Low-frequency auditory brainstem response threshold

Auditory brainstem thresholds have been determined in 35 non-cooperative, anaesthetized children using a 'two-point audiogram' paradigm. The high-frequency point was found with a 2 kHz tone-burst without masking, and the low-frequency with a 0.5 kHz tone-burst together with 1 kHz high-pass noise masking. Great variability was found in the low-frequency thresholds, and only 3 of 18 ears with normal high-frequency thresholds had low-frequency thresholds below 70 dB nHL. It is concluded that the 0.5 kHz tone-burst with 1 kHz high-pass noise masking is not a reliable method for routine assessment of low-frequency auditory threshold at the brainstem level.     

儿童chirp听性脑干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脑干反应(ABR)测试,观察chirp ABR阈值与行为测听的相关性,探讨chirp ABR作为儿童临床客观听力评估的可行性.方法 选择2007年8月至9月佛山市听觉语言康复中心的听力障碍儿童和广州市儿童医院听力门诊的正常听力儿童共22例(共35耳)作为研究对象,分别进行行为测听和chirp ABR测试,并对chirp ABR反应阈和行为测听阈值进行Pearson相关性分析.结果 22例接受测试儿童中男14例,女8例,年龄3.3～6.5岁,平均年龄4.8岁.纳入研究的35耳中,正常听力6耳,听力损失轻度2耳、中度4耳、重度10耳、极重度13耳.行为测听0.5、1、2、4 kHz平均听阈与chirp ABR阈值,0.5 kHz听阈与L-chirp ABR阈值,1～4kHz平均听阈与U-chirp ABR阈值之间的相关系数分别为0.939,0.900及0.930,P值均<0.05.结论 chirp ABR作为一种客观测听技术,能够较好地反映儿童的听力水平,有希望应用到临床工作中.     

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.     

Maturation of auditory function related to hearing threshold estimations using the auditory brainstem response during infancy

Objective

The objective of this study was to quantify the maturation of the Auditory Brainstem Response (ABR) at discrete periods during infancy and to provide a means to appropriately estimate hearing thresholds when the ABR is immature.

Methods

A longitudinal study was designed to measure the in situ ABR thresholds of infants using air-conduction tone bursts of 500, 2000 and 4000 Hz. Thresholds were measured using an eardrum-level microphone to eliminate the bias related to coupler-referenced scales such as the dB nHL scale used for adult assessments.

Results

The study found that the in situ thresholds of a sample of normally developing infants decreased significantly during the first 6 months of life. A comparison of these in situ thresholds with those of normal-hearing adults revealed that the ABR response reached maturity in these infants between 4 and 6 months of age for the frequencies 500 and 2000 Hz but remained immature, or elevated, at 6 months of age for 4000 Hz.

Conclusions

The maturation of the ABR should be considered during the estimation of an infant's audiogram and subsequent diagnosis.     

Inaccuracies in the measurement of auditory brainstem response data in normal hearing and cochlear hearing loss

In a test-retest experiment inaccuracies in the measurement of the peak latencies and threshold of the auditory brainstem response were determined for a group with normal hearing and for a group with cochlear hearing loss. The inaccuracy of the auditory brainstem response threshold is less than 4 dB in both groups. The inaccuracy in latency was measured as a function of stimulation level. In both groups the latency inaccuracy of peak V varies from 0.1 ms at levels well above threshold to 0.2 ms near the response threshold. Analysis of variance showed that in subjects with normal hearing the intra- and interindividual variabilities of the peak V latencies contribute about equally to the total variance at all stimulation levels. The implications that these findings have for the determination of the horizontal shift of the latency-intensity curve are discussed.     

