Evoked otoacoustic emissions: normative data and presbycusis

Evoked acoustic emission (EAEs) recordings hold some promise as a fast, objective and non-invasive audiological procedure to study the cochlea at the outer hair cell (OHC) level. However, accurate interpretation in the EAE response must be based on a knowledge of its variations with age. In order to investigate age-related changes of EAEs, the properties of EAEs (incidence, threshold and spectrum) were studied in 151 ears from subjects whose age varied between 2 and 88 years. EAEs were present in 100% of the tested subjects until the age of 60 years. After this age, EAE incidence fell to 35%. EAE threshold did not vary until the age of 40 years but increased linearly after this age. Thus, complementary information on OHC degenerative changes in presbycusis could be deduced from these data.     

Evoked otoacoustic emissions and sensorineural hearing loss

Following Kemp's original studies, several others have confirmed the existence of otoacoustic emissions. Their clinical relevance remains, however, to be clarified. The various published studies have concerned small series. This study sought to specify otoacoustic emission characteristics in relation to sensorineural hearing loss (148 ears of 76 subjects). The results show that the presence of otoacoustic emissions drops as a function of hearing loss and that there is a highly statistically significant correlation between otoacoustic emission threshold and hearing loss at the 1000-Hz frequency. Otoacoustic emissions are never found when hearing loss at 1000 Hz exceeds 40 dB hearing level and when the mean audiometric hearing loss (at 500, 1000, 2000, and 4000 Hz) exceeds 45 dB hearing level. The main practical conclusion is that otoacoustic emission presence indicates middle frequency functional integrity of the outer hair cells of Corti's organ. Absence of otoacoustic emissions is harder to interpret.     

Evoked otoacoustic emissions: a fundamental and clinical survey

Evoked otoacoustic emissions (EOAEs) hold some promise as a fast, objective and noninvasive procedure to study the cochlea at the outer hair cell level. This paper summarizes the fundamental aspects of EOAEs, in particular their relationship with the active biomechanical properties of the cochlea. The properties of EOAEs are analyzed in normally hearing ears, in ears with sensorineural hearing loss, especially in Ménière's disease, in acoustic neuromas and in central deafness; the properties of EOAEs were also evaluated as to their suitability for screening auditory dysfunction in infants.     

Evoked otoacoustic emissions from normal-hearing young Chinese

Evoked otoacoustic emissions (EOAE) were recorded in normal-hearing young Chinese. Incidences and thresholds of EOAE responses, interaural threshold differences and latencies were calculated. The results were compared with other reports in the literature. The average threshold of EOAEs evoked by 1 kHz bone-conducted tone-burst stimuli was found about 4.43 dB below the subjective thresholds for the stimuli. This result is quite different from that reported by Rossi in 1988. The cause of the result is yet not clear.     

Evoked otoacoustic emissions as cochlear Bragg reflections

The reflection of cochlear waves is mathematically described for various assumptions about the dependence of the echo-generating mechanism on place and frequency, without requiring knowledge of the physical details of the mechanism. Any 'wave-related' reflections, caused by intrinsic features of the resonance or active-feedback mechanism, cannot explain long group delays in an approximately shift-similar basilar membrane (BM). Only 'BM related' scattering due to inhomogenities is a possible explanation then. Reflection at a fixed point of the BM could cause only narrow-band evoked otoacoustic emissions (EOAEs). Long group delays in a wider frequency band can be obtained by assuming Bragg reflection at an approximately periodic inhomogenity of BM parameters, possibly due to spatial variations of active undamping. This explains the long delays, about inversely proportional to frequency, the decreasing instantaneous frequency, the often found multi-packet or modulated structure of echoes (vanishing at higher SPL), the spectra of simultaneous and delayed EOAEs and their relation to the threshold of hearing. These phenomena do not necessarily require multiple reflection due to middle/inner-ear mismatch.     

Evoked otoacoustic emissions in newborn hearing screening

Evoked otoacoustic emissions (EOEs) were recorded in a group of normally hearing neonates (n= 100 ears) to study the basic properties of EOEs and the parameters influencing them. The results obtained with EOE recordings were compared with those of behavioral screening investigations. The main properties of EOEs in neonates are: 1. EOEs can be recorded in 98% of the tested ears or neonates; 2. there were no statistically significant variations in EOE detection thresholds of neonates between the ages of 1 and 4 days; 3. no statistical difference in the EOE threshold was found between males and females; 4. all EOEs exhibited a broadband spectrum with high-component frequencies; 5. EOEs demonstrating narrowband frequency peaks superimposed on the broadband component had detection thresholds lower than EOEs without narrowband frequency peaks. EOEs can be used as a screening test. The main clinical interest of this test is to detect the presence (i.e, normal auditory peripheral function) or the absence (i.e., pathological peripheral auditory function) of EOEs in response to a 30-dBHL click stimulation. The results of this study have important applications concerning the possible clinical use of EOEs for screening peripheral auditory dysfunction in neonates.     

