delays are shorter in the ipsilateral EEG channel. For infants, the difference in air-conduction ASSR amplitude between EEG channels was twice that observed for adults. Infants also had greater ASSR amplitude differences between EEG channels for bone-conduction stimuli compared with adults, but the difference was less than that seen for air-conduction stimuli. For air-conduction stimuli, infants had significantly longer phase delays in the contralateral EEG channel compared with the ipsilateral EEG channel. Adults showed no significant differences in air-conduction ASSR phase delay between EEG channels. For bone-conduction stimuli, both infants and adults had significantly longer phase delays in the contralateral EEG channel compared with the ipsilateral EEG channel; the differences in ASSR phase delays between EEG channels were much smaller in infants compared with adults and fewer adults had absent responses in the contralateral EEG channels compared with infants (12% versus 34%). When the transducers were switched to the opposite ear/mastoid, the infant and adult ipsilateral/contralateral asymmetries also switched. Ipsilateral/contralateral asymmetries in air- and bone-conduction ASSRs are clearly present more often and are larger in infants compared with adults. Our findings also suggest that most infants have at least 10 to 30 dB of interaural attenuation to bone-conducted stimuli. These asymmetries in the bone-conduction ASSR have potential as a clinical tool for isolating the cochlea that is contributing to the response in infants.

To obtain ear-specific bone conduction thresholds, masking of the nontest ear is often required. Bone conduction masking has not been formally investigated for infants assessed physiologically. The objective of this study was to determine effective masking levels (EMLs) for auditory steady state responses (ASSRs) elicited by bone-conducted stimuli in a group of normal-hearing infants and adults. Participants were 15 infants younger than 6 mo and 15 adults, all with normal hearing. EML was defined as the lowest level of a binaural air-conducted masker that resulted in absent bone conduction ASSRs. Stimuli were single bone-conducted tones that were 100% amplitude modulated and 25% frequency modulated at 85 and 101 for 1000 and 4000 Hz, respectively. The stimuli were calibrated in dB HL (ANSI S3.6-1996) and expressed in dB HL or dB SL (dB relative to mean bone conduction ASSR thresholds reported in a previous study). The maskers were 1 and 4 kHz narrowband noise generated by a clinical audiometer. Unmasked and masked ASSRs were obtained for each participant. Real ear-to-coupler differences (RECDs) were also obtained for each participant and were used to convert masker dB SPL measured in the coupler to dB SPL in the individual ear canal. Infant EMLs for ASSRs elicited to bone-conducted stimuli in dB HL were 6 to 7 dB higher and 8 to 10 dB lower for 1000 and 4000 Hz, respectively, compared with adults. When masker was adjusted for RECDs, infant EMLs were 12 dB higher at 1000 Hz and similar at 4000 Hz compared with adults. When the stimulus levels were corrected for the mean differences in ASSR bone conduction thresholds between infants and adults and the masker levels adjusted for RECDs, infants had lower EMLs at 1000 Hz and equal EMLs at 4000 Hz, in comparison to adults. Frequency- and level-dependent effects on ASSR amplitude due to masking were found and differed between infants and adults. Our findings indicate that there are frequency- and level-dependent infant-adult differences in EMLs for bone conduction ASSRs and confirm that a 1000 Hz stimulus is 12 dB more effective for infants compared with adults. The following infant preliminary masking levels for bone conduction stimuli are recommended: (i) 1000 Hz: 48 and 58 dB SPL at 15 and 25 dB HL, respectively, and (ii) 4000 Hz: 40 and 45 dB SPL at 25 and 35 dB HL, respectively.

The objective of this study was to compare bone-conduction (BC) auditory steady-state responses (ASSR) for infants and adults with normal hearing to investigate the time course of maturation of BC hearing sensitivity. Bone-conduction multiple ASSRs were recorded in 0–11-month-old (n=35), and 12–24-month-old infants (n=13), and adults (n=18). Low-frequency BC ASSR thresholds increased with age, whereas, high-frequency ASSR thresholds were unaffected by age except for a slight improvement at 2000Hz. Compared to adults, BC ASSR amplitudes for young infants were larger for low frequencies, whereas, their amplitudes were smaller or similar for high frequencies. Compared to adults, young infants are much more sensitive to low-frequency BC stimuli, and probably more sensitive to high-frequency BC stimuli; these differences between infants and adults persist until at least two years of age. Different ‘normal levels’ for infants of different ages must be used and are proposed in this study.

