Effects of glutamate on distortion-product otoacoustic emissions and auditory brainstem responses in guinea pigs

Objectives To investigate changes in evoked potentials and structure of the guinea pig cochleae during whole cochlear perfusion with glutamate. Methods CM, CAP, DPOAE, and ABR were recorded as indicators of cochlear functions during whole cochlear perfusion. The morphology of the cochlea was studied via transmission electron microscopy. Results There were no significant changes in DPOAE amplitude before and after glutamate perfusion. CM I/O function remained nonlinear during perfusion. ABR latencies were delayed following glutamate perfusion. The average CAP threshold was elevated 35 dB SPL following glutamate perfusion.. The OHCs appeared normal, but the IHCs and afferent dendrites showed cytoplasmic blebs after glutamate perfusion. Conclusions While being a primary amino acid neurotransmitter at the synapses between hair cells and spiral ganglion neurons, excessive glutamate is neurotoxic and can destroy IHCs and spiral ganglion neurons. The technique used in this study can also be used to build an animal model of auditory neuropathy.

Distortion product otoacoustic emissions in newborn babies with and without late-term maternal iron deficiency anaemia

Background:Studies on animals have demonstrated that maternal iron deficiency anaemia(IDA)could result in decreased cochlear sensory hair cells and reduced amplitudes of distortion-product otoacoustic emissions(DPOAEs)of young guinea pigs.Thus,it is essential to study the functioning of cochlear hair cells using DPOAEs in human newborn babies with maternal IDA.The current study explores maternal IDA’s effect on DPOAEs in newborn babies.Method:A total of 110 newborn babies with gestational age≥34 weeks were considered and a‘betweensubjects’design was used.The participants were divided into 3 groups-“Normal”(61 babies without maternal IDA),“Mild”(28 babies with mild maternal IDA)and“Moderate”(21 babies with moderate maternal IDA).The cord blood was collected and the DPOAEs were recorded for each baby for a range of frequencies(1 k 8 kHz)and a range of intensities(7040 dB SPL in 10 dB steps).Results:The analysis of both DP-gram and DP input-output(I/O)function showed that there was no significant difference(p>0.05)across the normal,mild,and moderate groups in the overall presence of DPOAEs as well as the amplitude across frequencies or intensities(7040 dB SPL).Also,the overall correlation of RBC indices with DPOAE amplitude across frequencies as well as the slope of the I/O function showed no relationship.Conclusion:The current study concludes that there is no effect of late-term maternal IDA on the DPOAEs of newborn babies.

Efficient Authentication System Using Wavelet Embeddings of Otoacoustic Emission Signals

Biometrics,which has become integrated with our daily lives,could fall prey to falsification attacks,leading to security concerns.In our paper,we use Transient Evoked Otoacoustic Emissions(TEOAE)that are generated by the human cochlea in response to an external sound stimulus,as a biometric modality.TEOAE are robust to falsification attacks,as the uniqueness of an individual’s inner ear cannot be impersonated.In this study,we use both the raw 1D TEOAE signals,as well as the 2D time-frequency representation of the signal using Continuous Wavelet Transform(CWT).We use 1D and 2D Convolutional Neural Networks(CNN)for the former and latter,respectively,to derive the feature maps.The corresponding lower-dimensional feature maps are obtained using principal component analysis,which is then used as features to build classifiers using machine learning techniques for the task of person identification.T-SNE plots of these feature maps show that they discriminate well among the subjects.Among the various architectures explored,we achieve a best-performing accuracy of 98.95%and 100%using the feature maps of the 1D-CNN and 2D-CNN,respectively,with the latter performance being an improvement over all the earlier works.This performance makes the TEOAE based person identification systems deployable in real-world situations,along with the added advantage of robustness to falsification attacks.