Evoked otoacoustic emissions in infant hearing screening

The main application of the ILO88 otodynamic otoacoustic analyser is clearly in detecting whether the peripheral auditory system is normal or pathological. The evoked otoacoustic emission technique in normal and hearing-impaired children for which audiometric data were known (n = 422 ears) was first performed. The correlation was excellent. The actual experimental group (n = 258 ears) consisted of children who are difficult to test with the conventional screening methods in school health services. The use of evoked otoacoustic emissions as screening instrument is new, and therefore several minimal practical criteria, advantages and limitations were defined. The evoked otoacoustic emission test tool is especially applicable in difficult to test children using conventional screening methods.     

Evoked otoacoustic emissions in guinea pig: basic characteristics

Different types of evoked otoacoustic emissions (EOAEs) such as stimulus frequency emissions, tone burst and click EOAEs, were investigated in the guinea pig. Their correlates on cochlear microphonic potential were also recorded. Although it was confirmed that click EOAEs are difficult to detect in the guinea pig, partly because their delay (2 to 3 ms, measured on tone burst EOAEs) is much shorter than in man, other types of OAE were found in the interval (1.5-5 kHz) for almost every normal animal. Many of their properties were quite different from man, for instance their small number, low level, and the wide frequency range of some of them (up to 500 Hz), suggesting that they represent a sort of continuum. It is proposed that these particularities may not arise from different generating mechanisms but should be correlated with the well-known differences in hair cells patterns.     

Evoked otoacoustic emissions in patients with acoustic neuromas

Click-evoked otoacoustic emissions were recorded in 28 patients with surgically proven acoustic neuromas and 22 patients with brain stem pathologic disorders. Data collected in acoustic tumor ears were compared with those obtained in 30 nontumor ears demonstrating sensorineural hearing losses. Acoustic emissions were altered (increased detection-threshold or no detectable emissions) in all ears with eighth nerve tumors and were not affected in those with brain stem pathologic conditions that do not involve cochlear function. The properties of acoustic emissions were similar in both tumor and nontumor ears with hearing loss, which suggests that acoustic tumors usually produce a cochlear hearing loss.     

Evoked otoacoustic emissions for hearing screening in infants

The early detection of auditory dysfunction in neonates and infants is important for the development of language and other cognitive abilities. The registration of evoked otoacoustic emissions is a new way of detecting cochlear hearing disorders. Results in high-risk infants are reported. Evoked otoacoustic emissions promise to be a fast and noninvasive technique to screen auditory dysfunctions in newborns and high-risk infants.     

Evoked otoacoustic emissions in sensorineural hearing impairment: its clinical implications

This study was performed for the purpose of determining whether or not evoked otoacoustic emissions are useful as a clinical test. Two hundred and twenty-six sequences of the emission in response to stimulus tone bursts were averaged. The detection threshold of the emission was elevated in ears of inner ear impairment with profound sensorineural hearing loss, such as inner ear anomaly, mumps deafness, or sudden deafness, but it was not observed in ears of functional deafness. The mean interaural differences of emission threshold were near 35 dB in unilateral inner ear impairments with profound hearing loss. There was a positive correlation between the interaural difference of audiometric threshold and that of emission threshold in sudden deafness ears with various degrees of hearing loss. The incidence of continuous emission, whose duration was longer than 6 msec, was 30% in normal hearing ears and it was close to 90% in ears with bilateral or unilateral dip type hearing loss. The result was verified in a survey of a junior high school brass band. The conclusion is that there is clinical usefulness for the evoked otoacoustic emissions in evaluating cochlear function and in predicting noise susceptibility.     

