三个月婴儿的听性行为反应

目的探索利用行为法对三个月龄婴儿进行听力筛查的可行性。方法对323名北京市区78～104天的婴儿进行了听力检测，测试声为1kHz，90dBSPL和2kHz,90dBSPL两种纯音。给声时观察并用摄像机记录婴儿的听觉行为反应。结果听性行为反应在1kHz,90dB和2kHz,90dB的引出率分别为眼部反应70.6%和71.5%，头部反应39.0%和42.4%，肢体反应82.4%和87.9%，其他反应17.0%和17.3%。结论仅凭上述一种听性行为反应不足以作为听力筛查的依据。若同时观察肢体反应和眼部反应，并以其中之一的引出作为听性行为反应引出的阳性指征，则引出率可达到95%左右，可以满足听力筛查的要求。     

830名0-6岁儿童在安静房间最小听觉反应值分析

目的计算0-6岁儿童在相对安静房间(本底噪声≤45dBA)测听的最小听觉反应值．探讨在非标准测听室进行儿童听力筛查不同年龄组的筛查阳性标准。方法采用行为测听和耳声发射相结合的方法测听。结果在安静房间，测试前被试者对耳声发射均通过的前提下，其测听结果为：1．2．4kHz最小听觉反应值0-3个月≤85 dB SPL；4-6个月≤60dB SPL．7-12月≤55dB SPL；1岁组．2岁组均为55dB SPL；3岁组≤40dB HL ；4岁组、5岁组、6岁组均≤35d BHL。结论根据0-6岁儿童在安静房间测听的最小听觉反应值，可以确定大规模听力筛查不同年龄组儿童的听力筛查阳性标准。     

窄带CE-Chirp声诱发的ASSR在婴儿听力筛查及诊断中的应用

目的探讨窄带CE-Chirp声诱发的听性稳态反应(ASSR)在婴儿听力筛查及诊断中应用的可行性。方法对10例(20耳)耳声发射听力筛查双耳未通过的婴儿(观察组)行ASSR筛查,年龄2～12个月,平均6个月。对照组为10例(20耳)听力正常且耳声发射听力筛查通过的婴儿,年龄为1～11个月,平均6个月。观察组婴儿自然睡眠或测试前口服10%的水合氯醛溶液后进入睡眠,对照组婴儿在自然睡眠下进行测试。应用丹麦国际听力(Inter-acoustics)的EclipseASSR1.02系统,刺激声为窄带(NB)CE-Chirp声,刺激重复率为90次/秒。耳机型号为ER-3A插入式气导耳机。刺激声强度≤80dBnHL时,4个频率双耳同时给声(0.5、1、2、4kHz);刺激声强度>80dBnHL时,单频率双耳给声。初始给声强度为30dBnHL,4个频率都引出反应,判定为ASSR筛查通过;若某个频率未引出,则以20dB一档提高刺激声强度直至引出反应后,再采用降10升5的方法,分别找到每个频率的反应阈。结果观察组10例(20耳)中有2耳(10%)ASSR检查通过,ASSR检查未通过的18耳分别得出500、1000、2000、4000Hz的听阈所用时间为2.4～36.1分钟,平均24.5分钟;对照组10例(20耳)ASSR检查均通过,所用时间为45秒～5.5分钟,平均3.2分钟。结论 NBCE-Chirp ASSR具有快速、特异性高的特点,可用于婴儿听力筛查和频率特异性听力评估。     

声场中记录听性稳态反应

目的 通过扬声器给声,记录正常听力的成人和婴儿的听性稳态反应结果 ,探讨其应用价值.方法 采用AUDIX测试系统,扬声器给声,分别记录睡眠状态下听力正常的成人(18例,年龄20～22岁,平均21.6岁)和婴儿(11例,月龄5～11个月,平均9.5月)的听性稳态反应阈值.结果 正常成人组0.5、1、2、4 kHz 4个频率的反应阈值分别为73.67±3.12、69.72±4.88、68.74±4.45、71.32±3.35 dB SPL;正常婴儿组4个频率的反应阈值分别为77.65±2.36、71.12±3.24、71.80±3.28、72.78±4.12 dB SPL.两组各个对应频率的测试结果 差异无统计学意义(P＞0.05).结论 成人或者婴儿均可以通过扬声器给声来记录听性稳态反应.     