Auditory steady state responses (ASSRs) to multiple air conduction (AC) stimuli modulated at ∼80 Hz have been shown to provide reasonable estimates of the behavioral audiogram. To distinguish the type of hearing loss (i.e., conductive, sensorineural, or mixed), bone conduction (BC) results are necessary. There are few BC-ASSR data, especially for individuals with hearing loss. The present studies aimed to (1) determine multiple ASSR thresholds to BC stimuli in adults with normal hearing, masker-simulated hearing loss, and sensorineural hearing loss (SNHL) and (2) determine how well BC-ASSR distinguishes normal versus elevated thresholds to BC stimuli in adults with normal hearing or SNHL. Multiple ASSR and behavioral thresholds for BC stimuli were determined in two studies. Study A assessed 16 normal-hearing adults with relatively flat threshold elevations produced by 50, 60, and 70 dB SPL AC masking noise, as well as no masking. Study B assessed 10 adults with normal hearing and 40 adults with SNHL. In both studies, the multiple (500 to 4000 Hz) ASSR stimuli were modulated between 77 and 101 Hz and varied in intensity from 0 to 50 dB HL in 10-dB steps. Stimuli were presented using a B71 bone oscillator held on the temporal bone by an elastic band while participants relaxed or slept. Study A: Correlations (r) between behavioral and ASSR thresholds for all conditions combined were 0.77, 0.87, 0.90, and 0.87 for 500, 1000, 2000, and 4000 Hz, respectively. ASSR minus behavioral threshold difference scores for all frequencies combined for the no-masker, 50, 60, and 70 dB SPL masker conditions were 14.3 ± 9.2, 12.1 ± 10.4, 12.7 ± 7.7, and 11.4 ± 8.1 dB, respectively. Study B: The difference scores for 500, 1000, 2000, and 4000 Hz were, on average, 15.7 ± 12.3, 10.3 ± 10.7, 9.7 ± 10.3, and 5.7 ± 7.9 dB, respectively, with correlations of 0.73, 0.84, 0.87, and 0.94 for the normal-hearing and SNHL groups combined. The ASSR minus behavioral difference scores were significantly larger for 500 Hz and significantly smaller for 4000 Hz compared with 1000 and 2000 Hz. Across all frequencies, the BC-ASSR correctly classified 89% of thresholds as "normal" or "elevated" (92% correct for 1000, 2000, and 4000 Hz). The threshold difference scores and correlations in individuals with SNHL are similar to those in normal listeners with simulated SNHL. These difference scores are also similar to those shown by previous studies for the AC-ASSR in individuals with SNHL, at least for 1000 to 4000 Hz. The BC-ASSR provides a reasonably good estimate of BC behavioral threshold in adults, especially between 1000 and 4000 Hz. Further research is required in infants with hearing loss.