听性脑干反应与40Hz听觉相关电位综合评估听觉阈值

目的 探索应用听性脑干反应(auditory brain stem response,ABR)和40Hz听觉相关电位(40Hz auditory event related potential,40Hz AERP)来客观评估听阈的最佳方法.方法 对120例受试者分别测出其平均听阈和ABR阈值、40Hz AERP阈值,共获得资料可靠完整的86耳用于实验分析.将86耳根据听力曲线的类型分为下降型29耳、上升型20耳和水平型37耳三种.用SPSS软件分别对3组数据进行统计学处理,并进行多元回归分析,建立三种数学模型,并进行简化和检验.最后另选10例新的受试者对得到的公式进行均方差可靠性检验.结果 3组平均听阈与ABR阈值和40Hz AERP阈值具有显著线性相关性(r2=0.932,0.944,0.934).建立的三种模型分别为:水平型,平均听阈=ABR阈值;下降型,平均听阈=1/3(40HzAERP) 2/3ABR;上升型,平均听阈=2/3(40HzAERP) 1/3ABR.均方差检验显示公式法优于ABR法.结论 利用ABR阈值和40Hz AERP阈值通过三种回归方程较单纯应用ABR阈值能够更准确的估计受试者的平均听阈,可以尝试用于评估婴幼儿及不能主动配合的受试者的听阈.     

Neonatal hearing screening using the auditory brainstem response

A targeted screen of babies at risk of having a sensorineural hearing loss (SNHL) using the auditory brainstem response has been in place since 1987 in Bradford and Airedale. The aims of this paper were to ascertain what proportion of a 4-year cohort of children with SNHL should have been identified by the programme; was identified by the programme; and the reasons for failing when children were missed. The cohort of 49 children had moderate to profound SNHL (> 50 dB) and were born between 1 April 1991 and 31 March 1995. Although 92% had at risk factors (higher than in other series), 80% was the maximum that could have been prospectively detected by the programme and only 37% were actually diagnosed as a result of the screening programme. Apart from a generalised under-recruitment, children with risk factors arising because of in utero, perinatal and postnatal events (as opposed to family history, craniofacial abnormalities and syndromes) tended to be missed (P < 0.01). The overall yield of the screening programme was 0.5/1000/year. While the yield of a universal neonatal screening programme based on otoacoustic emissions should be double this, a targeted infant distraction test later in infancy will be an essential backup. Improved liaison with paediatricians in particular as well as simplification of the referral criteria should improve targeting children at risk.     

Automated system for screening hearing using the auditory brainstem response

Routine screening of hearing using the auditory brainstem response (ABR) in infants, such as neonates in the special care baby unit, requires a system which is quick, user-friendly and gives a simple outcome. A system which consists of a stimulator/amplifier unit for recording the ABR controlled by a standard Master Series BBC Microcomputer is described which fulfils these requirements. The test procedure is highly automated, and a pass or refer decision for the screen on each ear is given by a machine-scoring algorithm which detects the ABR waveform.     

The relation between the pure-tone audiogram and the click auditory brainstem response threshold in cochlear hearing loss

Auditory brainstem response thresholds for 209 ears with cochlear hearing loss were compared with the pure-tone thresholds. It is shown that the pure-tone threshold in the 2- to 4-kHz region has a one-to-one relationship with the auditory brainstem response threshold. Estimating the pure-tone threshold from the auditory brainstem response threshold, the standard error of the estimate is 11 dB. A small part of this estimation error is due to errors in the measurement of the auditory brainstem response threshold and the mean of the pure-tone thresholds at 2 and 4 kHz. The major part is due to unknown factors that are involved in the physiological relationship between the two thresholds.     

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.     

Pediatric hearing assessment by auditory brainstem response in the operating room

Objectives

To investigate the factors contributing to the discrepancies between auditory brainstem response (ABR) thresholds obtained in the operating room (OR) and hearing outcomes obtained in the follow-up period and to explore the benefits and limitations of performing ABR in the OR.

