儿童频率特异性chirp听性稳态反应与行为测听的相关性

目的采用chirp信号作为声刺激进行听性稳态反应(auditory steady-state response,ASSR)测试,观察chirp-ASSR反应阈值与纯音听阈阈值的相关性,探讨chirp-ASSR客观听力检测在儿童临床听力评估中的价值。方法选取2012年6月至2013年2月中山大学附属第六医院听力中心检测的儿童共40例(共74耳)作为研究对象,在0.5kHz、1.0kHz、2.0kHz和4.0kHz处进行chirp-ASSR和纯音听阈测试,并对结果进行统计学分析。结果 40例接受测试的儿童年龄4-13岁,平均年龄7.7岁。纳入研究的74耳包括男48耳,女26耳;右34耳,左40耳;正常听力59耳,听力损失轻度4耳、中度6耳、重度5耳。0.5-4kHz频率chirp-ASSR反应阈与纯音听阈的相关系数r分别为0.812、0.884、0.842、0.892;chirp-ASSR反应阈经过校正后所得的各频率预估听阈与纯音听阈值更加接近。结论 chirp-ASSR作为一种具有频率特异性的客观测听技术,能够较好的反映儿童真实的听力水平。     

听力损失儿童倍频程CE-Chirp听性脑干反应与行为测听相关性分析

目的　通过比较听力损失儿童倍频程CEChirp听性脑干反应（ABR）反应阈与行为测听阈值的结果差异,探讨倍频程CE-Chirp ABR临床应用的价值。方法  选择21例（共40耳）听力损失儿童,在安静环境下分别测试裸耳倍频程CE-Chirp ABR反应阈与行为测听听阈,将两种不同的测试方法的测试结果进行比较。结果　听力损失儿童倍频程CE-Chirp ABR反应阈与行为测听阈值结果进行统计分析,各频率相关系数r 分别为0.693、0.830、0.836和0.845,P 均<0.05。结论 两种测试方法存在较好的相关性,倍频程CE-Chirp ABR作为一种客观测听技术,对听力损失儿童客观反应具有良好的稳定性和可靠性,能够较好的反映听力水平。     

Click声诱发脑干检测反应阈与行为听阈相关性报告

目的了解听觉脑干诱发电位（ABR）阈值与行为测听阈值之间的相关性,探讨受试者的听力损失程度和频率间的差异对两类测试结果相关性的影响。结合回顾性分析法,对大量样本进行统计分析,试提出一组合理高效的临床声诱发听力检测测试链,以期可准确、快速的获取受试者的听阈,为无法配合听力测试或行为测试结果不可靠的听障儿童的早期听力干预、助听器验配及调试提供可靠的依据。方法对117例（233耳）感音神经性聋患儿分别进行ABR测试及行为测听,记录相应的测试结果进行统计和比较。结果ABR反应阈值较行为测听阈值普遍偏高,且随着受试者听力损失的加重,两者之间的差距逐步缩小;在刺激信号频率为0.5、1.0、2.0和4.0kHz时（包括平均听力）,受试者的ABR反应阈值和行为测听阈值的相关系数分别为0.5591、0.6655、0.7075、0.5675和0.7245,具有显著的相关性（P〈0.01）;同时当受试者的ABR反应阈值处于90dBnHL～100dBnHL之间时,其ABR的反应阈值与行为听阈十分接近,当受试者的ABR反应阈值〉100dBnHL时,其0.5和1kHz处的行为听阈在100～110dB之间,2.0和4.0kHz处的行为听阈在110dB以上。结论ABR反应阈值可较准确的预测听障儿童的听力情况,为无法配合听力测试或行为测试结果不可靠的听障儿童的早期听力干预、助听器验配及调试提供可靠的依据,但建议在Click-ABR的基础上结合Tone-ABR的0.5和1.0kHz用以完整受试者的听力图。     

