3种不同条件短纯音诱发听性脑干反应频率特异性观察

目的 :观察比较线性窗短纯音、加宽频带噪声掩蔽的线性窗短纯音及Blackman窗门控短纯音对听性脑干反应 (ABR)频率特异性的影响。方法 :16例听力正常成年人分别接受 3种不同条件短纯音诱发的ABR测试 ,记录各自在 1、2、4kHz不同声强下的ABR波V潜伏期。结果与结论 :① 4、2kHz各刺激声强及 1kHz 70dBnHL以下声强时 ,3种不同条件短纯音有着相同的频率特异性 ;在低频 (1kHz)高声强 (≥ 70dBnHL)时 ,线性窗短纯音因有频谱播散现象而需加用掩蔽噪声来改善频率特异性或需直接采用Blackman窗门控短纯音。②宽频带噪声掩蔽短纯音及Blackman窗门控短纯音在 1、2、4kHz各刺激强度下可获得相同的频率特异性反应 ,但宽频带噪声掩蔽短纯音诱发的反应振幅相对较小 ,因此Blackman窗短纯音更为可取     

Establishing normal hearing with the dichotic multiple-frequency auditory steady-state response compared to an auditory brainstem response protocol

OBJECTIVE: To determine the clinical usefulness of the dichotic multiple-frequency (MF) auditory steady-state response (ASSR) technique for estimating normal hearing compared to a 0.5-kHz tone burst and broadband click auditory brainstem response (ABR) protocol in a sample of adults. MATERIAL AND METHODS: A comparative experimental research design was selected in order to compare estimations of normal hearing obtained with the dichotic ASSR technique at 0.5, 1, 2 and 4 kHz with a 0.5-kHz tone burst and broadband click ABR protocol. The recording times required for each procedure were also compared. Normal-hearing subjects (n = 28) were selected according to immittance values within normal limits and pure-tone behavioural thresholds of < 25 dB HL across frequencies. RESULTS: The dichotic MF ASSR estimated normal hearing to be, on average, 30-34 dB HL across the range 0.5-4 kHz. The mean estimate of normal hearing for 0.5 kHz using tone burst ABRs was 30 dB nHL and the mean click ABR threshold was 16 dB nHL, i.e. 14-18 dB better than the ASSR thresholds. The dichotic MFASSR technique recorded 8 thresholds (4 in each ear) in a mean time of 23 min. The ABR protocol recorded 4 thresholds (2 in each ear) in a mean time of 25 min. CONCLUSION: Both the dichotic MF ASSR and ABR protocols provided a time-efficient estimation of normal hearing. There was no significant difference between the tone burst ABR and MF ASSR techniques in terms of estimation of normal hearing at 0.5 kHz. The dichotic MF ASSR technique proved more time-efficient by determining more thresholds in a shorter time compared to the ABR protocol.     

Effect of audiometric configuration on threshold and suprathreshold auditory steady-state responses