Evoked otoacoustic emissions in normal-hearing infants and children: emerging data and issues

Evoked otoacoustic emissions (EOAEs) are a promising tool for evaluating cochlear status in children. Preliminary data from normal-hearing subjects ranging from birth to 29.9 years old are discussed. EOAEs are present and robust in infant ears. However, there is a statistically significant decrease in EOAE amplitude for a fixed stimulus level with increasing age even in a carefully screened sample. At the present time it is unclear if these age-associated changes are due to normal developmental changes in the external and/or middle ear acoustics, normal developmental changes in cochlear mechanics and/or everyday cochlear wear and tear. Issues related to further application of evoked emissions to pediatric populations are discussed.     

新生儿自发性耳声发射与瞬态诱发性耳声发射的相关性

目的分析自发性耳声发射（spontaneous otoacoustic emission,SOAE）与瞬态诱发性耳声发射（transient evoked otoacoustic emission,TEOAE）之间的相关性。方法新生儿112例（224耳）,其中女59例,男53例,出生后2～4天内行SOAE及TEOAE检测。结果每耳SOAE信号峰数量与其TEOAE强度相关（r=0.43,P〈0.001）。每耳最大SOAE波幅与其TEOAE强度相关（r=0.49,P〈0.001）。不同耳依据其SOAE信号峰数量将其分为4组：I组无SOAE信号峰;II组为单SOAE信号峰;III组为2～3个SOAE信号峰;IV组为3个以上信号峰。I组TEOAE强度为（10.96±3.77）dBSPL,II组（12.87±3.27）dBSPL,III组（15.61±3.23）dBSPL,IV组（17.100±4.51）dBSPL,各组间的TEOAE强度差异均具有统计学意义。II组SOAE最大强度（-13.54±9.21）dBSPL,III组（-4.56±7.22）dBSPL,IV组（1.00±7.35）dBSPL,各组间最大SOAE波幅差异具有统计学意义。结论SOAE信号峰数量、最大SOAE波幅与TEOAE强度之间存在正相关关系,SOAE信号峰越多,最大SOAE波幅也越强,同时TEOAE强度也越强。     

Evoked otoacoustic emissions in normal and hearing impaired adults and children

In adults and children, 203 normal ears, 124 cars with hearing-impairment and 37 ears with middle ear problems were studied concerning click-evoked oto-acoustic emissions. According to the results, this method by high specifity and sensitivity renders possible the recognition of low sensory hearing losses. Complete middle ear effusions too make themselves conspicuous by preventing the reception of these responses. The recording of click-evoked oto-acoustic emissions is a most promising auditory screening-method. A general use could essentially improve the early detection of hearing losses in infants. Additionally, in the pedaudiologic practice possibilities are indicated to employ this technique as a topodiagnostic instrument.     

Evoked otoacoustic emissions in diagnosis of cochlear hearing disorders]

The authors consider the possibility of routine use of evoked otoacoustic emissions (EOE) in diagnosis of sensory hearing loss by comparison of EOE curves with relative curves obtained by pure tone audiometry. 180 ears with sensory hearing loss of different aetiologies were examined. EOE were obtained by application of Bray and Kemp's Evoked Otoacustic Measurement Package (ILO88). The results obtained show a close correlation between presence of EOE and real hearing losses of different frequencies obtained by pure tone audiometric evaluation. We could detect no EOE with hearing losses over 50 dB HL at 500 Hz, 40 dB HL at 1000 Hz, 50 dB HL at 2000 Hz and 85 dB HL at 4000 Hz. With a rate of middle hearing loss over 45 dB HL we also did not find EOE for the whole frequency range. On the base of this study, the authors conclude that EOE explore the functional integrity of those parts of the cochlea that correspond to the middle frequencies of hearing range. If EOE are not detectable, statements on the nature and extent of hearing loss on the base of this examination are not valid.     

Evoked otoacoustic emissions and their modification by contralateral acoustic stimulation]

The active vibration of the basilar membrane as well as evoked otoacoustic emissions (EOAE) are probably based on the motile properties of cochlear outer hair cells (OHC). In the present study we examined the effects of contralateral acoustic stimulation on ipsilateral EOAE and thereby the active cochlear micromechanics. Contralateral white noise with intensities below 30 dB HL enhanced the EOAE amplitude, whereas higher sound levels reduced the evoked acoustic emissions. Similar effects of contralateral acoustic stimuli on ipsilateral EOAE were observed in patients with a conductive hearing loss. However, the required sound levels were higher compared to probands with normal hearing. In controls with unilateral deaf patients white noise up to 60 dB HL did not alter the EOAE amplitude. We concluded, that in patients with normal hearing or unilateral conductive hearing loss, effects of contralateral acoustic stimulation on evoked ipsilateral sound emissions may be due to the activation of crossed olivo-cochlear efferents reaching the OHCs.     