成人频率特异性chirp听性稳态反应与纯音听阈测试的相关性研究

目的采用chirp信号作为声刺激进行听性稳态反应(auditory steady-state response,ASSR)测试,观察chirp-ASSR反应阈值与纯音听阈的相关性,探讨chirp-ASSR客观听力检测在成人临床听力评估中的价值。方法研究对象包括正常成人组(年龄20～60岁,共计151耳)和感音神经性听力损失组(年龄22～82岁,共计83耳)。在500Hz、1000Hz、2000Hz和4000Hz处进行Chirp-ASSR和纯音听阈测试,并对结果进行统计学分析。结果 0.5～4kHz频率听力正常组Chirp-ASSR反应阈与纯音听阈的相关系数r分别为0.19、0.43、0.58、068;0.5-4.0kHz频率感音神经性听力障碍者的相关系数r分别为0.68、0.84、0.87、0.84;校正后0.5～4kHz各听力组预估听力阈值与纯音听阈的差值较校正前明显缩小。结论在0.5～4.0kHz频率,Chirp-ASSR反应阈与纯音听阈之间存在明显的相关性,在听力损失组中两者的相关性更加显著,而在500Hz处两者的相关性较其它频率低。Chirp-ASSR在客观听力评价中有较好的准确率。     

听性稳态反应和短声诱发的听性脑干反应在客观听阈评估中的作用

目的探讨听性稳态反应(auditory steady-state responses,ASSR)和短声诱发听性脑干反应(ABR)在感音神经性聋人群客观听阈评估中的作用及其在耳聋鉴定中的价值。方法对感音神经性聋组(35耳)及正常组(22耳)分别进行纯音听阈、ABR及ASSR测试,并记录0.5、1、2及4kHz ASSR反应阈(dBHL)、纯音听阈(dBHL)及ABR反应阈(dBnHL)。结果正常组在0.5、1、2、4kHz的ASSR反应阈与纯音听阈相比差异无统计学意义(P>0.05),ABR反应阈与各频率纯音听阈差异有显著统计学意义(P<0.05);耳聋组各频率ASSR反应阈与纯音听阈差异无统计学意义(P>0.05),ABR反应阈与0.5kHz纯音听阈差异有统计学意义(P<0.05),与1、2、4kHz纯音听阈差异无统计学意义(P>0.05)。结论ASSR与ABR联合测试是临床工作中用于客观听阈评估的有效方法。     

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.     

感音神经性聋患儿的听功能综合评估

目的探讨听力测试组合（ABR＋ASSR＋声场环境中的行为测听）在感音神经性聋患儿残余听力评估中的应用价值。方法48名（96耳）感音神经性聋患儿中能配合纯音测听的患儿19人（38耳）设为PTA组,进行纯音测听及ASSR检测;不能配合纯音测听的患儿29人（58耳）设为BA组,进行声场环境中的行为测听（behavior audiometry,BA）、ABR及ASSR检测。结果①PTA组0．5、1、2、4kHz各频率ASSR反应阈与纯音听阈显著相关（P〈0．01）,各频率相关系数分别为0．75、0．76、0．76、0．83,建立本实验室的ASSR—PTA直线回归方程;②BA组23耳ABR无反应但仍可引出ASSR,而ASSR无反应耳ABR均未能引出;BA组29例患儿中ASSR检测反应较好耳（29耳）在0．5～4kHz四个频率上,ASSR可测得83个反应阈值,行为测听可测得89个反应阈值,综合ASSR和行为测听可以得到96个反应阈值。结论与单项听力测试方法相比,听力测试组合（行为测听＋ABR＋ASSR）能为更小年龄、听力损失更重的患儿进行残余听力的评估,同时能对双侧耳间听力差异、各频率的听力损失程度进行评估,为听力损失病变的定位判断提供参考。     

游戏测听与听觉诱发脑干反应评估小儿听力

目的 通过对60例3～6岁感音神经性耳聋小儿听性脑干反应(auditory brainstem response,ABR)与小儿游戏测听(play audiometry,PA)测试结果比较,综合评估小儿听力.方法 选择60例3～6岁门诊患儿,均经声导抗测试及耳声发射测试排除传导性耳聋及听神经病,将60例3～6岁小儿120耳分别进行ABR测试.根据ABR测试结果.选择ABR波V反应阈为50～90 dB nHL的小儿30例为A组,ABR最大输出97 dB nHL未引出波V反应阚的小儿30例为B组;之后两组小儿分别进行游戏测听,将两组的ABR反应阈与游戏测听测试结果进行比较.结果 A组ABR的波V反应阈与小儿游戏测听中2 kHz～4 kHz最小听闻相差均无显著差异:B组ABR最大输出97 dB nHL未引出波V的小儿,游戏测听绝大部分均能获得行为听阈.结论 ABR的波V反应阈与小儿行为测听的高频听阈一致性较好;ABR最大输出97 dB nHL未引出波V的不等于无听力.     