OBJECTIVE: The purpose of this study was to examine the correlation between auditory steady-state response (ASSR) thresholds and behavioral thresholds in hearing-impaired adults with two common audiometric configurations. A second goal was to compare suprathreshold ASSR growth functions in these two subject groups and to determine whether these growth functions could be used clinically to improve threshold estimation. DESIGN: Thirty adults participated, including 10 subjects with normal hearing, 10 subjects with flat moderately severe sensorineural hearing loss, and 10 subjects with sloping high-frequency sensorineural hearing loss. The accuracy of ASSR threshold estimations for the frequencies of 500, 1000, 2000, and 4000 Hz was compared across groups. In addition, ASSRs were recorded at multiple suprathreshold intensity levels, and the growth of the response was compared across subject groups. RESULTS: ASSR and behavioral thresholds were strongly correlated across all subjects, with no significant difference by audiometric configuration. Slightly poorer correlations were obtained in the normal-hearing subjects than in hearing-impaired subjects and for the 500-Hz test frequency compared with the higher stimulus frequencies. Subtraction and regression methods for predicting behavioral thresholds from ASSR thresholds were equally accurate. Suprathreshold amplitude growth was variable among individuals, but mean growth functions showed steeper slopes in hearing-impaired subjects than in normal-hearing subjects, particularly for the higher frequencies (2000 to 4000 Hz). However, there was not a significant difference in the slopes of amplitude growth functions between subjects with sloping versus flat audiometric configurations for these frequencies, and estimation of threshold from suprathreshold ASSR amplitude growth functions was not advantageous. CONCLUSIONS: ASSR thresholds accurately predicted behavioral threshold equally well for flat or sloping audiometric configurations. The accuracy of threshold estimation for either audiometric configuration and the similar growth function slopes may suggest that there is little spread of activation to neighboring regions of the cochlea when using multiple 100% AM stimuli in subjects with moderately sloping losses. The small amplitude of the ASSR response and individual variability may make threshold estimation based on extrapolation from suprathreshold ASSR responses impractical.     

ABR thresholds to tonebursts gated with Blackman and linear windows in adults with high-frequency sensorineural hearing loss

OBJECTIVE: The goal of this study was to determine whether tonebursts gated on and off using a nonlinear, exact-Blackman-gating function would be a more frequency-specific stimulus for auditory brain stem response audiometry than the more traditional 2-1-2 cycle linearly gated toneburst. DESIGN: Toneburst ABRs were recorded in 10 adults with normal hearing and in 18 adults with sloping high-frequency sensorineural hearing loss. It was hypothesized that any advantage of the Blackman stimuli for frequency-specific threshold assessment should be evident in hearing-impaired subjects with hearing loss confined to the 2000 to 4000 Hz frequency region since spectral splatter in the toneburst stimuli could lead to an underestimation of hearing loss based on the ABR thresholds. ABR stimuli consisted of 2000- and 4000-Hz 2-1-2 (rise-plateau-fall) cycle linearly gated tonebursts and 1-0-1 msec exact-Blackman-gated tonebursts. An additional 0.5-0-0.5 msec 4000-Hz Blackman-gated toneburst was used to investigate whether the difference in rise/fall characteristics of the linearly and Blackman-gated tonebursts could account for any differences in ABR results at 4000 Hz. The ABR toneburst stimuli were calibrated behaviorally in 15 adults with normal hearing. RESULTS: In the normal-hearing listeners toneburst-ABR thresholds generally exceeded behavioral thresholds by 10 to 13 dB for all stimuli. Correlations of 0.85 to 0.96 were obtained between 2000 and 4000 Hz toneburst ABR thresholds and pure-tone audiometric thresholds in the hearing-impaired listeners. Results were similar for Blackman- and linearly gated stimuli. CONCLUSIONS: There were no clear differences between Blackman- and linearly gated tonebursts in terms of how well ABR thresholds predicted pure-tone thresholds at 2000 and 4000 Hz. In general audiometric thresholds were predicted with good accuracy (+/-15 dB) by the toneburst ABR thresholds. The 4000-Hz audiometric threshold was underestimated in one subject with a very steeply sloping hearing loss by both Blackman- and linearly gated toneburst ABR thresholds, indicating that ipsilateral masking such as notched noise would be needed to ensure frequency specificity in this and similar cases.     

