感音神经性聋患者窄带CE-Chirp ASSR测试结果初步分析

目的探讨感音神经性听力损失患者CE-Chirp声诱发听性稳态反应(auditory steady state response,CE-Chirp ASSR)与纯音听阈各频率反应阈值的相关性。方法选取中、重度听力损失患者18例(30耳)为受试者,听性稳态反应调制频率为90 Hz,分别测试窄带CE-chirp ASSR和纯音听阈500、1000、2000和4000 Hz的反应阈值,并进行相关性分析。结果 0.5-4.0 kHz频率CE-Chirp ASSR反应阈与纯音听阈的的相关系数r分别为0.671、0.704、0.563、0.687(P<0.01)。结论 CE-Chirp ASSR反应阈与纯音听阈有显著相关性,在客观听力评估中有较好的准确性。     

100例婴幼儿TB-ABR与CE-Chirp ASSR结果分析

目的对100例极重度感音神经性听力损失婴幼儿进行短纯音听性脑干反应(tone burst auditory brainstemresponse,tb-ABR)和CE-Chirp声诱发的听性稳态反应(auditory steady-state response,CE-Chirp ASSR)测试,对各频率反应阈的结果进行总结分析,比较两种测试方法的异同点。方法对100例极重度感音神经性听力损失婴幼儿进行短纯音ABR与CE-Chirp ASSR各频率反应阈值的测试,分别记录0.5k、1.0 k、2.0 k和4.0k Hz的反应阈值,所得数据采用SPSS 11.0统计软件进行相关性检验和χ2检验。结果短纯音ABR与CE-Chirp ASSR各频率能引出不同程度的阈值,V波引出阈值百分比主要集中在91~100d BHL,500~4000Hz波V阈值引出率之间的相关系数分别为:0.852、0.911、0.870、0.910,所有P<0.001。CE-Chirp ASSR与短纯音ABR各频率反应阈的χ2检验,P>0.05。。结论短声ABR提示极重度感音性听力损失婴幼儿,其短纯音ABR与CE-Chirp ASSR各频率均有不同程度的残余听力,短纯音ABR与CE-Chirp ASSR各频率反应阈引出率有很好的相关性,耳别间也无显著性差异。     

感音神经性聋成人不同刺激声ASSR反应阈与纯音听阈的相关性分析

目的探讨调制声听性稳态反应(ASSR)、 CE-Chirp ASSR用于评估感音神经性聋成人客观听力的价值。方法对78例(131耳)感音神经性聋成人同时进行纯音听阈和调制声ASSR、 CE-Chirp ASSR测试,比较0.5~4 kHz各频率纯音听阈与调制声ASSR、CE-Chirp ASSR反应阈的相关性及差值。结果 0.5、1、2、4 kHz CE-Chirp ASSR反应阈与纯音听阈的相关系数(分别为0.77、0.73、0.80、0.88)均高于调制声ASSR反应阈与纯音听阈的相关系数(分别为0.64、0.61、0.78、0.84),调制声ASSR、CE-Chirp ASSR反应阈与纯音听阈均具有显著相关性(圴为P<0.01);0.5~4 kHz CE-Chirp ASSR反应阈和纯音听阈的差值(分别为8.09±4.74、10.76±5.86、7.44±7.95、6.11±9.14 dB)均明显小于调制声ASSR反应阈和纯音听阈间的差值(分别为14.31±6.38、13.85±6.25、17.17±6.29、13.58±4.35 dB),差异均有统计学意义(均为P<0.05)。结论 CE-Chirp ASSR快捷可靠,较调制声ASSR能更好地评估感音神经性聋成人的听力。     

婴儿听性稳态反应和听性脑干反应听力评估对比分析

目的 对新生儿听力筛查复筛未通过的婴儿的cABR及ASSR检测资料进行对比分析,了解它们各自的应用限度和相互关系.方法听力筛查复筛未通过,DPOAE、cABR及ASSR检测资料完整的婴儿546耳,男326耳,女220耳,年龄1～12月.分为3组:①听力正常组:DPOAE正常、cABR波V反应阈≤30 dB nHL,146耳;②可疑听力损失组:DPOAE未能引出或部分频率不能引出、即使cABR波V反应阈≤30 dB nHL也列入该组,126耳;③听力损失组:DPOAE正常或不正常、cABR波V反应阈＞30 dB nHL,听力损失组中又按cABR反应阈分为3组:cABR反应阈≤60 dB nHL 153耳、61～97 dB nHL 75耳、无反应46耳.分别计算各组cABR波V反应阈与ASSR的0.5、1、2、4 kHz反应阈的均值和标准差、变异系数,并进行相关性分析.结果 要儿cABR波V反应阈正常平均值为24.7±5.0 dB nHL,0.5、1、2、4 kHz ASSR正常反应阈平均值分别为43.3±11.2、36.9±9.5、28.6±11.8、31.7±14.0 dB nHL.cABR反应阈正常平均值的标准差明显比ASSR小,tAleR变异系数小于ASSR,差异有统计学意义(P＜0.05).cABR最大输出无反应的46耳中ASSR各频率也未引出的有6耳,ASSR各频率都可以引出的有27耳,部分引出的有13耳.结论 ASSR与cABR在婴儿听力评估中起重要的相互补充的作用,运用ASSR加cABR进行综合评估值得推荐.     