ABR最大声输出无反应儿童的残余听力检测

目的了解听性脑干反应(ABR)最大声输出无反应的听力障碍儿童的残余听力。方法对30例3~6岁双耳ABR最大声输出无反应儿童进行行为测听,分析其结果。结果 1例小儿左耳2 kHz 120 dB HL无反应、4 kHz 115 dB HL无反应;1例小儿右耳4 kHz 115 dB HL无反应;1例小儿右耳0.25 kHz 120 dB HL、0.5 kHz120 dB HL、1 kHz 120 dB HL、2 kHz 120 dB HL和4 kHz 115 dB HL均无反应;其余小儿各频率均获得听阈。30例小儿0.25、0.5、1、2、4 kHz行为听阈检出率为左耳分别为97%、97%、97%、97%、93%,右耳分别为100%、100%、100%、97%、97%。结论 ABR最大声输出无反应的听力障碍儿童绝大部分有残余听力,充分利用和保护其残余听力,可以使极重度听力障碍患儿的听觉言语能力得到不同程度的康复。     

短纯音诱发的听性脑干反应测试中声诱发短潜伏期负反应研究

目的 总结在有听力损失儿童中行短纯音诱发的听性脑干反应(tbABR)测试时记录到的声诱发短潜伏期负反应(acoustically short latency negative response,ASNR)的特点.方法 在有听力损失的0～6岁儿童中应用SmartEP听觉诱发电位仪记录短声和短纯音ABR的反应阈,在记录到ASNR的受试者中分析其反应阈和潜伏期.结果 在所有80受试耳中共7耳(8.75%)在cABR测试中引出ASNR,40耳(50%)在tbABR测试中引出ASNR,其中1 kHz引出率最高(37耳,46.25%),2 kHz次之(25耳,31.25%).引出ASNR者ABR波V反应阈最低65 dB nHL,ASNR反应阈最低80 dB nHL.0.5、1、2和4 kHz短纯音诱发的ASNR潜伏期分别为6～8、5～7、3～5、3～4 ms.随刺激强度的增加,其潜伏期缩短.结论 有听力损失的儿童tbABR测试中可以记录到AS-NR,但不影响以波V反应阈评估听力.     

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.     

婴幼儿听力损失的早期诊断评估及干预*（4）

1．5听力诊断评估听力学诊断评估首要目的是确定有无听力损失,其次是对有听力损失耳的听力损失类型、程度和听力曲线构型进行评估,最后评价整个听觉系统功能的完整性,以便确定干预方法。理想的听力诊断应包括定性、定位、定量和病因诊断,当然听力损失病因诊断在多数情况下还是很难做到。
　　1．5．1“听力正常”的诊断至今对婴幼儿的听力诊断仍然无“听力正常”的标准定义,一般认为ABR反应阈＜30 dB nHL 或 ABR反应阈≤35 dB nHL并DPOAE各频率点或 TEOAE正常引出,同时还要结合家长观察到婴儿有明显的听性行为反应,则可认为听力基本正常;不过最好还是每6个月进行一次复查或告知家长仍需密切关注小儿的日常听性行为反应。     

Logon诱发听性脑干反应

为了解Logon诱发听性脑干反应的频率特异性,在文中以2～8kHz Logon及短声作为刺激声信号,来观察0.25～8kHz纯音听力正常青年人及听力曲线表现为4kHz“V”型下降,而2kHz及8kHz听阈正常青年人的听性脑干反应.结果示听力正常青年人高强度各频率Logon刺激均可引出分化很好的包括5个反应波的波形,其中I、Ⅲ波检出率最高为100%,Ⅳ、Ⅴ波常融合为一个波;听性脑干反应阈4kHz及8kHz较2kHz略低,Ⅰ波潜伏期随频率升高而缩短,Ⅲ波潜伏期缩短轻微,Ⅴ波潜伏期各频率差异无显著性意义,各波波间期随频率升高而延长.听力曲线表现为4kHz“Ⅴ”型下降,而2kHz及8kHz听阈正常的青年人,短声听性脑干反应阈、各波潜伏期、波间期均无明显异常,而4kHz Logon刺激听性脑干反应阈显著升高,2、8kHz Logon刺激听性脑干反应阈基本正常,Logon刺激听性脑干反应阈与纯音听阈线性相关.因此可以认为2～8kHz Logon刺激诱发听性脑干反应具有频率特异性,可做为相应频率听觉敏度测试的客观指标.     