Steady-state response audiometry in a group of patients with steeply sloping sensorineural hearing loss

OBJECTIVES: The purpose of this study was to examine the predictive value of auditory steady-state response (ASSR) evoked potential thresholds and predicted behavioral thresholds in a group of children with steeply sloping sensorineural hearing loss (HL). STUDY DESIGN: Case series. METHODS: Twenty-nine children with sloping sensorineural HL underwent behavioral audiometric evaluation, impedance testing, distortion product otoacoustic emissions, and steady-state response testing. A t test was performed to compare the means of ASSR predicted behavioral thresholds and behavioral responses. Pearson correlation coefficients were calculated at each tested frequency, 500 Hz, 1,000 Hz, 2,000 Hz, and 4,000 Hz, using the same data. RESULTS: Bracketed thresholds were obtained at 500 Hz, 1,000 Hz, 2,000 Hz, and 4,000 Hz. Nineteen ears were used in this evaluation. A comparison of threshold difference as a function of bracketing revealed that the means were statistically different (P < .05). The mean threshold differences were calculated, and Pearson r values were determined between the behavioral thresholds and the predicted thresholds using the Rance 95 algorithm. The results revealed no difference of means at 500 Hz between predicted and measured behavioral thresholds. Linear regression analysis revealed strong correlation at 500 Hz, 1,000 Hz, and 2,000 Hz. CONCLUSIONS: The GSI Audera appears to predict the configuration of HL in children with steeply sloping sensorineural HLs and over-predicts the severity of the loss by 15 to 20 dB above 500 Hz at each test frequency (1,000, 2,000, and 4,000 Hz). Correlation coefficients display a strong correlation at 500 Hz, 1,000 Hz, and 2,000 Hz.     

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 steady-state response and auditory brainstem response thresholds in children

The inclusion of the auditory steady-state response (ASSR) into test-batteries for objective audiometry has allowed for clinical comparisons with the most widely used procedure, the auditory brainstem response (ABR). The current study describes ASSR and ABR thresholds for a group of infants and young children with various types and degrees of hearing loss. A sample of 48 subjects (23 female) with a mean age of 2.8 ± 1.9 years SD were assessed with a comprehensive test-battery and classified according to type and degree of hearing loss. Thresholds were determined with a broadband click-evoked ABR and single frequency ASSR evoked with continuous tones (0.25–4 kHz) amplitude modulated (67–95 Hz). Mean difference scores (±SD) between the ABR and high frequency ASSR thresholds were 9.8 (±11), 3.6 (±12) and 10.5 (±12) dB at 1, 2 and 4 kHz, respectively. An ASSR mean threshold for 2–4 and 1–4 kHz compared to the ABR threshold revealed an average difference of 7 (±9) and 7.9 (±8) dB, respectively. The overall correlation between the ABR and ASSR thresholds was highest for the mean ASSR thresholds of 2–4 and 1–4 kHz (r = 0.92 for both conditions). Correlations between the ABR and individual ASSR frequencies were slightly less (0.82–0.86). The average of the 2–4 kHz ASSR thresholds correlated best with the click-evoked ABR for all categories of hearing loss except for the sensorineural hearing loss category for which the 1–4 kHz ASSR average was better correlated to ABR thresholds. Findings demonstrate the reliability of verifying high frequency ASSR thresholds with a click-evoked ABR as an important cross-check in infants for whom behavioural audiometry may not be possible.     

Comparison of auditory steady-state responses and auditory brainstem responses in audiometric assessment of adults with sensorineural hearing loss

Objective

Many of the medico-legal patients who claimed compensation may exaggerate hearing loss that varies in degree, nature, and laterality. The purpose of this study was to investigate whether Auditory Steady-State Response (ASSR) could be used to predict the hearing level of adults, and whether ASSR could become a better testing method than Auditory brainstem response (ABR) in audiometric assessment of adults with sensorineural hearing loss.

Methods

This was a prospective study, which was conducted in a tertiary referral hospital. From January to June 2007, 142 subjects (284 ears) with varying degrees of sensori-neural hearing impairment were included in this study. Four commonly used frequencies (500, 1000, 2000, 4000 Hz) were evaluated. All subjects received pure-tone audiometry, multi-channel ASSR, and ABR tests for threshold measurement. The correlation of pure tone thresholds with ASSR and ABR thresholds were assessed.