Characterization of spontaneous otoacoustic emissions in 2–4 day old neonates with respect to gender and ear

BACKGROUND： Spontaneous otoacoustic emissions （SOAEs） are regarded as a valuable audio- metric parameter that objectively reflects the function of outer hair cells （OHCs）. Many studies have reported that the incidence of SOAEs in adults is less than 50%. Therefore, measurement of SOAEs may be of little value to clinical examinations. However, the incidence of SOAEs in infants and neonates is higher than in adults. OBJECTIVE： To analyze the basic characteristics of SOAEs in 2–4 day old neonates, and to demonstrate the difference in OHC function between sexes and ears. DESIGN, TIME AND SETTING： Neurophysiological contrast study, performed in the Department of Neonates, Beijing Chaoyang Hospital, Capital Medical University, between December 2007 and August 2008. PARTICIPANTS： A total of 112 newborns （224 ears） consisting of 59 females and 53 males were included in this study. METHODS： The probe was adapted and embedded in the neonate external auditory canal with a foam rubber earplug after checking and clearing up the outer ear canal. The presence of SOAEs was determined when the signal amplitude had a clear peak exceeding –30 dB, or was 3 dB above the noise floor. MAIN OUTCOME MEASURES： The incidence of SOAEs, the number of SOAE signal peaks, and the maximal tension of SOAEs. RESULTS： The incidence in females （79.7%） was higher than males （76.4%） （P 〉 0.05）, and the incidence in right ears （86.6%） was higher than in left ears （69.6%） （P 〈 0.05）. There were no significant difference in the number of SOAE peaks between females and males （4.49 vs. 4.28）, or between right ears and left ears （4.62 vs. 4.12） （P 〉 0.05）. The mean maximum SOAE level per ear in females （–3.29 ± 9.28） dB sound pressure level （SPL） was slightly higher than that in males （–3.91 ± 9.14） dB SPL （P 〉 0.05）. Also, the mean maximum SOAE level in right ears （–2.03 ± 9.11） dB SPL was higher than in left ears （–5.50 ± 9.65） dB SPL （P 〈 0.05）. The maximum SOAE level showed a positive correlation with maximum SOAE number in emitting ears （r = 0.55, P 〈 0.01）. CONCLUSION： The incidence of SOAEs in neonates is high （78.1%） within 4 days of birth. The in-cidence of SOAEs and the maximum SOAE level exhibited a significant difference between right and left ears, but the difference between sexes was insignificant. Both the strongest SOAE signal peak and number of SOAEs per ear are representative of the function OHCs.

Backward Propagation of Otoacoustic Emissions

Normal mammalian ears not only detect but also generate sounds. The ear-generated sounds, i.e., otoacoustic emissions (OAEs), can be measured in the external ear canal using a tiny sensitive microphone. In spite of wide applications of OAEs in diagnosis of hearing disorders and in studies of cochlear functions, the question of how the cochlea emits sounds remains unclear. The current dominating theory is that the OAE reaches the cochlear base through a backward traveling wave. However, recently published works, including experimental data on the spatial pattern of basilar membrane vibrations at the emission frequency, demonstrated only forward traveling waves and no signs of backward traveling waves. These new findings indicate that the cochlea emits sounds through cochlear fluids as compression waves rather than through the basilar membrane as backward traveling waves. This article reviews different mechanisms of the backward propagation of OAEs and summarizes recent experimental results.