Smad5 基因缺陷导致小鼠听力重度损失

目的 观察Smad5基因敲除小鼠听功能的变化及其特点.方法 50只Smad5基因敲除的杂合子小鼠与25只野生型小鼠分成5组2周、4周、8周、12周、24周组.分别行脑干诱发电位(ABR)检测,刺激声用click及tone burst(8 kHz,16 kHz,32 kHz).结果 Smad5基因敲除杂合子小鼠2周、4周、8周、12周、24周click刺激ABR平均听阈分别为93±2.78 dB SPL;38.7±2.58 dB SPL;64.8±3.78 dB SPL;81.5±2.48 dB SPL;95.7±4.78 dB SPL.野生型小鼠平均听阈分别为99±2.78 dB SPL;38±3.65 dB SPL;32±1.78 dB SPL;32±2.70 dB SPL;47±5.78 dB SPL.经统计学处理,除2周和4周组P＞0.05两者听阈差异无显著性外,其他时间段P＜0.01,说明基因敲除小鼠与野生型小鼠听阈差异有显著性.tone burst(8 kHz,16 kHz,32 kHz)结果与click刺激ABR听阈结果基本一致.结论 Smad5基因敲除导致小鼠随月龄增加而听力损失加重.     

Identification of neonatal hearing impairment: evaluation of transient evoked otoacoustic emission, distortion product otoacoustic emission, and auditory brain stem response test performance

OBJECTIVES: The purpose of this study was to compare the performance of transient evoked otoacoustic emissions (TEOAEs), distortion product otoacoustic emissions (DPOAEs), and auditory brain stem responses (ABRs) as tools for identification of neonatal hearing impairment. DESIGN: A total of 4911 infants including 4478 graduates of neonatal intensive care units, 353 well babies with one or more risk factors for hearing loss (Joint Committee on Infant Hearing, 1994) and 80 well babies without risk factor who did not pass one or more neonatal test were targeted as the potential subject pool on which test performance would be assessed. During the neonatal period, they were evaluated using TEOAEs in response to an 80 dB pSPL click, DPOAE responses to two stimulus conditions (L1 = L2 = 75 dB SPL and L1 = 65 dB SPL L2 = 50 dB SPL), and ABR elicited by a 30 dB nHL click. In an effort to describe test performance, these "at-risk" infants were asked to return for behavioral audiologic assessments, using visual reinforcement audiometry (VRA) at 8 to 12 mo corrected age, regardless of neonatal test results. Sixty-four percent of these subjects returned and reliable VRA data were obtained on 95.6% of these returnees. This approach is in contrast to previous studies in which, by necessity, efforts were made to follow only those infants who "failed" the neonatal screening tests. The accuracy of the neonatal measures in predicting hearing status at 8 to 12 mo corrected age was determined. Only those infants who provided reliable, monaural VRA test results were included in the analysis. Separate analyses were performed without regard to intercurrent events (i.e., events between the neonatal and VRA tests that could cause their results to disagree), and then after accounting for the possible influence of intercurrent events such as otitis media and late-onset or progressive hearing loss. RESULTS: Low refer rates were achieved for the stopping criteria used in the present study, especially when a protocol similar to the one recommended in the National Institutes of Health (1993) Consensus Conference Report was followed. These analyses, however, do not completely describe test performance because they did not compare neonatal screening test results with a gold standard test of hearing. Test performance, as measured by the area under a relative operating characteristic curve, were similar for all three neonatal tests when neonatal test results were compared with VRA data obtained at 8 to 12 mo corrected age. However, ABRs were more successful at determining auditory status at 1 kHz, compared with the otoacoustic emission (OAE) tests. Performance was more similar across all three tests when they were used to identify hearing loss at 2 and 4 kHz. No test performed perfectly. Using either the two- or three-frequency pure-tone average (PTA), with a fixed false alarm rate of 20%, hit rates for the neonatal tests, in general, exceeded 80% when hearing impairment was defined as behavioral thresholds > or =30 dB HL. All three tests performed similarly when a two-frequency (2 and 4 kHz) PTA was used as the gold standard; OAE test performance decreased when a three-frequency PTA (adding 1 kHz) was used as the gold standard definition. For both PTA and all three neonatal screening measures, however, hit rate increased as the magnitude of hearing loss increased. CONCLUSIONS: Singly, all three neonatal hearing screening tests resulted in low refer rates, especially if referrals for follow-up were made only for the cases in which stopping criteria were not met in both ears. Following a protocol similar to that recommended in the National Institutes of Health (1993) Consensus Conference report resulted in refer rates that were less than 4%. TEOAEs at 80 dB pSPL, DPOAE at L1 = 65, L2 = 50 dB SPL and ABR at 30 dB nHL measured during the neonatal period, and as implemented in the current study, performed similarly at predicting behavioral hearing status at 8 to 12     