The number of commercially available evoked potential systems implementing multiple-frequency auditory steady-state response (ASSR) techniques has increased over the last several years. The majority of data in the multiple-frequency ASSR literature have been obtained using time-domain averaging and Fast Fourier Transform (FFT) techniques with F-test statistical analysis. Another commercially available analysis method has been introduced using an adaptive filtering algorithm called the Fourier Linear Combiner (FLC). No previous investigation has evaluated the performance of the FLC method, nor compared the two techniques. In addition, there is a need for evaluation of clinical protocols for ASSR testing using these available commercial systems that balance time efficiency and accuracy in estimating threshold. (1) To determine whether ASSR thresholds, the relationship between ASSR and behavioral thresholds, and clinical test time are affected by the ASSR analysis method when comparing two commercially available systems for multiple-frequency ASSR. (2) To investigate the use of clinical ASSR test protocols of varying recording length, and the effect on accuracy and time efficiency, using these two commercially available analysis methods. RESEARCH DESIGN AND STUDY SAMPLE: ASSR threshold searches were completed on a group of 20 normal-hearing and 20 hearing-impaired adult participants using two different analysis methods, FFT and FLC, under separate, independent, tests as well under simultaneous recording conditions. Three experiments were completed: (1) independent assessment of ASSR thresholds using the FFT and FLC methods separately, (2) simultaneous recording of ASSR for both the FFT and FLC method, and (3) an automated threshold search protocol using the FLC method. Variables analyzed for Experiments 1 and 3 included ASSR thresholds, the difference between ASSR and behavioral threshold, and total test time. For Experiment 2, the number of detected ASSRs per method, the agreement between methods, and the time per detected ASSR were evaluated. ASSR thresholds and the relationship between ASSR and behavioral thresholds were found to be in line with those reported in the literature for multiple-frequency ASSR for both the FLC and FFT methods. ASSR thresholds were found to be significantly higher for the FLC method for the low frequencies, but not for the high frequencies, when tested independently. Correlations between ASSR and behavioral thresholds, however, were found to be the same across methods. Overall, it did not appear that either analysis method held an advantage in terms of accuracy or overall test time in independent comparisons using the protocol implemented in the current study. The time benefits of an automated protocol were significant, although with compromised test accuracy. The results of this study suggest critical clinical decision making is a necessary part of the ASSR protocol in order to decrease false positive and false negative responses and to increase overall efficiency.

Background: Narrowband CE Chirps (NB CE-chirps) were used to provide the characteristics of compensation for the cochlear traveling wave delay and frequency specificity.Aim: The aim was to compare the objective frequency-specific hearing thresholds estimation by the use of NB CE-chirps ASSR and behavioural thresholds in normal hearing subjects and patients with the conductive hearing loss.Subjects and methods: The cases group comprised 35 ears of 25 patients with the conductive hearing loss with varying degree from mild to severe in severity and their age ranging from 15 to 60 years. They were compared with 20 ears of 10 adult control subjects with normal hearing thresholds, whose age ranged from 19 to 42 years. All cases and controls were subjected to pure-tone audiometry (PTA), tympanometry and auditory steady-state response (ASSR), using 4 NB CE-chirp for air conduction (AC) and bone conduction (BC) threshold estimation.Results: AC-ASSR estimated thresholds were statistically significantly higher than AC PTA thresholds at 500, 1000, 2000 and 4000 Hz in both the cases and the control groups. BC ASSR estimated thresholds were statistically significantly lower than BC PTA thresholds only at 500 Hz in the cases and statistically significantly higher than BC PTA thresholds only at 2000 Hz in the controls. There was a statistically significant positive correlation between AC-ASSR and AC PTA, and between ABG-ASSR and ABG PTA in the cases group.Conclusions: Auditory steady-state responses with NB CE-chirps is suitable tool for objective frequency-specific hearing threshold detection, that can be used for estimation of behavioural bone conduction thresholds in adults with conductive hearing loss, with more accuracy in the mid frequencies, and can estimate behavioural air conduction thresholds and air-bone gap more accurately in the higher frequencies 2000, 4000 Hz more than at 500 and 1000 Hz.

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. 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. 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. 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.