Evoked otoacoustic emissions in a nonlinear model of the cochlea.

A nonlinear, transmission-line-analog model of the ear is presented for the purpose of simulating the experimental data of delayed evoked otoacoustic emissions (DEOAEs). The model produces echoes very similar to DEOAEs in the latency, saturation and spectral features when hypothetical, highly damped points arranged on the BM with an equal spacing are assumed. Special attention is payed to the reason for the long latency of DEOAEs. In the model, the delay occurs spuriously by cancellation of components scattered from the irregular points and is longer than the simple round trip time of the travelling wave from the stapes to the place of characteristic frequency. The echoes in the model are basically linear for the low intensity stimuli and only when the stimuli surpass a certain level they saturate owing to the nonlinearity of the BM damping.     

Evoked otoacoustic emissions and auditory brainstem responses: concordance in hearing screening among high-risk children

OBJECTIVE: Evoked otoacoustic emissions (OAEs) and diagnostic auditory brainstem responses (ABRs) were determined in 379 high-risk children referred for hearing screening. MATERIAL AND METHODS: This was a retrospective, cross-sectional study. The records of 379 children referred for hearing screening between January 2002 and March 2003 at the Ear Unit of the Philippine General Hospital were evaluated. RESULTS: Of the 379 children, 53.6% were male and 46.4% were female and the mean age was 41+/-47 months. The age distribution was as follows: < or = 12 months, 32.2%; 12-24 months, 52.2%; and > 24 months, 11%. Out of 229 right and 232 left ears, 111 (48.5%) and 112 (48.3%) had "pass" responses and 113 (49.3%) and 116 (50.5%) had "refer" responses, respectively. Five right and four left ears had "noise" responses. Out of 266 right and 209 left ears, the ABR results showed 72 (27.1%) and 30 (14.4%) with normal auditory pathways and 194 (72.9%) and 179 (85.6%) with abnormal auditory pathways, respectively. Of the 131 children whose parents gave their consent for concomitant OAE and ABR testing, agreements were observed between the two tests in terms of classifying the results as normal or abnormal of 78.9% (kappa = 0.51; p = 0.00) in right and 78.6% (kappa = 0.51; p = 0.00) in left ears. When the children were classified as either "with hearing loss-bilateral abnormal ABRs" or "at least one normal ABR", there was an observed agreement of 81% (kappa = 0.6; p = 0.00). OAEs had a sensitivity of 76.9% (95% CI 66.7-84.8%) and a specificity of 90% (95% CI 75.4-96.7%). CONCLUSION: There is good concordance between OAE and ABR results among high-risk children referred for hearing screening.     

Evoked otoacoustic emissions and auditory brainstem responses: concordance in hearing screening among high-risk children

Objective Evoked otoacoustic emissions (OAEs) and diagnostic auditory brainstem responses (ABRs) were determined in 379 high-risk children referred for hearing screening.

Material and Methods This was a retrospective, cross-sectional study. The records of 379 children referred for hearing screening between January 2002 and March 2003 at the Ear Unit of the Philippine General Hospital were evaluated.

Results Of the 379 children, 53.6% were male and 46.4% were female and the mean age was 41±47 months. The age distribution was as follows: ≤12 months, 32.2%; 12–24 months, 52.2%; and>24 months, 11%. Out of 229 right and 232 left ears, 111 (48.5%) and 112 (48.3%) had “pass” responses and 113 (49.3%) and 116 (50.5%) had “refer” responses, respectively. Five right and four left ears had “noise” responses. Out of 266 right and 209 left ears, the ABR results showed 72 (27.1%) and 30 (14.4%) with normal auditory pathways and 194 (72.9%) and 179 (85.6%) with abnormal auditory pathways, respectively. Of the 131 children whose parents gave their consent for concomitant OAE and ABR testing, agreements were observed between the two tests in terms of classifying the results as normal or abnormal of 78.9% (κ=0.51; p=0.00) in right and 78.6% (κ=0.51; p=0.00) in left ears. When the children were classified as either “with hearing loss—bilateral abnormal ABRs” or “at least one normal ABR”, there was an observed agreement of 81% (κ=0.6; p=0.00). OAEs had a sensitivity of 76.9% (95% CI 66.7–84.8%) and a specificity of 90% (95% CI 75.4–96.7%).

Conclusion There is good concordance between OAE and ABR results among high-risk children referred for hearing screening.