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.     

Use of a high-risk register in newborn hearing screening.

High-risk newborns were routinely screened for hearing loss by observing their behavioral responses to a 3000-Hz warbled tone at 90 or 100 dB SPL. Infants were identified as high risk if they presented any of the conditions listed by the Joint Committee on Infant Hearing Screening or if they were placed in the special care or intensive care sections of the newborn nursery. During the program's first 12 months, 17% of the total newborn population were included in the screening, and 7% of those screened failed to respond. Approximately half of the infants who failed the screening returned for follow-up testing. No hearing loss has been identified among these infants. Special steps have been required to improve the screening's effectiveness.     

The Effects of Salicylate on Auditory Evoked Potential Amplitwde from the Auditory Cortex and Auditory Brainstem

Tinnitus has often been studied using salicylate in animal models as they are capable of inducing tempo-rary hearing loss and tinnitus. Studies have recently observed enhancement of auditory evoked responses of the auditory cortex (AC) post salicylate treatment which is also shown to be related to tinnitus like behavior in rats. The aim of this study was to observe if enhancements of the AC post salicylate treatment are also present at structures in the brainstem. Four male Sprague Dawley rats with AC implanted electrodes were tested for both AC and auditory brainstem response (ABR) recordings pre and post 250 mg/kg intraperitone-al injections of salicylate. The responses were recorded as the peak to trough amplitudes of P1-N1 (AC), ABR wave V, and ABR waveⅡ. AC responses resulted in statistically significant enhancement of ampli-tude at 2 hours post salicylate with 90 dB stimuli tone bursts of 4, 8, 12, and 20 kHz. Wave V of ABR re-sponses at 90 dB resulted in a statistically significant reduction of amplitude 2 hours post salicylate and a mean decrease of amplitude of 31%for 16 kHz. WaveⅡamplitudes at 2 hours post treatment were signifi-cantly reduced for 4, 12, and 20 kHz stimuli at 90 dB SPL. Our results suggest that the enhancement chang-es of the AC related to salicylate induced tinnitus are generated superior to the level of the inferior colliculus and may originate in the AC.     

Identification of neonatal hearing impairment: summary and recommendations

OBJECTIVES: This article summarizes the results of a multi-center study, "Identification of Neonatal Hearing Impairment," sponsored by the National Institutes of Health. The purpose of this study was to determine the performance characteristics of three measures of peripheral auditory system status, transient evoked otoacoustic emissions (TEOAEs), distortion product otoacoustic emissions (DPOAEs), and auditory brain stem responses (ABR), applied in the neonatal period in predicting hearing status at 8 to 12 mo corrected age. DESIGN: The design and implementation of this study are described in the first two articles in this series. Seven institutions participated in this study; 7179 infants were evaluated. Graduates of the neonatal intensive care unit and well babies with one or more risk factors for hearing loss were targeted for follow-up testing using visual reinforcement audiometry (VRA) at 8 to 12 mo corrected age. Neonatal test performance was evaluated using the VRA data as the "gold standard." RESULTS: The major results of the study are described in the nine articles preceding this summary article. TEOAEs in response to an 80 dB pSPL click, DPOAEs in response to L1 = 65 and L2 = 50 dB SPL and ABR in response to a 30 dB nHL click performed well as predictors of permanent hearing loss of 30 dB or greater at 8 to 12 mo corrected age. All measures were robust with respect to infant state, test environment and infant medical status. No test performed perfectly. CONCLUSIONS: Based on the data from this study, the 1993 National Institutes of Health Consensus Conference-recommended protocol-an OAE test followed by an ABR test for those infants failing the OAE test-would result in low referral rate (96 to 98%). TEOAEs for 80 dB pSPL, ABR for 30 dB nHL and DPOAEs for L1 = 65 dB SPL and L2 = 50 dB SPL perform well in predicting hearing status based on the area under the relative operating characteristic curve. Accuracy for the OAE measurements are best when the speech awareness threshold or the pure-tone average for 2.0 kHz and 4 kHz are used as the gold standard. ABR accuracy varies little as a function of the frequencies included in the gold standard. In addition, 96% of those infants returning for VRA at 8 to 12 mo corrected age were able to provide reliable ear-specific behavioral thresholds using insert earphones and a rigorous psychophysical VRA protocol.     