Prospective data analysis. The intraoperative measurement of auditory brainstem responses (ABR) enables the assessment of the coupling efficiency in active middle ear implant surgeries. Furthermore, auditory steady-state response (ASSR) measurements can offer additional frequency-specific evaluations. This study aims to examine the efficacy of intraoperative ASSR and ABR measurements and optimize implant placement during surgery. Tertiary referral center with an extensive active middle ear implant program. Main outcome measures: Intraoperative ABR and ASSR measurements were conducted using a standard ABR system and the AcoustiAP adapter. After the surgical procedure, vibrogram thresholds were measured. The statistical analysis determined correlations between intraoperative ASSR and ABR thresholds, preoperative bone conduction, and postoperative vibrogram thresholds. All patients underwent successful intraoperative recording of ABR and ASSR measurements. The ASSR thresholds exhibited a high correlation with bone conduction thresholds at 1000 Hz, 2000 Hz, and 4000 Hz. Furthermore, ASSR thresholds demonstrated robust correlations with postoperative vibrogram thresholds. Intraoperative ASSR measurements can provide valuable real-time feedback for ensuring optimal placement during implantation due to their good correlation with bone conduction. The high correlation between intraoperative ASSR and postoperative vibrogram thresholds indicates that ASSR can also assess postoperative hearing outcomes. Further development and implementation of these measurements in the clinical routine might improve surgical outcomes by enabling more precise frequency-specific assessments, improving both coupling efficiency and postoperative hearing results.

Background: Auditory steady-state responses (ASSRs) are periodic scalp potentials that arise in response to auditory stimuli. Narrow-band (NB) CE-Chirps stimuli have been developed to combine the advantages of compensation for the cochlear traveling wave delay and frequency specificity.Objectives: To measure the hearing threshold objectively using ASSR in adults with normal behavioural hearing thresholds and adult patients with different degrees of sensorineural hearing loss (SNHL) and its comparison to the behavioural thresholds.Methods: In the present study, 35 subjects (70 ears) were enrolled. Ears were grouped according to the level of hearing obtained by pure tone audiometry (PTA) into 7 equal groups. NB-CE-Chirp ASSR was done for all groups by means of auditory-evoked potential device.Results: The estimated ASSR audiograms configuration matched the behavioural curves. ASSR was equally accurate at all frequencies tested except for 1 kHz in the normal-hearing group who showed less accuracy compared to 500 and 4000 Hz in air conduction (AC) and in bone conduction (BC). Although the AC estimation was not equal among the different degrees of hearing compared to the BC estimation, the AC PTA-ASSR thresholds difference range was small. BC PTA-ASSR threshold difference was statistically significantly less than AC at all tested degrees of hearing loss, in most of the frequencies; which reflects that the ASSR was more accurate in estimating BC than the AC thresholds. There was a negative correlation regarding behavioural BC PTA thresholds with PTA-ASSR threshold difference and PTA-estimated audiograms threshold difference at all tested frequencies.Conclusion: ASSR using either AC or BC NB-CE-Chirp is a reliable objective method in estimating the behavioural threshold in normal hearers and patients with various degrees of SNHL, so it can be used in difficult-to-test cases where accurate behavioural thresholds could not be obtained.

The aim of this study was to investigate the maturational time course of the occlusion effect in infants with normal hearing. The objectives were (i) to investigate the occlusion effect in a larger group of young infants, (ii) to determine whether the occlusion effect is seen in bone conduction auditory steady state responses (ASSRs) for older infants, and (iii) to investigate the mechanisms that underlie bone conduction hearing in unoccluded and occluded ears in infants by measuring sound pressure in the ear canal. Experiments 1A and 1B: The SPL in the ear canal to 500, 1000, and 2000 Hz bone-conducted pure tones were compared in 22 young infants (0-7 mo), 10 older infants (10-22 mo), and 34 adults, all with normal hearing, for unoccluded and occluded ears. Experiment 2: Bone conduction behavioral thresholds in 17 adults were compared for unoccluded and occluded ears at 500, 1000, 2000, and 4000 Hz. Experiment 3: Bone conduction ASSR thresholds and amplitudes were compared in 22 young infants, 10 older infants, and 20 adults for an unoccluded and occluded test ear. Stimuli were bone-conducted amplitude/frequency-modulated tones presented simultaneously at 500, 1000, 2000, and 4000 Hz. There were significant increases in sound pressure in the ear canal for stimuli presented at 40 dB HL when ears were occluded at 500 and 1000 Hz for all age groups. Infants showed the largest increases in SPL at 500 and 1000 Hz (5-8 dB > adults). Young infants showed no significant decreases in ASSR thresholds (2-6 dB) and amplitudes (0-10 nV) across frequency with occlusion; however, a significant number of infants had an occlusion effect at 500 Hz. Older infants showed a nonsignificant decrease in ASSR thresholds with occlusion (8 dB), a significant increase in ASSR amplitudes at 1000 Hz (6-21 nV), and a significant number of infants with an occlusion effect at 1000 Hz. Adult behavioral thresholds decreased significantly when ears were occluded at 500 and 1000 Hz; for ASSRs, thresholds also decreased (6-7 dB) and amplitudes increased (3-11 nV) at both 500 and 1000 Hz, but the mean trends and statistical findings were not in agreement in all cases. A significant number of adult subjects had an occlusion effect at 500 and 1000 Hz for both behavioral and ASSR thresholds. Our findings suggest that the occlusion effect for ASSR thresholds in young infants is small but emerging at 500 Hz but negligible at 1000 Hz and that the occlusion effect in older infants is emerging at both 500 and 1000 Hz. The clinical implications of these findings are that it is appropriate to conduct bone conduction testing on young infants without compensating for an occlusion effect; however, for older infants, it is prudent to remove insert earphones during bone conduction testing. For both young and older infants, occluding the ear canal increases the sound pressure near the tympanic membrane; however, this pathway appears to contribute less to bone conduction hearing when ears are occluded compared with adults as measured by ASSRs.