Results

Between multi-channel ASSR and pure tone thresholds, a difference of less than 15 dB was found in 71% while a difference of less than 25 dB was found in 89% of patients. The correlation coefficient (r) of multi-channel ASSR and pure tone thresholds were 0.89, 0.95, 0.96, and 0.97 at 500, 1000, 2000, and 4000 Hz, respectively. The strength of the relationship increased with increasing frequency. On the other hand, between ABR and pure-tone thresholds, a difference of less than 15 dB was found in 31%; a difference of less than 25 dB was found in 62% of patients. The r correlation value for ABR and pure tone thresholds was 0.83.

Conclusion

ASSR is a more reliable test for the accurate prediction of auditory thresholds than ABR. It can be a powerful and convenient electro-physiologic examination tool for clinically assessing of adults with sensorineural hearing loss.     

Auditory brainstem response (ABR) to tone pips in hearing-impaired children

The correspondence between ABR thresholds to tone pips and behavioral thresholds at 500, 1000 and 2000 Hz was studied in 13 normal and 55 hearing-impaired children, including 42 sensori-neural losses and 13 conductive losses. The children's ages ranged from 1 year 3 months to 8 years. Tone pips were provided with 2-cycle rise-fall times and 2-cycle plateaus. The correlations between the two measures were highly significant at 3 frequencies both in sensori-neural losses and conductive losses. In the subjects with sensori-neural losses, the ABR thresholds tended to be lower than the behavioral thresholds. Mean threshold differences between the ABR and behavioral audiometry at each frequency in sensori-neural losses were 1.6, 0.26 and 5.8 dB, respectively. On the other hand, in the subjects with conductive losses, the ABR thresholds were higher than the behavioral ones by 9.6, 7.8 and 7.5 dB at respective frequencies. Therefore, the hearing acuity in young children with sensori-neural losses can be predicted with accuracy from the ABR thresholds to tone-pips at 500, 1000 and 2000 Hz.     

Estimations of auditory sensitivity for young cochlear implant candidates using the ASSR: preliminary results

This paper presents preliminary results obtained with the use of the auditory steady-state response (ASSR) technique as part of a cochlear implant candidacy assessment protocol for infants Fifteen infants (30 ears), between 10 and 60 months of age, with severe-to-profound hearing loss participated in the study. ASSR measurements were performed for 0.5, 1, 2 and 4kHz at intensities up to 120-128dB HL. The ASSR thresholds were obtained in 74%, of the measurements, and exceeded the maximum auditory brainstem response (ABR) intensity output in 91% of cases and the maximum free-field behavioral intensity output in 84% of cases. Eighty-seven per cent of ASSR threshold measurements were measured at intensities of 100dB HL or higher, and almost half (47%) were measured at intensities of 115 dB HL and higher. Preliminary results indicate that absent ABR and behavioral thresholds do not preclude the possibility of residual hearing, making the ASSR a primary source of information regarding profound levels of hearing loss.     

Frequency-selective auditory brain-stem response in newborns and infants

The efficacy of the frequency-selective auditory brain-stem response (ABR) in new borns and infants was assessed using an auditory stimulus of a 1-kHz tone pip and compared with the results of click-evoked ABR. In subjects whose responses to conventional behavioral audiometry were obtained at intensities of 40 to 70 dB, the ABR thresholds evoked by 1-kHz tone pips and clicks lay between 5 and 20 dB hearing threshold level (HTL). In subjects who did not respond to conventional behavioral audiometry at the intensity of 70 dB, ABR thresholds in each auditory stimulus were elevated by 35 to 70 dB HTL, and no responses were noted at 80 to 90 dB HTL. These results indicate that frequency-selective ABR can be applied clinically as an objective method of audiometry for newborns and infants.     