相反极性短声所记录的耳蜗微音电位在小儿听神经病诊断中的应用

目的比较听力正常和ABR缺失儿童相反极性短声所记录的耳蜗微音电位(cochlear microphonics,CM)和DPOAE,以探讨它们在小儿听神经病中的诊断价值。方法根据短声ABR阈值、DPOAE和声导抗测试等结果,将受试儿分为听力正常及ABR缺失两组。听力正常组由短声ABR阈值≤30dB nHL、DPOAE正常的54名受试儿(91耳)组成,年龄为1~43月龄,平均为8月龄(中位数4月龄)。ABR缺失组由短声ABR100dB nHL无反应的93名(158耳)受试儿组成,年龄为2~67月龄,平均22月龄(中位数18月龄)。测试状态为水合氯醛镇静睡眠。ABR的刺激声为短声,极性为疏波和密波,刺激速率为19.3次/秒,耳机为ER-3A插入式耳机。听力正常组ABR的分析强度为80dBnHL,ABR缺失组为100dBnHL。结果听力正常组除6耳(6.6%)在80dBnHL未记录到明显的CM外,其余85耳(93.4%)均记录到CM,其时程为0.89±0.19ms。ABR缺失组中24耳记录到CM,其中有12耳(6人)(7.6%)DPOAE正常,有12耳(5人双耳,2人单耳)(7.6%)未记录到DPOAE,该组CM时程为2.61±0.72ms。听神经病在所有ABR缺失病例中的发病率为13.98%。结论CM是一种可靠的评价内耳外毛细胞功能的指标,与DPOAE相比,不易受到其它病理状态的影响。如果不进行CM的测试,可能会将一部分听神经病误诊为耳蜗性听力损失,因此建议对于双耳ABR最大输出无反应、而未记录到DPOAE的婴幼儿病例行CM检查,以避免听神经病的漏诊。     

同步多频听觉稳态诱发反应与听性脑干诱发电位相关性研究

目的探讨同步多频听觉稳态诱发反应(auditory steady-state responses to multiple simultaneous stimuli,MSS-ASSR)与听性脑干诱发电位(auditory brainstem response audiometry,ABR)的关系。方法受试者为不同程度听力损失的儿童70名(140耳),年龄范围为3月龄～6岁。测试状态为水合氯醛镇静睡眠。仪器采用美国INTELLEGENT HEARING的诱发电位仪,MSS-ASSR及ABR测试的软件分别为SMART ASSR和SMART EP,刺激声信号的载波频率为0．5kHz、1kHz、2kHz及4kHz。左耳上述各个载波频率的调制频率分别为77Hz、85Hz、93Hz、101Hz,右耳为79Hz、87Hz、95Hz、103Hz。测试时,双耳八个调幅调制声信号经ER-3A标准插入式耳机同时给出。ABR的刺激声为短声,极性为交替波,刺激速率为19．3次／分,耳机也是ER-3A插入式耳机。受试儿先进行ABR测试、然后进行MSS-ASSR的测试,分别以降10升5法得出二者的反应阈。将MSS-ASSR 0．5kHz、1kHz、2kHz和4kHz的反应阈与ABR反应阈比较,以SPSS 10．0软件进行相关性分析。结果除去58耳ABR无反应外,剩余82耳ABR反应阈与MSS-ASSR 0．5kHz、1kHz、2kHz、4kHz的反应阈相关性具有显著性意义(P=0．000)。Pearson相关系数分别为0．757,0．854,0．906,0．912。结论MSS-ASSR作为儿童听力定量诊断的客观方法有很大的临床应用价值。     