Methods

A retrospective review study was conducted in a pediatric tertiary care facility. A total of 116 patients were identified with complete records, including OR-ABR results, medical examination and surgical procedure notes, and follow-up medical/audiological evaluation. Patients were divided into three groups: (1) 58 patients with middle ear effusion underwent myringotomy and tube placement, (2) 12 patients underwent myringotomy without tube placement, (3) 46 patients underwent ear examination only without effusion found. OR-ABR results were compared to audiological follow-up evaluations and analyzed for each group.

Results

In patients with middle ear effusion and tube placement, the average threshold difference between OR-ABR and follow-up audiological evaluation was 9.7 dB (±12.7), with highest discrepancy of 45 dB. On the other hand, in patients with dry ears and/or no tube placement, the average threshold difference was only 3.8 dB (±8.6). Moreover, the discrepancy was more prominent in patients with mucoid effusion and larger at lower frequency, i.e., 1000 Hz.

Conclusions

The hearing thresholds estimated by ABR testing in the OR can be elevated and follow-up hearing evaluation after tube placement is needed. While ABR testing is valuable in the assessment of pediatric patients, especially for children who are difficult-to-test or have complicated medical conditions, caution should be taken when interpreting OR-ABR results.     

婴幼儿短纯音与短声诱发的听性脑干反应初探

目的分析婴幼儿短纯音诱发的听性脑千反应（tone burst click auditory brain stem response, TB-ABR）与短声诱发的听性脑千反应（click auditory brain stem response, C-ABR）阈值的相关性,以探讨TB—ABR在婴幼儿客观听力评估中的临床应用价值。方法对2007年1月-2009年1月,新生儿听力筛查通过且C—ABR阈值正常者27例（54耳）,以短纯音为刺激声,进行ABR波V反应阈值及潜伏期测试,并与C-ABR作差异与相关性分析。结果本组27例（54耳）婴幼儿中完成4个频率TB-ABR测试的共27例（54耳）,0．5、1、2、4kHz TB—ABR波V反应阈值分别为（40．0±11．6）dBnHL、（36．7±9．0）dBnHL、（27.2±6．7）dBnHL和（25．9±6．3）dB nHL,明显高于C-ABR阈值（17．8±6．4）dBnHL（P〈0．05）,TB-ABR波V反应阑值随着刺激声频率的升高而下降,潜伏期随着刺激声频率的升高而缩短。0．5、1、2及4kHz1BABR反应阈与GABR反应阈的线性相关系数分别为0.53、0．60、0.67、0．72,存在直线正相关关系（P〈0．01）。结论婴幼儿TB-ABR和C-ABR反应阈之间存在相关性,且高频相关性优于低频,TB-ABR可作为一种具有频率特异性的婴幼儿客观听力评估方法。     

State of the art neonatal hearing screening with auditory brainstem response

The purpose of this paper is to briefly review some of the aspects of the auditory brainstem response (ABR) that are important in its use as a method of screening and assessing hearing in the neonate. The paper starts by considering the technical limitations of click ABR and explores the alternative electrophysiological methods. It then considers where ABR is required in the screening of neonates. The role of bone conduction ABR in estimating the conductive component of any hearing loss is discussed. Finally, the ability of the neonatal ABR to predict the long-term audiometric outcome of permanently hearing-impaired children is considered.     

Relationship between the auditory brainstem response and auditory nerve thresholds in cats with hearing loss

This study explored the relationship between the auditory brainstem response (ABR) and auditory nerve sensitivity in cats with normal hearing and with noise-induced permanent threshold shifts. A statistically significant linear correlation was found between each cat's ABR thresholds and the most sensitive single neuron thresholds at the same frequency. ABR thresholds were approximately 25 dB higher than the thresholds of the most sensitive neural responses in cats with normal hearing. The two measures produced equivalent thresholds at impaired frequencies in subjects with sensorineural hearing loss. Two factors may have contributed to this convergence of ABR and neural thresholds. First, our results suggest that the elevation of the most sensitive neural responses led to a compressed threshold distribution. Consequently, only a narrow range of sound levels separated stimulus conditions that activated relatively few fibers from those that were sufficient to evoke a robust population response. In addition, the threshold responses of impaired auditory nerve fibers may have been augmented by activity in the more sensitive 'off-frequency' regions that surrounded a discrete cochlear lesion. Across varying degrees of hearing loss, the ABR maintained a systematic relationship to auditory nerve fiber thresholds, and therefore has the potential to be used as a functional assay of cochlear pathology.     