Estimations of auditory sensitivity for young cochlear implant candidates using the ASSR: preliminary results

This paper presents preliminary results obtained with the use of the auditory steady-state response (ASSR) technique as part of a cochlear implant candidacy assessment protocol for infants. Fifteen infants (30 ears), between 10 and 60 months of age, with severe-to-profound hearing loss participated in the study. ASSR measurements were performed for 0.5, 1, 2 and 4 kHz at intensities up to 120–128 dB HL. The ASSR thresholds were obtained in 74% of the measurements, and exceeded the maximum auditory brainstem response (ABR) intensity output in 91% of cases and the maximum free-field behavioral intensity output in 84% of cases. Eighty-seven per cent of ASSR threshold measurements were measured at intensities of 100 dB HL or higher, and almost half (47%) were measured at intensities of 115 dB HL and higher. Preliminary results indicate that absent ABR and behavioral thresholds do not preclude the possibility of residual hearing, making the ASSR a primary source of information regarding profound levels of hearing loss.     

Using a combination of click- and tone burst-evoked auditory brain stem response measurements to estimate pure-tone thresholds

DESIGN: A retrospective medical record review of evoked potential and audiometric data were used to determine the accuracy with which click-evoked and tone burst-evoked auditory brain stem response (ABR) thresholds predict pure-tone audiometric thresholds. METHODS: The medical records were reviewed of a consecutive group of patients who were referred for ABR testing for audiometric purposes over the past 4 yrs. ABR thresholds were measured for clicks and for several tone bursts, including a single-cycle, Blackman-windowed, 250-Hz tone burst, which has a broad spectrum with little energy above 600 Hz. Typically, the ABR data were collected because the patients were unable to provide reliable estimates of hearing sensitivity, based on behavioral test techniques, due to developmental level. Data were included only if subsequently obtained behavioral audiometric data were available to which the ABR data could be compared. Almost invariably, the behavioral data were collected after the ABR results were obtained. Because of this, data were included on only those ears for which middle ear tests (tympanometry, otoscopic examination, pure-tone air- and bone-conduction thresholds) indicated that middle ear status was similar at the times of both tests. With these inclusion criteria, data were available on 140 ears of 77 subjects. RESULTS: Correlation was 0.94 between click-evoked ABR thresholds and the average pure-tone threshold at 2 and 4 kHz. Correlations exceeded 0.92 between ABR thresholds for the 250-Hz tone burst and low-frequency behavioral thresholds (250 Hz, 500 Hz, and the average pure-tone thresholds at 250 and 500 Hz). Similar or higher correlations were observed when ABR thresholds at other frequencies were compared with the pure-tone thresholds at corresponding frequencies. Differences between ABR and behavioral threshold depended on behavioral threshold, with ABR thresholds overestimating behavioral threshold in cases of normal hearing and underestimating behavioral threshold in cases of hearing loss. CONCLUSIONS: These results suggest that ABR thresholds can be used to predict pure-tone behavioral thresholds for a wide range of frequencies. Although controversial, the data reviewed in this paper suggest that click-evoked ABR thresholds result in reasonable predictions of the average behavioral thresholds at 2 and 4 kHz. However, there were cases for which click-evoked ABR thresholds underestimated hearing loss at these frequencies. There are several other reasons why click-evoked ABR measurements were made, including that they (1) generally result in well-formed responses, (2) assist in determining whether auditory neuropathy exists, and (3) can be obtained in a relatively brief amount of time. Low-frequency thresholds were predicted well by ABR thresholds to a single-cycle, 250-Hz tone burst. In combination, click-evoked and low-frequency tone burst-evoked ABR threshold measurements might be used to quickly provide important clinical information for both ends of the audiogram. These measurements could be supplemented by ABR threshold measurements at other frequencies, if time permits. However, it may be possible to plan initial intervention strategies based on data for these two stimuli.     