正常豚鼠听性脑干反应与听性稳态反应的对比

目的 比较正常豚鼠听性脑干反应(ABR)和听性稳态反应(ASSR)阈值的差异,为利用豚鼠进行听力学研究提供理论依据.方法 选正常听力豚鼠12只(24耳),在戊巴比妥钠镇静状态下,分别行ABR和ASSR测试.ABR为click刺激声,刺激率为11.1次/s,记录ABR的Ⅱ渡反应阈值.ASSR载波频率(CF)为0.5、1、2、3、4、6 kHz,调制频率(MF)为154 Hz,记录各载频的反应阅值.结果 正常豚鼠ASSR反应阈值高于ABR反应阈值,CF:0.5.4 kHz时.ABR与ASSR阈值间有统计学差异(P<0.01);CF=6 kHz时,两阈值间无统计学差异(P>0.05).结论 正常豚鼠ABR与ASSR阈值间存在较大差值,但ABR与6 kHz的ASSR阈值间无显著差异.故对豚鼠进行听阈评估时,要注意两者间由于ASSR载波频率不同所引起的差异.     

感音神经性聋儿多频稳态诱发电位及短纯音听性脑干反应与行为测听的相关性

目的 比较多频稳态诱发电位（MASSR）、短纯音听性脑干反应（Tb—ABR）与感音神经性聋儿行为测试听阈的差值．研究MASSR和Tb—ABR反应阈与行为听阈之间是否存在相关性以及在不同听力损失聋儿、不同的频率之间的差异。方法 对60名感音神经性聋儿分别测试MASSR和Tb—ABR反应阈和行为听阈，评价MASSR反应阈、Tb—ABR反应阈与行为听阈的相关性。结果 MASSR反应阈、Tb—ABR反应阈和行为听阈之间均有较高的相关性。二者在频率为2、4kHz时，对行为听阈的预测具有相似的、较高的准确性；但在频率为0．5、1kHz时，MASSR的准确性较Tb—ABR高。结论 MASSR和Tb—ABR均可用作感音神经性聋儿言语频率客观听阈的预测，为低龄儿童及难以检测行为听力的患儿提供诊断依据。     

Prediction of frequency-specific hearing threshold using chirp auditory brainstem response in infants with hearing losses

Objectives

To investigate the clinical usefulness of the LS-chirp auditory brainstem response for estimation of behavioral thresholds in young children with mild to severe hearing losses.

Methods

68 infants (136 ears) aged 6–12 months (mean age = 9.2 months) with bilateral mild to severe hearing losses were studied at Children's Hospital of Fudan University. In all cases, the children were referred for LS-chirp ABR and visual reinforcement audiometric (VRA) measurements. The low-frequency band chirp (LF-chirp) thresholds (frequency band = 0.1–0.85 kHz) were compared to the average VRA thresholds (frequency band = 0.25–0.5 kHz), whereas the high-frequency band chirp (HF-chirp) thresholds (frequency band = 1–10 kHz) were compared to the average VRA thresholds (frequency band = 1–4 kHz) using statistical correlation coefficient values.

Results

The LS-chirp ABR thresholds are very close to behavioral hearing levels. The mean differences between chirp-ABR and VRA thresholds were within 5 dB HL for all measurements. The smallest mean threshold difference (<3 dB HL) was obtained for the severe hearing loss group. The correlation coefficient values (r) were 0.97 at low-frequency and high-frequency bands. For each carrier frequency, the best correlations between chirp-ABR thresholds and VRA thresholds were obtained at VRA frequency of 0.25 kHz/LF-chirp (r = 0.98) and VRA frequency of 1 kHz/HF-chirp (r = 0.98).

Conclusions

This study demonstrates the effectiveness using chirp-ABR predicted frequency-specific thresholds, especially of low and middle frequencies. LS-chirp ABR thresholds determined behavioral thresholds in patients with severe hearing losses were better than for mild hearing losses. The use of a chirp-ABR testing ensures higher sensitivity and accuracy than that of auditory stead-state evoked response (ASSR) for measuring frequency-specific thresholds in young children.     