Effect of age on click-evoked otoacoustic emission A systematic review

OBJECTIVE：The aims of this study were to investigate the changes of the total intensity of transient evoked otoacoustic emission（TEOAE） and signal-to-noise ratio in various frequency bands as a function of aging,and to explore the role of age-related decline of cochlear outer hair cells.DATA SOURCES：The literature was searched using the PubMed database using ＇transient-evoked otoacoustic emissions＇ as a keyword.Articles were limited as follows：Species was ＇Humans＇;languages were ＇English and Chinese＇;publication date between 1990-01-01 and 2010-12-31.The references of the found were also searched to obtain additional articles.DATA SELECTION：Inclusion criteria：（1） Articles should involve the total TEOAE level or signal-to-noise ratio.（2） The measurement and analysis system used was Otodynamics ILO analysis system（ILO88,ILO92,ILO96 or ILO292）.（3） Studies involved groups of greater than 10 subjects and TEOAE results were from normally hearing ears.（4） If more papers from the same author or laboratory analyzed the same subjects,only one was used.MAIN OUTCOME MEASURES：The correlations of the age scale with the total level and signal-to-noise ratio of TEOAE was determined,respectively.RESULTS：（1） TEOAE total level gradually increased until 2 months of age,and then decreased with increasing age.Significant negative correlations between total TEOAE level and age were found（r =-0.885,P = 0.000）.（2） The most rapid decrease of TEOAE amplitude occurred at 1 year old.The total TEOAE level decreased about 4.25 dB SPL between 2 months to 1 year old,then about 0.26-0.52 dB SPL from 1 year to 10 years old,about 0.23 dB SPL from 11 years to 25 years old,and about 0.14 dB SPL from 26 years to 60 years old.（3） The signal-to-noise ratio in the frequency bands centered at 1.5,2,3 and 4 kHz decreased with increasing age after 2 months of age.Significant negative correlations between the signal-to-noise ratio and age were found for frequency bands ranging from 1.5 kHz to 4 kHz,with the highest correlations at 4 kHz（r =-0.890,P 〈 0.01）,then at 3 kHz（r =-0.889,P 〈 0.01）,at 2 kHz（r =-0.850,P 〈 0.01） and at 1.5 kHz（r =-0.705,P 〈 0.05）.Conversely,a positive correlation between the signal-to-noise ratio centered at 1 kHz and age was found,but was not statistically significant（r = 0.298,P = 0.374）.CONCLUSION：The total TEOAE response level decreased with increasing age after the first 2 months of age.The signal-to-noise ratio also decreased with increasing age in frequency bands above 1.5 kHz.The signal-to-noise ratio in higher frequencies decreased faster than in lower frequencies,leading to the maximum signal-to-noise ratio shift form 3.2-4.0 kHz in neonates to 1.5 kHz in adults,and further decreasing the total TEOAE response level.The age-related TEOAE spectrum peak shift is most likely because the outer hair cells functioning in higher frequencies are more prone to damage than those for lower frequencies.

Isoflurane anesthesia suppresses distortion product otoacoustic emissions in rats

A commonly used anesthetic, isoflurane, can impair auditory function in a dose-dependent manner. However, in rats, isoflurane-induced auditory impairments have only been assessed with auditory brainstem responses; a measure which is unable to distinguish if changes originate from the central or peripheral auditory system. Studies performed in other species, such as mice and guinea-pigs, suggests auditory impairment stems from disrupted OHC amplification. Despite the wide use of the rat in auditory research, these observations have yet to be replicated in the rat animal model. This study used distortion product otoacoustic emissions to assess outer hair cell function in rats that were anesthetized with either isoflurane or a ketamine/xylazine cocktail for approximately 45 min. Results indicate that isoflurane can significantly reduce DPOAE amplitudes compared to ketamine/xylazine, and that responses were more variable with isoflurane than ketamine/xylazine over the 45-min test period. Based on these observations, isoflurane should be used with caution when assessing peripheral auditory function to avoid potentially confounding effects.