Distortion-product otoacoustic emissions study of the noise-induced toughening effect in rats

OBJECTIVE: To compare the toughening effects in rats induced by pure tones and a broadband noise (BBN). MATERIAL AND METHODS: Sprague-Dawley female albino rats (n = 148; 8-10 weeks old) were used. Three experimental groups were established as follows. Toughening only: 38 rats, divided into 3 subgroups, were exposed to different conditioning sounds (2 and 4 kHz and a BBN of 0.25-6 kHz, respectively) at 75-85 dB sound pressure limit (SPL) for 8 h/day for 10 days. Acoustic trauma only: 54 rats, divided into 3 subgroups, were exposed to different conditioning sounds as above for 24 h at 100-110 dB SPL. Toughening plus acoustic trauma: 56 rats, divided into 3 subgroups, were exposed to different conditioning sounds as above, followed 8 h later by traumatic exposure to the conditioning sound at 110 dB SPL for 24 h. 2f1-f2 distortion-product (DP) otoacoustic emission measurements were obtained from the right ear of each animal pre-exposure, immediately post-exposure and after 8 h of the traumatic or conditioning exposure. RESULTS: In our control DPgram response, the maximum amplitude occurred at the highest frequencies (2, 3, 4, 5 and 6 kHz). No statistical differences between the control DPgram and the DP toughening (2 and 4 kHz and BBN)responses were found. Only 2 and 4 kHz frequencies induced a protective effect against traumatic sound exposures to the same frequencies, and this finding was statistically significant. CONCLUSION: The toughening phenomenon induced using 2 and 4 kHz pure tones and BBN in rats does not modify the DPgram response. Nevertheless, only 2 and 4 kHz frequencies induce a protective effect against traumatic sound exposures to the same frequencies.     

EEG derivations providing auditory steady-state responses with high signal-to-noise ratios in infants

OBJECTIVE: To identify EEG derivations that yield high signal-to-noise ratios (SNRs) of the auditory steady-state response (ASSR) in infants aged 0 to 5 months. DESIGN: The ASSR was recorded simultaneously from 10 EEG derivations in a monopolar montage in 20 sleeping infants. Stimuli were tones of 0.5 or 2 kHz that were 100% amplitude modulated and 20% frequency modulated, presented at 65 dB SPL for 4.4 minutes in either the right or the left ear. An amplitude modulation frequency of 90 Hz (left ear) or 94 Hz (right ear) was used. From the 10 measured monopolar derivations, all 45 bipolar derivations were calculated mounting up to 55 EEG derivations. EEG derivations were selected in the preferred set if they had the largest SNRs within subjects and if they were obtained significantly more frequently across subjects than was expected by chance (Monte Carlo simulation and Wilcoxon signed ranks test). RESULTS: The preferred derivations are both mastoids ipsilateral to the stimulated ear with Cz as common reference. These derivations improved SNRs compared with each of several conventional EEG derivations (excluding the preferred derivations) between 16 and 69% (500 Hz, left ear), 9 and 132% (500 Hz, right ear), 31 and 193% (2 kHz, left ear), and 3 and 105% (2 kHz, right ear). In contrast to results reported earlier for adults, high SNRs were not found at the inion-Cz derivation in these infants. CONCLUSIONS: High SNRs were obtained in infants aged younger than 6 months if the ASSR was recorded from the mastoids ipsilateral to the ear of stimulation referenced to Cz.     