听性稳态反应在新生儿听力评估中的应用

目的 探讨听性稳态反应(auditory steady-state responses,ASSR)在新生儿听力评估中的准确性及应用价值.方法 对30例(60耳)畸变产物耳声发射(distortion product otoacoustic emission,DPOAE)正常的新生儿和45例(78耳)DPOAE异常的新生儿进行ASSR与听性脑干反应(auditory brainstem response audiome-try,ABR)测试,比较ASSR与ABR阈值差异有无统计学意义,并进行两者反应阈的相关性分析.结果 ①DPOAE正常组:ASSR 250 Hz反应阈与ABR阈值差异有统计学意义(P＜0.05),ASSR平均阈值及4 000 Hz反应阈与ABR阈值差异无统计学意义(P＞0.05),ASSR的250、500、1 000 Hz反应阈与ABR阈值相关性不明显,但2 000、4 000 Hz反应阈与ABR阈值有明显的相关性;②DPOAE异常组:ASSR的250～4 000 Hz阈值及平均阈值与ABR阈值差异均无统计学意义(P＞0.05).ASSR各频率反应阈与ABR阈值均有显著的相关性.结论 ASSR可以比较准确地评估听力筛查正常新生儿的平均听阈和中、高频听阈以及听力筛查未通过新生儿的各频率听阈.     

听力筛查AABR未通过而TEOAE通过高危新生儿的听力追踪

目的了解听力筛查AABR未通过而TEOAE通过高危新生儿的听力变化和特点。方法 2008年至2010年对复筛时AABR未通过而TEOAE通过的23例高危新生儿在3月龄时进行听性脑干反应(ABR)、畸变产物耳声发射(DPOAE)以及高频声导抗(high frequency tympanometry,HFT)检查,对ABR异常的患儿在6月龄时复查。结果 3月龄和6月龄时DPOAE各频率基本引出,HFT均为单峰。3月龄时23例患儿中5例双耳ABR反应阈≤35dB nHL,余18例(30耳)单耳或双耳ABR异常,其中8耳可辨出波Ⅰ、Ⅲ、Ⅴ,反应阈40～60dB nHL;15耳只引出波Ⅴ,反应阈70～97dB nHL;7耳97dB nHL声刺激下无波形引出;符合听神经病(auditory neuropa-thy,AN)诊断12例,双耳8例,单耳4例。ABR异常的18例(30耳)6月龄复查时,1耳反应阈≤35dB nHL,29耳反应阈异常,其中,6例(11耳)ABR反应阈降低,1例(2耳)反应阈升高;29耳中14耳可辨出波Ⅰ、Ⅲ、Ⅴ,反应阈40～60dB nHL;11耳只引出波Ⅴ,反应阈70～97dB nHL;4耳97dB nHL未引出波形;符合AN诊断9例,双耳4例,单耳5例。23例患儿1～2岁时电话随访,19例对声音反应良好,2例言语发育稍迟缓,2例2岁时仍不会说话,其中1例合并脑瘫,1例CT示脑白质异常,戴助听器均无效。结论本组听力筛查AABR未通过而TEOAE通过的婴儿听力发展不确定,选择治疗方案需慎重,对这类小儿应长期听力追踪至少到3岁。     

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.     

听性稳态反应对人工耳蜗植入者术前残余听力评估的意义

目的探讨听性稳态反应(ASSR)对极重度聋人工耳蜗植入者听觉功能客观评价的意义。方法回顾性分析41例(82耳)接受人工耳蜗植入的极重度感音神经性聋患儿的耳声发射(OAE)、听性稳态反应(auditorysteady-state response,ASSR)与听性脑干反应(ABR)测试结果。结果所有患儿双耳97dB nHL强度下ABR均未引出反应,DPOAE、TEOAE双耳未引出。ASSR引出率为69.51(57/82),0.25、0.5、1、2、4、8kHz的引出率分别为7.31%、9.76%、10.98%、37.80%、34.15%、8.54%,能引出ASSR患者的反应阈在≤100、100～120dB nHL的分别占68.54%、31.46%。结论 ABR及OAE无反应的极重度感音神经性聋患儿,ASSR大部分能引出反应,可为人工耳蜗植入提供依据。     