Otoacoustic emissions value in patients with idiopathic sudden sensorineural hearing loss

Objectives:This study aimed to determine the prognostic value of otoacoustic emissions(OAEs)in idiopathic sudden sensorineural hearing loss patients.Methods:The study included 30 subjects with unilateral idiopathic sudden sensorineural hearing loss(ISSNHL).Each patient was evaluated four times:at baseline and after one week,one month,and three months of treatment.During each visit,each patient was subjected to full audiological history,otoscopic examination,basic audiological evaluations,and transiently evoked and distortion product otoacoustic emission(TEOAEs&DEOAEs).Results:The hearing thresholds(frequency range 250e8000 Hz)and word recognition scores of patients with detectable TEOAEs and DPOAEs improved significantly,whereas no significant improvements were observed in those with no response.Conclusion:Hearing improvement is better in patients with detectable TEOAEs and DPOAEs.As a result,TEOAEs and DPOAEs are recommended as routine tests in all SSNHL patients to predict outcomes and monitor treatment as TEOAEs and DPOAEs reflect the cochlear OHCs activity.

An Overview of Electrically Evoked Otoacoustic Emissions in the Mammalian Cochlea

Alternating currents injected into the cochlea are able to evoke outer hair cell-mediated basilar membrane motion, thus give rise to production of otoacoustic emissions. This electrically evoked otoacoustic emission(EEOAE) provides a useful tool for the research of out hair cell electromotility in vivo. This article reviews the research work on EEOAEs in mammals. Features of the EEOAEs and theories of their generation are introduced. Methods of EEOAE measurement are also described.

Otoacoustic emissions recorded in people with chronic migraine

Migraine,a moderate to severe chronic headache occurring on one or both sides,is a common disease affects young people.Although hearing loss in subjects with migraine is not rare,the correlation of migraine with hearing loss is not clear.In this study,we examined hearing loss in young migraine subjects to determine if migraine may be a factor in causing cochlear dysfunction.Seven college students with migraine and three age matched subjects without history of migraine were assessed using extended high frequency audiometry and distortion product otoacoustic emissions(DPOAEs).There was no significant difference in regular audiomeiry threshold between the migraine group and the control group.However,high frequency audiometry(9-16 kHz) showed thresholds at 25 dB nHL or higher in six out of twenty ears in the migraine group.The amplitude of DPOAEs were reduced for more than 10 dB in the migraine group in comparison with the control group.These data suggest that migraine may affect cochlear dysfunction evidenced by the reduced amplitude of DPOAE and high frequency pure-tone audiometry.

Spontaneous Otoacoustic Emissions in Tinnitus Patients

Otoacoustic emissions (OAEs) are believed to be the products of active cochlear mechanics. They are generally associated with relatively intact outer hair cell function. OAEs usually decrease or become undetectable when hearing loss of cochlear origin exceeds 40-50 dB HL. Subjective tinnitus is a perception of sound without detectable corresponding source. It is most often seen in patients with hearing loss. It is also frequently seen in patients with head injuries. Studies have suggested that the prevalence of spontaneous otoacoustic emissions(SOAEs) is lower in patients with hearing loss and tinnitus than in normal population. There have also been reports on association between tinnitus and SOAEs of unusually high amplitudes, which can be controlled by aspirin administration. The current paper is a preliminary review of clinical data collected from a group of tinnitus patients in an attempt to elucidate on the relationship between SOAEs and tinnitus from a clinical point of view. Audiometric, tinnitus and SOAE data from 59 patients seen at the Oregon Health & Science University Tinnitus Clinic were retrospectively studied. Fifty-four of these 59 patients showed sensorineural hearing loss of various degrees at the time of evaluation, mostly affecting high frequencies. SOAEs were detected in 26 ears (22%) of 18 patients(30.5%). There was no difference in SOAE prevalence between male and female patients. SOAEs were recorded in four of the five patients whose pure tone thresholds were within normal limits up to 8000 Hz. SOAEs appeared to be recorded at a higher rate in patients whose tinnitus started following motor vehicle accidents or head injuries(5/10) than in other patients. Time course of tinnitus did not appear to affect SOAE detection rate. There were no correlations between SOAE frequency and matched tinnitus pitch or frequency of maximum hearing loss. Significance of these findings is discussed.