Distortion-product Otoacoustic Emissions Study of the Noise-induced Toughening Effect in Rats

Objective—To compare the toughening effects in rats induced by pure tones and a broadband noise (BBN). Material and Methods—Sprague–Dawley female albino rats (n=148; 8–10 weeks old) were used. Three experimental groups were established as follows. Toughening only: 38 rats, divided into 3 subgroups, were exposed to different conditioning sounds (2 and 4 kHz and a BBN of 0.25–6 kHz, respectively) at 75–85 dB sound pressure limit (SPL) for 8 h/day for 10 days. Acoustic trauma only: 54 rats, divided into 3 subgroups, were exposed to different conditioning sounds as above for 24 h at 100–110 dB SPL. Toughening plus acoustic trauma: 56 rats, divided into 3 subgroups, were exposed to different conditioning sounds as above, followed 8 h later by traumatic exposure to the conditioning sound at 110 dB SPL for 24 h. 2f1–f2 distortion-product (DP) otoacoustic emission measurements were obtained from the right ear of each animal pre-exposure, immediately post-exposure and after 8 h of the traumatic or conditioning exposure. Results—In our control DPgram response, the maximum amplitude occurred at the highest frequencies (2, 3, 4, 5 and 6 kHz). No statistical differences between the control DPgram and the DP toughening (2 and 4 kHz and BBN) responses were found. Only 2 and 4 kHz frequencies induced a protective effect against traumatic sound exposures to the same frequencies, and this finding was statistically significant. Conclusion—The toughening phenomenon induced using 2 and 4 kHz pure tones and BBN in rats does not modify the DPgram response. Nevertheless, only 2 and 4 kHz frequencies induce a protective effect against traumatic sound exposures to the same frequencies.     

新生儿与成人瞬态诱发耳声发射差异的频谱特性分析

目的 比较新生儿与成人瞬态诱发耳声发射(TEOAE)的差异,并分析其频谱特性.方法 以短声刺激分别对120名通过听力筛查的新生儿(男58,女62)和32名平均纯音听阈(听力级)在20 dB以内的成年人(男15,女17)行TEOAE检测,对于测试结果 行频谱分析和半倍频程分析.结果 ①新生儿组TEOAE总强度(声压级,下同)为(15.18±4.39)dB,高于成人组的(9.51±4.12)dB,差异具有统计学意义(t=9.303,P<0.05).②新生儿的频带重复率、频带重复率非0比例、频带信噪比检出率及频带信噪比在第1频带(0.8 kHz)最低,在3.2 kHz最大;而成人在第5频带(4.0 kHz)处最低,在1.5 kHz最大.③新生儿与成人最大频带信噪比强度差为7.09 dB,二者出现的频率位置相差约1.7 kHz.④半倍频程分析显示新生儿TEOAE最大能量为(10.50±5.09)dB,在2828 Hz处,而成人为(2.84±5.33)dB,在1414 Hz处;二者最大反应在强度上相差7.66 dB,出现的频率位置相差1414 Hz.⑤成人1.5 kHz区的TEOAE信号最强,之后其信噪比随频带增高而降低,而新生儿信噪比却呈现随频带增高而增强的特征;从第1频带到第5频带,新生儿与成人TEOAE强度的差值随频带增高也逐渐增大.结论 成人TEOAE总强度低于新生儿.新生儿频带信噪比及半倍频程能量反应峰的分布频率及反应强度均高于成人.     

Evoked acoustic emissions and cochlear microphonics in the mustache bat, Pteronotus parnellii

In the echolocating bat, Pteronotus parnellii, otoacoustic responses at a frequency of 62 kHz are measurable in the external ear canal during continuous and after transient acoustic stimulation. These responses are interpreted to represent emissions from the cochlea. They can reach an amplitude as large as 70 dB SPL and occur in the frequency range most important for echolocation, namely on the average about 700 Hz above the constant frequency component of the orientation calls. A sharp maximum of the amplitude of cochlear microphonic potentials at about 62 kHz could be correlated with the emission frequency. In one bat an evoked otoacoustic response changed to a spontaneous otoacoustic emission. The frequency and amplitude of the evoked otoacoustic responses reversibly decreased after exposure for 1 min to continuous sounds of more than 85 dB SPL with frequencies of about 2.5-7.5 kHz above the emission frequency. Similar effects occurred during anaesthesia or cooling. A possible relation between the existence of otoacoustic emissions and morphological specializations of the cochlea is discussed.