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.     

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.     

Predictive value of hearing assessment by the auditory brainstem response following universal newborn hearing screening

Abstract

Objective: This study set out to determine the accuracy with which tone pip ABR and click ABR, carried out in babies referred from universal newborn hearing screening, is able to predict the hearing outcome as determined by follow-up hearing tests. Study sample: The cohort of babies studied were all babies referred for hearing assessment from the universal newborn hearing screen in Sheffield, UK for the period January 2002 to September 2007, who were found to have a significant hearing impairment. Design: The results of hearing assessment following referral from the newborn hearing screen were collected together with those of follow-up tests carried out up to an age when behavioural testing had established ear- and frequency-specific thresholds at 0.5, 1, 2 and 4 kHz. Results: The standard deviation of the difference between the follow up and the tone pip ABR thresholds was 10.5 dB for the 4-kHz tone pip, 16.8 dB for the 1-kHz tone pip, and ranged between 21.7 and 24.7 dB for click ABR. Conclusions: The results of the study show that tone pip ABR following referral from newborn hearing screening has a similar accuracy to that reported in older subjects, and is a much better predictor compared to click ABR.     

Visual scoring in the auditory brainstem response. Second report: determination of response threshold

In the ABR audiometry we usually determine the threshold by visual scoring. The evaluation of visual scoring has been investigated in my laboratory for several years, using the traced samples of ABR obtained from 3 normal adults same as that described in my previous report. Stimuli were clicks of 0, 5, 10, 15, 20, 30dBSL and without stimulus. Thresholds were calculated by the two psychophysical methods, "method of limits" and "up and down method". Scorers were two groups: 3 experienced and 3 inexperienced. Results obtained were as follows: 1. In the method of limits, averages of thresholds measured by the experienced scorers were contained 6.0-9.8dB, their standard deviations being 3.82-6.40dB. 84-95% of all thresholds were contained 0-10dB or 5-10dB in the experienced group. 2. In the method of limits, the highest rate that all scorers of a group had the same threshold was 56% in the separate presentation in the experienced group. 3. In the up and down method averages of threshold were contained 4.6-9.1dB, which were smaller than the method of limits, and standard deviations were contained 1.77-3.18dB, which were about 1/2 times in the method of limits. 92-99% of all thresholds were contained 0-5dB or 5-10dB.     

Clinical evaluation of the vector algorithm for neonatal hearing screening using automated auditory brainstem response

A novel auditory brainstem response (ABR) detection and scoring algorithm, entitled the Vector algorithm is described. An independent clinical evaluation of the algorithm using 464 tests (120 non-stimulated and 344 stimulated tests) on 60 infants, with a mean age of approximately 6.5 weeks, estimated test sensitivity greater than 0.99 and test specificity at 0.87 for one test. Specificity was estimated to be greater than 0.95 for a two stage screen. Test times were of the order of 1.5 minutes per ear for detection of an ABR and 4.5 minutes per ear in the absence of a clear response. The Vector algorithm is commercially available for both automated screening and threshold estimation in hearing screening devices.     

Age-related auditory brainstem response (ABR) threshold changes in the dancer mouse mutant

An age-related analysis of auditory brainstem response (ABR) thresholds in 42 heterozygotic dancer mouse mutants (1-13 months old) showed an impairment of ABR thresholds with increasing age, though individual threshold curves could vary considerably. As compared with normal CBA/CBA mice, a progressive deterioration of ABR thresholds occurred from the 2nd postnatal month onwards. The dancer mutant has an inner ear with a morphogenetic type of defect, caused by a semidominant gene which is located in chromosome 19.