Otoacoustic Emissions and Evoked Potentials in Infants after Breast-Feeding Jaundice——Hearing Dysfunction in Breast-Feeding Jaundice

We study hearing in a group of infants with Breast-feeding jaundice (BFJ) by means of Transient-evoked otoacoustic emissions (T-EOE) and Brainstem auditory evoked potentials (BAEP) searching for relationship between bilirubin serum levels and auditory dysfunction. Eleven infants born at-term with BFJ were selected for the study. We studied also 11 control age- and gender matched healthy at-term infants without signs of jaundice. T-EOAE studies were performed between 5-7 days after birth, and 3 months later. BAEP studies were performed once. BFJ group infants exhibited lower amplitudes in T-EOE than infants in the control group. These differences disappear at the 3-month evaluation. In BAEP, we observed a significant latency delay of waves I and V in Breast-feeding jaundice group infants. All infants in both groups demonstrated reproducible wave V response at 30 decibels. No significant correlation values were observed between bilirubin serum levels and T-EOE and BAEP variables. Our data suggest that BFJ can result in transient peripheral and central auditory dysfunction. Dysfunction is reversible after treatment of infants with BFJ.

MEASUREMENT OF AMPLITUDE AND DELAY OF STIMULUS FREQUENCY OTOACOUSTIC EMISSIONS

Although stimulus frequency otoacoustic emissions (SFOAEs) have been used as a non-invasive measure of cochlear mechanics, clinical and experimental application of SFOAEs has been limited by difficulties in accurately deriving quantitative information from sound pressure measured in the ear canal. In this study, a novel signal processing method for multicomponent analysis (MCA) was used to measure the amplitude and delay of the SFOAE. This report shows the delay-frequency distribution of the SFOAE measured from the human ear. A low level acoustical suppressor near the probe tone significantly suppressed the SFOAE, strongly indicating that the SFOAE was generated at characteristic frequency locations. Information derived from this method may reveal more details of cochlear mechanics in the human ear.

Neonatal Hearing Screening Using Transient Evoked Otoacoustic Emission in a Sub-Urban Population in Nigeria

Objective: To determine the proportion of neonates with referral result on testing with transient evoked otoacoustic emission (TEOAE) and the associated risk factors. Method: Prospective evaluation of all neonates born in the Hospital within 6 months using the TEOAE. A hand-held Etymotic Research Otoacoustic Emission Scanner (Ero-scan Combo) was used with the child sleeping in the cot or the mother’s hand. Right and left ears were tested separately and the result was displayed automatically as “pass” when 100% of the in-built criteria were met and “refer” if otherwise. The subjects that passed in both ears were regarded as passes, while those with a refer in either the right/left ears or both ears were regarded as referrals and were thus subjected to rescreening in six weeks or on discharge from the special care baby unit. Analysis was done to find association between the outcome of TEOAE and the clinical and epidemiological risk factors. Result: TEOAE was carried out on 386 neonates, (194 males (50.3%) and 192 females (49.7%)). The mean age at screening was 2.3 days (SD = 1.5), the mean gestational age was 38.0 weeks (SD = 2.7) while the mean birth weight was 2.9 kg (SD = 0.7) and the mean Apgar score at 1 and 5 minute were 8.3 (SD = 1.0) and 9.8 (SD = 0.6). At the first step hearing screening, referral rate was 112 (29.0%);at the second stage, 31 (8.5%) neonates had referral in one or both ears. Fisher’s exact test showed that prematurity, multiple births, jaundice and small birth weight were significantly associated with a referral outcome. However, logistic regression revealed prematurity as a significant predictor of referral outcome with a negative predictive value of 12.61. Conclusion: The referral rate is high with prematurity as a significant predictor. This study calls for commencement of newborn hearing screening and strengthening of the public health measures in the developing countries.