Auditory steady state response in pediatric audiology

The main issue regarding pediatric audiology diagnosis is determining procedures to configure reliable results which can be used to predict frequency-specific hearing thresholds.AimTo investigate the correlation between auditory steady-state response (ASSR) with other tests in children with sensorineural hearing loss.MethodsProspective cross-sectional contemporary cohort study. Twenty-three children (ages 1 to 7; mean, 3 years old) were submitted to ASSR, behavioral audiometry, click audiometry brain stem response (ABR), tone burst ABR, and predicting hearing level from the acoustic reflex.Resultsthe correlation between behavioral thresholds and ASSR was (0.70- 0.93), for the ABR tone burst it was (0.73 -0.93), for the ABR click it was (0.83-0.89) only at 2k and 4 kHz. The match between the ASSR and the hearing threshold prediction rule was considered moderate.Conclusionthere was a significant correlation between the ASSR and audiometry, as well as between ABR click (2k and 4 kHz) and for the ABR tone burst. The acoustic reflex can be used to add information to diagnosis in children.     

Auditory sensitivity in children using the auditory steady-state response

OBJECTIVE: To determine the effectiveness of auditory steady-state response (ASSR) as a measure of hearing sensitivity in young children suspect for significant hearing loss. DESIGN: Within-subject comparisons of click auditory brainstem response (ABR) thresholds and ASSR thresholds. SUBJECTS: The study population comprised 42 children suspect for hearing loss and subsequently referred for hearing assessment using electrophysiologic techniques. MAIN OUTCOME MEASURES: Electrophysiologic threshold responses for click ABR and ASSR stimuli (0.5, 1, 2, and 4 kHz) for right and left ears. RESULTS: Based on ABR and ASSR thresholds, 50% of the subjects demonstrated significant hearing loss in the severe to profound range. In some subjects, ASSRs were present at higher stimulus levels when click ABRs were absent. Significant correlations (P<.05) were found between high-frequency ASSR and click ABR thresholds for this study sample. For some subjects, ASSR findings suggested differences between ears that were not observable from the no-response click ABR results. CONCLUSIONS: Auditory steady-state response testing may provide additional information for children who demonstrate hearing levels in the severe to profound range. This information may be helpful when selecting the ear for cochlear implantation for a young hearing-impaired child. Multiple objective methods, such as ABR and ASSR testing, may be needed to determine accurate hearing sensitivity for young children being considered for sensory devices, and in particular, cochlear implants.     

正常新生儿和婴儿的短音听性脑干反应和听觉稳态反应

目的 建立听力正常婴儿短音听性脑干反应(tone-pip ABR)和听觉稳态反应(auditorysteady state response,ASSR)反应阈的正常参考值,研究其听觉发育的生物学规律,并比较两种听力检测技术的频率特性.方法 选取0～6月龄听力正常婴儿80例(160耳),按月龄分为四组:新生儿组、42 d组、3月龄组和6月龄组,每组20例(40耳),男女例数均等,分别记录其短声ABR的潜伏期及在0.25、0.5、1、2、4、8 kHz频率范围内tone-pip ABR和ASSR的反应阈.结果 在70 dB正常听力级短声刺激下,短声ABRⅠ、Ⅲ、Ⅴ波潜伏期、Ⅰ～Ⅲ、Ⅲ～Ⅴ、Ⅰ～Ⅴ波间期随月龄增加逐渐缩短,波Ⅰ于42 d前、波Ⅲ于3个月前发育变化显著.tone-pip ABR波形与短声ABR相似,Ⅰ、Ⅲ、Ⅴ波潜伏期随频率增加逐渐缩短,波形分化逐渐清晰.不同频率、不同月龄tone-pip ABR和ASSR反应阈差异具有统计学意义(P值均＜0.05).除0.25 kHz外,其余频率tone-pip ABR反应阈均低于ASSR.不同月龄tone-pip ABR和ASSR听力曲线形状相似.结论 0～6月正常婴儿tone-pip ABR的潜伏期和波间期随月龄增加逐渐缩短,而反应阈无明显变化.tone-pip ABR和ASSR均有稳定的频率特异性,tone-pip ABR反应阈低于ASSR,可能更接近主观纯音听阈.     