Objective assessment of frequency-specific hearing thresholds in babies

OBJECTIVE: To report on clinical experience using dichotic multiple-stimulus auditory steady-state responses (ASSRs) as an objective technique to estimate frequency-specific hearing thresholds in hearing-impaired infants. METHODS: A comparison was made between the click-evoked auditory brainstem response (ABR), auditory steady-state responses and behavioral hearing thresholds (BHTs). Both ears of 10 infants between 3 and 14 months of age were tested. ABR and ASSRs were recorded during the same test session. ABR was evoked by 100 micros clicks. ASSRs were evoked by amplitude- and frequency-modulated tones with carrier frequencies of 0.5, 1, 2 and 4 kHz and modulation frequencies ranging from 82 to 110 Hz. Eight signals (four to each ear) were presented simultaneously. ASSR thresholds were derived after separate recordings of approximately 5, 7.5 and 10 min to compare the influence of test duration. BHTs were defined in later test sessions as soon as possible after the ASSR test, dependent on medical and developmental factors. RESULTS: For the subjects tested in this study 60% of ABR thresholds and 95% of ASSR thresholds for 1, 2 and 4 kHz were found at an average age of 7 months. Only 51% of frequency-specific BHTs could be obtained but on average 5 months later. The correlation of ABR thresholds and ASSR thresholds at 2 kHz was 0.77. The correlation of ASSRs and BHTs was 0.92. The mean differences and associated standard deviations were 4 +/- 14, 4 +/- 11, -2 +/- 14 and -1 +/- 13 dB for 0.5, 1, 2 and 4 kHz, respectively. The average test duration was 45 min for ABR (one threshold in both ears) and 58 min for ASSR (four thresholds in both ears). By reducing the duration of the separate recordings of ASSR, the precision of the hearing threshold estimate decreased and the number of outlying and missing values increased. Correlation coefficients were 0.92, 0.89 and 0.83 for recordings of maximum 10, 7.5 and 5 min, respectively. A compromise between test duration and precision has to be sought. CONCLUSIONS: Multiple-frequency ASSRs offer the possibility to estimate frequency-specific hearing thresholds in babies in a time-efficient way.     

Clinical Comparison of the Auditory Steady-State Response with the Click Auditory Brainstem Response in Infants

Objectives

Our goal was to determine the effectiveness of using the auditory steady state response (ASSR) as a measure of hearing thresholds in infants who are suspected of having significant hearing loss, as compared with using the click-auditory brainstem response (C-ABR).

Methods

We retrospectively analyzed the audiologic profiles of 76 infants (46 boys and 30 girls, a total of 151 ears) who ranged in age from 1 to 12 months (average age: 5.7 months). The auditory evaluations in 76 infants who were suspected of having hearing loss were done via the C-ABR and ASSR. In addition, for reference, the mean ASSR thresholds were compared to those of 39 ears of infants and 39 ears of adults with normal hearing at 0.5, 1, 2, and 4 kHz.

Results

The highest correlation between the C-ABR and ASSR thresholds was observed at an average of 2-4 kHz (r=0.94). On comparison between the hearing of infants and adults at 0.5, 1, 2, and 4 kHz, the mean ASSR threshold in infants was 12, 7, 8, and 7 dB higher, respectively, than that in adults.

Conclusion

ASSR testing may provide additional audiometric information for accurately predicting the hearing sensitivity, and this is essential for the management of infants with severe to profound hearing loss.     

Comparison of threshold estimation in infants with hearing loss or normal hearing using auditory steady-state response evoked by narrow band CE-chirps and auditory brainstem response evoked by tone pips

Objective: The objective of this study is to compare air-conduction thresholds obtained with ASSR evoked by narrow band (NB) CE-chirps and ABR evoked by tone pips (tpABR) in infants with various degrees of hearing loss. Design: Thresholds were measured at 500, 1000, 2000 and 4000?Hz. Data on each participant were collected at the same day. Study sample: Sixty-seven infants aged 4 d to 22 months (median age?=?96 days), resulting in 57, 52, 87 and 56 ears for 500, 1000, 2000 and 4000?Hz, respectively. Results: Statistical analysis was performed for ears with hearing loss (HL) and showed a very strong correlation between tpABR and ASSR evoked by NB CE-chirps: 0.90 (n?=?28), 0.90 (n?=?28), 0.96 (n?=?42) and 0.95 (n?=?30) for 500, 1000, 2000 and 4000?Hz, respectively. At these frequencies, the mean difference between tpABR and ASSR was ?3.6?dB (±?7.0), ?5.2?dB (±?7.3), ?3.9?dB (±?5.2) and ?5.2?dB (±?4.7). Linear regression analysis indicated that the relationship was not influenced by the degree of hearing loss. Conclusion: We propose that dB nHL to dB eHL correction values for ASSR evoked by NB CE-chirps should be 5?dB lower than values used for tpABR.     