Evaluation of SON’OR^(█),a Medical Device for Provoked Otoacoustic Emissions and Brainstem Evoked Response Audiometry Made in Cameroon

Background: There is a huge gap in the audiological care in Africa by comparison with Western countries. Its main reason is the prohibitive cost of the medical devices used to screen or diagnose patients. A Cameroonian team tackled this problem by developing a medical device (SON’OR©) which integrates a new instrumentation amplifier structure dedicated to perform otoacoustic emissions (OAE) and brainstem evoked response audiometry (BERA). The major technical challenges to perform OAE and BERA are the synchronization and the amplification of signals of very low amplitude. In this work, we emphasize on the general criteria necessary and indispensable to achieve an optimal amplification. The application of a novel instrumentation amplifier structure characterized by its optimized noise factor in the case of BERA and OEA emissions provides simulations and experimental results fully in line with forecasts. The design of SON’OR©is based on general techniques of electronic instrumentation to which we associated the new instrumentation amplifier structure. Objective: To report the clinical evaluation of SON’OR©as a screening and diagnostic tool. Methods: We conducted a cross sectional comparative study in Centre Hospitalier d’Essos in Yaoundé. We tested SON’OR©on two sets of subjects, one for OAE with OTODYNAMICS Echoport ILO 292-II as gold standard and the other for BERA with NEUROSOFT NEURO AUDIO©as gold standard. Each patient was tested with both devices and then we studied the inter device differences and calculated the sensitivity, specificity, positive predictive value and negative predictive value for each test. Results: We got 52 subjects for OEA and 51 for BERA testing. Sex ratio was 1 woman for 2 men in both groups. Mean age was 24.86(SD = 10.53) and 26.33 (10.55) for OAE and BERA groups respectively. SON’OR©had good performances, showing sensitivity of 92.85%/95%, specificity of 96.77%/90.47%, positive predictive value of 95.21%/93.44% and negative predictive value of 95.23%/92.68% for OAE/ BERA respectively. Conclusion: SON’OR©has good characteristics as a medical diagnostic tool. Furthermore its stability and performances in poor electrical conditions make it a robust device really suited for resource limited settings.

常规听力保护下3.0T磁共振噪声对0~12岁儿童听力的影响

目的探究3.0T磁共振(MRI)扫描噪声对儿童耳蜗功能的影响。方法前瞻性纳入2018年5月至11月在我院行头颅MRI检查的儿童72人,采用3M静音海绵耳塞与泡沫隔音头垫进行听力防护。应用免磁性麦克风和声级计对MRI序列的噪声水平(dBA)进行检测。采用畸变产物耳声发射(DPOAE)进行MRI检查前24 h与检查后30 min内2~7 kHz听功能(DPOAE幅值)检查。采用配对t检验或Wilcoxon符号秩检验分析MRI检查前后DPOAE振幅差异。结果研究测得MRI平均噪声水平为(107.70±3.92)dBA。与MRI检查前相比,MRI检查后各频段DPOAE幅值(dB)变化较小,各年龄组振幅差值的变化范围为:0~1岁组左耳(-0.24~1.10),右耳(-0.24~0.74);2~5岁组左耳(-0.07~0.59),右耳(-0.57~0.75);6~12岁组左耳(-0.36~0.44),右耳(-0.30~0.57);且均未见有统计学差异(校正P>0.05)。结论常规听力防护下,未观察到3.0T MRI噪声对儿童耳蜗功能的潜在影响。