听神经病106例听力学分析

目的 分析106例听神经病患者的临床特点和听力学测试结果.探讨听神经病纯音听力图和听性脑干反应(ABR)的特点.方法 回顾性分析2001年12月至2007年5月就诊的106例(212耳)听神经病患者的症状及纯音听阈、声导抗图及镫骨肌反射、ABR、畸变产物耳声发射(DPOAE)和颅脑影像学检查的结果.结果 患者中男54例,女52例;年龄11～37岁,以青少年居多(75例,70.8%).伴有其他外周神经病者8例,伴视神经病者4例,未查出明确病因者94例.患者均为双耳发病.在212耳中,有173耳(81.6%)听力下降最多的频率为0.25 kHz和0.5 kHz.轻至中度听力损失共209耳(98.6%),均为感音神经性听力损失.按WHO(1997)听阈的均值计算法统计,本组有49耳(23.1%)的听阈≤25 dB,按WHO推荐的听力减退分级标准,使这些有听力障碍的病耳列入了正常范围.212耳听性脑干反应的测试中,各波形皆未引出者124耳(58.5%),余88耳有1或2个波未引出,而可引出的波的波幅很小,但有重复性.在1或2个可引出小波病例中,有23例其另1侧耳各波皆缺失.另有2例伴其他周围神经病和1例伴视神经病的患者,其双耳均有1或2个小波可引出.畸变产物耳声发射除1例左侧3～6 kHz,右侧5～6 kHz未引出外,余均可引出.结论 听神经病在青少年中并不罕见.因听神经病大多以低频听力下降为主,对听神经病患者平均听阈的计算方法值得讨论.     

68例感音神经性耳聋患者ASSR测试听阈与ABR测试V波反应阈的相关性研究

目的旨在探讨ASSR与ABR在诊断感音神经性耳聋中的相关性。方法68例临床诊断为感音神经性耳聋患者分别行0．5kHz，1kHz，2kHz，4kHzASSR测试及ABR测试，进行不同耳别、不同测试频率ASSR阈值与不同耳别ABRV波反应阈之间的相关分析。结果除了0．5kHz ASSR阈值与ABRV波反应阈的相关系数低而无显著意义外，1kHz，2kHz，4kHz ASSR阈值均与ABRV波反应阈有极显著性相关（P〈0．01），且随着测试频率的递增两者的相关系数随之增加，尤其是4kHz ASSR与ABRV波相关系数达到0．95以上（P〈0．01）。结论ASSR诊断感音神经性耳聋是可靠客观的，具有频率特性，可弥补ABR测试在诊断耳聋疾病中的频率局限性。     

Dead regions in the cochlea at 4 kHz in elderly adults: relation to absolute threshold, steepness of audiogram, and pure-tone average

The aims of this study were (1) to investigate the prevalence of dead regions (DRs) at 4 kHz in elderly people with hearing loss and (2) to determine the extent to which the presence/absence of a DR can be predicted from the absolute threshold, the slope of the audiogram, or the pure-tone average (PTA) hearing loss at 0.5, 1, and 2 kHz. DRs were assessed for 98 ears with absolute thresholds between 60 and 85 dB HL at 4 kHz using the threshold equalizing noise test. Thirty-six ears had a DR at 4 kHz. There was no statistically significant difference in the slope of the audiogram or PTA between ears with and without DRs. However, the mean absolute threshold at 4 kHz was significantly higher for the group with DRs than for the group without DRs. The prevalence of DRs exceeded 50% for hearing losses greater than 70 dB.     