Clinical application of dichotic multiple-stimulus auditory steady-state responses in high-risk newborns and young children

Experience with dichotic multiple-stimulus auditory steady-state responses (ASSRs) in clinical practice is described. ASSR thresholds were assessed in a sample of 60 high-risk newborns and young children between birth and 4 years of age. Amplitudes and signal-to-noise ratios (SNRs) of the ASSR were compared between normal-hearing infants and adults. Age-related changes within a group of infants younger than 3 months of age were investigated. A comparison was made between ASSR, the click-evoked auditory brainstem response and behavioral hearing thresholds in infants with a wide range of hearing threshold levels. Mean ASSR thresholds for normal-hearing infants at an average corrected age of 12 days were 42 +/- 10, 35 +/- 10, 32 +/- 10 and 36 +/- 9 dB SPL for 0.5, 1, 2 and 4 kHz, respectively. Compared to adults, these thresholds were elevated by on average 11 dB and SNRs were 1.7 times smaller. However, based on ASSRs, reasonably accurate estimations could be made of behavioral hearing thresholds obtained at a later age (median delay of 7 months). The predicted thresholds were in 61% of the cases within 10 dB of the corresponding behavioral thresholds, and in 83% of the cases within 15 dB. In less than 1 h, thresholds at four frequencies per ear could be obtained. The optimal age of testing is between 1 week and 3 months corrected age. The dichotic multiple-stimulus ASSR technique is a valuable extension of the clinical test battery for hearing-impaired children, as a follow-up diagnostic after the neonatal hearing screening.     

Auditory steady-state responses for children with severe to profound hearing loss

OBJECTIVE: To investigate the clinical usefulness of the dichotic single-frequency auditory steady-state response (ASSR) for estimation of behavioral thresholds in children with severe to profound congenital sensorineural hearing loss. DESIGN: A comparative experimental research design was selected to compare behavioral and ASSR thresholds for the sample. Behavioral pure-tone audiometry served as the criterion standard. SETTING: Hearing Clinic, Department of Communication Pathology, University of Pretoria, Pretoria, South Africa. PATIENTS: A referred sample of 10 patients (20 ears), 5 girls and 5 boys aged 10 to 15 years (mean age, 13 years 4 months), with severe to profound sensorineural hearing impairment. MAIN OUTCOME MEASURES: The difference, and correlation, between 160 pure-tone behavioral and ASSR thresholds at 0.5, 1, 2, and 4 kHz. RESULTS: Mean differences between ASSR and behavioral thresholds were 6 dB for 0.5 kHz and 4 dB for 1, 2, and 4 kHz, with standard deviations varying between 8 and 12 dB. No significant differences (P<.05) were observed between ASSR and behavioral thresholds, except at 0.5 kHz, and Pearson correlation coefficients varied between 0.58 and 0.74 across the evaluated frequencies, with best correlation at 1 kHz and worst at 0.5 kHz. CONCLUSIONS: The ASSR thresholds provided reliable estimations of behavioral thresholds for children with severe to profound hearing loss and indicated an increased sensitivity for more profound hearing loss.     

婴儿多种客观听力检测方法的综合评估

目的探讨多种客观听力检测方法在婴儿听力评估中的应用。方法采用听性脑干反应、40Hz听觉相关电位或听觉稳态反应、畸变产物耳声发射及鼓室声导抗等方法,对初筛和复筛未通过的200例（400例）婴儿进行了听力测试,并对测试结果进行对比分析。结果400耳中各项结果均正常77耳（19．25％）,一项或一项以上检查异常323耳（80．75％）。检查异常的323耳中传导性听力损失59耳（18．27％）,感音神经性听力损失172耳（53．25％）,混合性听力损失92耳（28．48％）。接受听性脑干反应测试的400耳中。正常199耳（49．75％）,异常201耳（50．25％）。以听性脑干反应阈值评估听力损失程度。轻度96耳（47．76％）,中度29耳（14．43％）,重度22耳（10．95％）,极重度54耳（26．86％）。接受40Hz听觉相关电位测试的184耳中,正常52耳（28．26％）,异常132耳（71．74％）。以40Hz听觉相关电位反应阈值评估听力损失程度,轻度68耳（51．51％）,中度34耳（25．76％）,重度14耳（10．61％）,极重度16耳（12．12％）。接受听觉稳态反应测试的216耳中,正常62耳（28．70％）,异常154．1~-（71．30％）。接受畸变产物耳声发射测试的400耳中,正常114耳（28．50％）,异常286耳（71．50％）。接受鼓室声导抗测试的400耳中,正常310耳（77．50％）,异常90耳（22．50％）。结论多种客观听力检测方法的联合运用,对判断婴儿听力损失的程度和性质有一定帮助,可为早期干预提供依据。     

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.     

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.     

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.