职业噪声暴露听力正常人耳蜗突触损伤的研究

目的探究职业噪声暴露下的不同听力学检查方法,对发现常频听力正常人群耳蜗突触损伤的临床意义,为噪声性耳蜗突触病变的研究提供参考。方法选取2021年4月—2022年4月浙江中医药大学健康体检者104例(104耳)为研究对象,按照噪音强度分为接噪组和对照组,每组52例。接噪组接受高强度噪声暴露,对照组接受非噪声暴露,采用纯音测听、噪声下言语测听、畸变产物耳声发射、言语声诱发听性脑干反应4种听力学测试,分析两组各测试结果差异和测试间的相关性。结果对照组在9~16 kHz纯音听阈显著好于接噪组,差异有统计学意义(P<0.01);接噪组噪声下言语测听信噪比损失显著高于对照组,差异有统计学意义(P<0.05);两组畸变产物耳声发射在4~10 kHz比较,差异有统计学意义(P<0.05);两组言语诱发听性脑干反应V、A、O波潜伏期比较,差异有统计学意义(P<0.01),V/A斜率比较,差异有统计学意义(P<0.05)。对照组快速傅里叶变换F1幅值显著高于接噪组,差异有统计学意义(P<0.05);PTAEHF和D波潜伏期与DPmean呈负相关,除了E波其余各波潜伏期均与V/A斜率负相关。结论职业噪声暴露导致可能的耳蜗突触损伤表现为PTAEHF升高,畸变产物耳声发射信噪比下降,噪声下言语识别能力的下降和言语诱发听性脑干反应潜伏期的延迟,联合测试可以提高发现的准确性并及时干预。

耳声发射在早期梅尼埃病和前庭性偏头痛鉴别诊断中的价值初探

目的分析梅尼埃病和前庭性偏头痛的畸变产物耳声发射(DPOAE)特征,探讨DPOAE在二者鉴别诊断中的参考价值。方法纳入在北京同仁医院确诊并连续入组的单侧梅尼埃病患者35例,年龄(41.86±10.77)岁,男21例,女14例;前庭性偏头痛患者32例,年龄(39.97±8.99)岁,男7例,女25例,分析两组纯音听阈和DPOAE的反应幅值及信噪比,并对两组患者中平均听阈正常者进一步对比分析。结果(1)纳入的全部患者中,梅尼埃病组DPOAE在0.7~8 kHz范围内的反应幅值及信噪比均低于前庭性偏头痛组(P均<0.05);(2)平均听阈正常者中,梅尼埃病组在1 kHz处较前庭性偏头痛组的DPOAE信噪比低(Z=-2.495,P=0.013)。结论DPOAE可评估梅尼埃病及前庭性偏头痛患者的耳蜗功能并辅助早期疾病的鉴别诊断。

真人骨导耳声发射影响因素分析

基于双声抑制原理,使用四间隔范式测量刺激频率耳声发射信号以研究真人骨导的耳声发射,分析真人骨导中耳声发射的影响因素。进行了10名正常听力的受试者的刺激频率耳声发射信号的测量实验。实验结果表明,不同刺激强度下测量的刺激频率耳声发射信号频谱幅值不同,其在实验强度范围内随刺激强度的增长而提高;不同持续时间的探测声测量所得的刺激频率耳声发射信号趋势相似;乳突和髁突两个不同刺激位置下的刺激频率耳声发射信号相似,太阳穴处的刺激频率耳声发射信号与其他两个位置有差异。该文在1000∼4000 Hz频率范围内对刺激频率耳声发射的影响因素进行了探索分析,可为骨导的生理特性、经颅衰减、串声消除、响应补偿等研究提供理论基础。

扩展高频纯音测听在噪声性听力损失中的研究进展

听力损失是当今世界最大的致残原因之一,影响世界约1/6人口,其中20%由噪声暴露所致。听力正常者可以听到20 Hz~20 kHz频率的纯音。目前,常规频率(125 Hz~8 kHz)的纯音测听在临床上应用广泛,但扩展高频纯音测听(9~20 kHz)(extended high-frequency audiometry,EHFA),还未成为临床上听力检测的常规项目。越来越多的证据表明,扩展高频纯音测听能够提供如噪声性听力损失、隐性听力损失、言语识别率下降、老年性听力损失等早期听力情况的信息,且灵敏度优于常规频率测听和耳声发射检查。本文对EHFA在噪声性听力损失中的研究进展进行综述。