Air-bone gap estimated with multiple auditory steady-state response in young children with otitis media with effusion

Even though many patients undergoing auditory steady-state response (ASSR) testing have some degree of hearing loss, some have normal hearing and ASSR often overestimates the behavioral thresholds in this group. In most commercial ASSR systems such as Chartr EP, a default correction factor is applied to compensate for this difference. Little is known, however, as how the correction factor compensates for the difference between ASSR and pure tone audiometry (PTA) thresholds as a function of carrier or modulation frequency (MF) in a commercial ASSR system. Our goal is to evaluate this relationship. Twenty-four normal hearing adults were examined for both PTA and ASSR (Chartr EP system, GN Otometrics). ASSR thresholds were obtained at three MFs (20, 40, and 80Hz). The difference scores were obtained by subtracting PTA from ASSR thresholds at each frequency for each subject. The corrected ASSR thresholds, then, were compared with the PTA thresholds across MFs and carrier frequencies. The default correction factors in the ASSR equipment differed significantly from the difference scores at all MFs and carrier frequencies (n = 24, p < 0.005). The correlation between corrected ASSR and PTA thresholds at most MFs and carrier frequencies were medium to poor. At most MFs and carrier frequencies, the default correction factors defined by the manufacturer do not compensate for the difference between ASSR and PTA thresholds in normal hearing adults. The use of the default correction factors in Chartr EP system for the normal hearing adults needs special considerations.

Conclusion: The correlations between behavioral and auditory steady-state response (ASSR) thresholds were significant at 500, 1000, 2000, and 4000 Hz. ASSR presented high sensitivity and specificity in the detection of residual hearing in cochlear implant candidates when compared with warble-tone audiometry. Objectives: To assess residual hearing in cochlear implant candidates by comparing the electrophysiological thresholds obtained in dichotic single-frequency ASSR with behavioral thresholds at 500, 1000, 2000, and 4000 Hz. Methods: This was a comparative study between ASSR and warble-tone audiometry thresholds in 40 cochlear implant candidates (80 ears) before cochlear implantation with bilateral severe-to-profound sensorineural hearing loss. Results: Thresholds were obtained in 62.5% of all frequencies evaluated in warble-tone audiometry and in 63.1% in the ASSR. ASSR sensitivity was 96% and specificity was 91.6%. Mean differences between behavioral and ASSR thresholds did not reach significance at any frequencies. Strong correlations between behavioral and ASSR thresholds were observed in 500, 1000, and 2000 Hz and moderate in 4000 Hz, with correlation coefficients varying from 0.65 to 0.81. On 90% of occasions, ASSR thresholds were acquired within 10 dB of behavioral thresholds.