Functional hearing loss in children

This report reviewed 39 school-age children diagnosed as having a functional hearing loss utilizing auditory brainstem response (ABR) audiometry during the past 5 years at the Department of Otolaryngology, Kyushu University Hospital in Japan. Twenty-seven cases were females and 12 were males. Seven cases had a hearing loss unilaterally and 32 bilaterally. Although pure-tone audiometry revealed a variety of audiogram shapes, two-thirds of the cases had a flat or saucer-shaped audiogram with a mild to moderately severe hearing loss. ABR audiometry for the frequencies of 1, 2 and 4 kHz indicated a normal hearing threshold in 65 ears of 35 patients, and mild threshold elevations of at least one frequency in the remaining 6 ears of 4 patients. Three illustrative cases were demonstrated, and a discussion was held regarding the features in audiometric tests, and environmental factors surrounding the children with this condition. We emphasized that the physiological hearing measurement such as ABR audiometry should be performed when any discrepancy was noted between the patient's history and results of pure-tone audiometry, because of not infrequent occurrence of functional hearing loss.     

Estimation of the slope of the audiogram with the auditory brain stem response

A practical procedure is described for obtaining frequency specific information with the auditory brain stem response (ABR). ABR thresholds were determined with a 4 kHz sine wave and with a 1 kHz sine wave combined with high pass filtered masking noise (cut-off 2 kHz). The differences between these 2 thresholds were compared with the slopes of the tonal audiogram, in a sample of 30 ears with various kinds of perceptive hearing loss. The test is in conformity with the theoretical knowledge about the ABR, and can be performed in routine practice.     

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。     

Audiometric predictions using stimulus-frequency otoacoustic emissions and middle ear measurements

OBJECTIVE: The goals of the study are to determine how well stimulus-frequency otoacoustic emissions (SFOAEs) identify hearing loss, classify hearing loss as mild or moderate-severe, and correlate with pure-tone thresholds in a population of adults with normal middle ear function. Other goals are to determine if middle ear function as assessed by wideband acoustic transfer function (ATF) measurements in the ear canal account for the variability in normal thresholds, and if the inclusion of ATFs improves the ability of SFOAEs to identify hearing loss and predict pure-tone thresholds. DESIGN: The total suppressed SFOAE signal and its corresponding noise were recorded in 85 ears (22 normal ears and 63 ears with sensorineural hearing loss) at octave frequencies from 0.5 to 8 kHz, using a nonlinear residual method. SFOAEs were recorded a second time in three impaired ears to assess repeatability. Ambient-pressure ATFs were obtained in all but one of these 85 ears and were also obtained from an additional 31 normal-hearing subjects in whom SFOAE data were not obtained. Pure-tone air and bone conduction thresholds and 226-Hz tympanograms were obtained on all subjects. Normal tympanometry and the absence of air-bone gaps were used to screen subjects for normal middle ear function. Clinical decision theory was used to assess the performance of SFOAE and ATF predictors in classifying ears as normal or impaired, and linear regression analysis was used to test the ability of SFOAE and ATF variables to predict the air conduction audiogram. RESULTS: The ability of SFOAEs to classify ears as normal or hearing impaired was significant at all test frequencies. The ability of SFOAEs to classify impaired ears as either mild or moderate-severe was significant at test frequencies from 0.5 to 4 kHz. SFOAEs were present in cases of severe hearing loss. SFOAEs were also significantly correlated with air conduction thresholds from 0.5 to 8 kHz. The best performance occurred with the use of the SFOAE signal-to-noise ratio as the predictor, and the overall best performance was at 2 kHz. The SFOAE signal-to-noise measures were repeatable to within 3.5 dB in impaired ears. The ATF measures explained up to 25% of the variance in the normal audiogram; however, ATF measures did not improve SFOAEs predictors of hearing loss except at 4 kHz. CONCLUSIONS: In common with other OAE types, SFOAEs are capable of identifying the presence of hearing loss. In particular, SFOAEs performed better than distortion-product and click-evoked OAEs in predicting auditory status at 0.5 kHz; SFOAE performance was similar to that of other OAE types at higher frequencies except for a slight performance reduction at 4 kHz. Because SFOAEs were detected in ears with mild to severe cases of hearing loss, they may also provide an estimate of the classification of hearing loss. Although SFOAEs were significantly correlated with hearing threshold, they do not appear to have clinical utility in predicting a specific behavioral threshold. Information on middle ear status as assessed by ATF measures offered minimal improvement in SFOAE predictions of auditory status in a population of normal and impaired ears with normal middle ear function. However, ATF variables did explain a significant fraction of the variability in the audiograms of normal ears, suggesting that audiometric thresholds in normal ears are partially constrained by middle ear function as assessed by ATF tests.     

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.     

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.