Thresholds determined using the monotic and dichotic multiple auditory steady-state response technique in normal-hearing subjects

Auditory steady-state responses (ASSRs) were elicited by presenting single or multiple, 77-105 Hz amplitude-modulated 0.5, 1, 2, and 4 kHz tones to one or both ears. Objectives of this study were to (i) replicate and extend previous multiple ASSR studies in a quiet double-walled sound booth, and (ii) discover differences (if any) between thresholds assessed in monotic and dichotic conditions, which ranged between 15 and 22dB SPL. The present study's behavioural and ASSR thresholds are 0-10 dB lower (better) than results of previous monotic studies. Further, there are no significant differences in ASSR thresholds between dichotic and monotic stimulus conditions. Therefore, dichotic multiple AM tone stimulation does not produce a change in the ASSR that affects threshold estimation in a clinically significant manner. Thus, at least for detecting normal hearing, the dichotic multiple ASSR technique is a feasible method for estimating hearing thresholds that would substantially reduce recording time compared to conventional single-stimulus techniques.     

The auditory steady-state response: clinical observations and applications in infants and children

Two studies illustrate the use of the auditory steady-state response (ASSR) in the pediatric clinical audiology setting. A protocol for estimating bone-conduction thresholds from ASSR was developed. Bone-conducted narrow-band noise was used to mask the ASSR for a 1.0-kHz modulated tone. The amount of bone-conducted noise needed to mask the ASSR may distinguish between infants and children with conductive hearing losses and those with sensory losses. The amount of bone-conducted noise may also be used to estimate bone-conduction thresholds; however, the accuracy of this technique needs verification with behavioral methods to determine thresholds for bone-conducted pure tones in infants. When ASSR tests are used as part of the diagnostic evaluation for infants and children at risk for hearing loss, the results yield information about the audiometric contour and residual hearing, which aid in treatment and habilitation decisions.     

60例军校男女学员ASSR测试研究

目的旨在观察正常年轻人多频稳态诱发电位（ASSR）测试的正常值特点。方法对60例第一军医大学学员行ASSR、ABR和电测听测试，比较男．女及左、右耳测试值的差异。结果ASSR0．5kHz、1kHz、2kHz、4kHz测试值均数与纯音听闻均数各频率的差值分别为13．86dBHL、14．63dBHL、13．06dBHL．15．28dBHL；ASSR0．5kHz、1kHz、2kHz、4KHz测试值均数与ABRV波反应阈的差值分别为6．14dBHL、5．37dBHL、6．94dBHL、4．72dBHL；男、女学员ASSR测试值比较无显著性差异（P〉0．05）。结论ASSR正常值不受性别．耳别的影响；用ASSR测试值来推断预估纯音听阈．ABRV波反应阈要综合考虑各频率的差值。     

Aided auditory steady-state responses in infants

Infants with hearing loss routinely receive hearing aids several months before reliable behavioral responses to amplified sound can be observed. This necessitates objective measures to validate hearing-aid fittings. A single report has demonstrated the use of ASSRs to determine aided thresholds in children but data in young infants is still lacking. The current study explored aided ASSR compared to unaided ASSR thresholds and subsequent behavioral thresholds in a group of six young infants with hearing loss who received hearing aids between three and six months of age. Aided ASSR thresholds were obtained in 83% of frequencies where aided behavioral thresholds were obtained, with a mean threshold difference of 13±13 dB. The aided ASSR-based threshold estimates were within 15 dB of behavioral thresholds in 63% of cases, indicating a moderate correlation (r = 0.55). Comparing aided and unaided ASSR measurements revealed an average functional gain of 36±15 dB. These results indicate that ASSRs can provide the first evidence of robust hearing aid benefit in young infants several months before behavioral responses are observed.