Growth of Evoked Otoacoustic Emissions during the First Days Postpartum: A Preliminary Report

Evoked otoacoustic emissions (EOAEs) were recorded twice in 20 ears of 15 newborns. The recordings were performed in a room of the well baby ward, using the ILO88 in its default setting, i.e. with click stimulation. On the first test occasion, the infants were between 3 and 51 h of age, and EOAEs were identified in 10 ears. On the second test occasion, while the infants were at least 1 day older (range 42–107 h), EOAEs were present in all ears. The second EOAE was stronger, so the EOAE appeared to grow in the first days postpartum. This might be due to middle ear clearance of amniotic fluid, shortly after birth. The results of the EOAEs of the second examination were compared with 10 EOAEs in adult ears. The response levels of the newborns were significantly higher than in the adults. The (cross-)correlation peak value of the two tests' waveforms is over 0.75, however sometimes only after filtering around the most pronounced emission frequencies. The study proves that newborns failing the EOAE screen in the first 24 h after birth can pass if retested 1 day later, simply because of growth of EOAE strength.     

婴幼儿单侧听神经瘤

目的：探讨婴幼儿单侧听神经病（AN）神经生理学特点。方法：对3例单侧AN患儿在采集病史和耳科检查的基础上,行系统的听力学检查,包括声阻抗、镫骨肌反射、听性脑干反应（ABR）、耳蜗微音电位（CM）、诱发耳声发射（EOAE）、中潜伏期反应（MLR）和事件相关电位（ERP）以及CT和（或）MRI及周围神经系统检查。结果：3例患儿鼓室图均呈“A”型,健耳的同侧和交叉镫骨肌反射可正常引出,而患耳的同侧和交叉镫骨肌反射未引出。3例患儿双侧EOAE有效引出,健耳的ABR正常引出,思耳的ABR未引出,但CM均正常。3例患儿双耳均记录到MLR及ERP。影像学和周围神经系统未见异常。结论：单侧AN与双侧AN有相似的神经生理学特点。对婴幼儿单侧AN的诊断应着重分析其神经生理学特点,建议联合应用EOAE、ABR、CM和影像学检查。应对AN患儿定期随访。     

Screening for auditory dysfunction in infants by evoked oto-acoustic emissions

Auditory threshold using auditory brain-stem responses (ABR) was determined in 30 ears from normally-hearing infants and 16 ears from infants with sensorineural deafness. In the same population, evoked oto-acoustic emissions (EOAEs) in response to a click of 20-dB hearing level were recorded. The presence of EOAEs was correlated with ABR thresholds. Evoked oto-acoustic emissions were always present when ABR wave V threshold was equal to or below 30-dB hearing level. On the contrary, infants with ABR thresholds higher than 40-dB hearing level never had EOAEs. As the recordings of EOAEs could be obtained more rapidly than ABR thresholds (average duration: five minutes vs 40 minutes), EOAEs could hold some promise as an objective, easy, and noninvasive test for screening auditory dysfunction in infants.     

The effect of stimulus level on click evoked oto-acoustic emissions and brainstem responses in neonates under intensive care

Click evoked oto-acoustic emissions (EOAE) at a range of stimulus levels and the auditory brainstem response (ABR) threshold have been measured in 40 infants admitted to a neonatal intensive care unit (NICU). The stimulus levels at which the emissions were first observed had a similar mean value and distribution to those found in previous studies on normal newborns and young adult volunteers. The difference was in the proportion who had no detectable emissions, 16.7% as against 3.9% in the normal newborns and 2.6% in young adult volunteers. The distribution of thresholds for the ABR was again similar to those measured on normal newborns but 8.1% of the ears of the NICU infants had a threshold worse than 53 dBnHL compared with 0% for the normal newborns. A combined screening method starting with the click evoked oto-acoustic emission is proposed. A comparison of the mean ABR thresholds for those in whom an EOAE was recorded to those with no EOAE showed a group effect. The stimulus latency relationship of the NV peak showed too much variation between individual results to consider its use to define accurately the degree of conductive hearing loss.     

A correlative study of evoked otoacoustic emission properties and audiometric thresholds

Summary Correlations were made between the detection thresholds of evoked otoacoustic emissions (EOAEs), subjective click thresholds, and mean audiometric thresholds in 240 normal and hearing-impaired ears. EOAEs have never been observed when subjective click thresholds or mean audiometric thresholds were equal to or greater than 35 dB HL. EOAEs were always found when click thresholds were equal to or lower than 15dB HL and when mean audiometric thresholds were equal to or lower than 22dB HL. The incidence of EOAEs decreased and EOAE thresholds increased with increasing click or mean audiometric thresholds.     

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.     

A correlative study of evoked otoacoustic emission properties and audiometric thresholds

Correlations were made between the detection thresholds of evoked otoacoustic emissions (EOAEs), subjective click thresholds, and mean audiometric thresholds in 240 normal and hearing-impaired ears. EOAEs have never been observed when subjective click thresholds or mean audiometric thresholds were equal to or greater than 35 dB HL. EOAEs were always found when click thresholds were equal to or lower than 15 dB HL and when mean audiometric thresholds were equal to or lower than 22 dB HL. The incidence of EOAEs decreased and EOAE thresholds increased with increasing click or mean audiometric thresholds.     

Paradoxical effects of contralateral white noise on evoked otoacoustic emissions in ears with acoustic neuroma

A contralateral suppression effect on evoked otoacoustic emissions (EOAEs) is usually present in normally hearing subjects and in patients with sensorineural hearing loss, while it is absent or reduced in ears to which the vestibular nerve has been cut and in ears with acoustic neuroma (AN). To date, a paradoxical effect, that is an increase in EOAE amplitude during contralateral stimulation, has been described in one ear with sensorineural hearing loss of unknown aetiology and in three ears with AN (two in the present paper). Evidence has been provided that the contralateral suppression effect on EOAEs is accomplished largely, if not entirely, via the medial olivocochlear bundle (OCB). According to clinical data the absence or the reduced amount of contralateral suppression effect on EAOEs may be attributed to a totally, or partially, damaged or malfunctioning medial OCB. The way in which a contralateral noise may increase EOAE amplitude is more difficult to explain. One attractive hypothesis is that this paradoxical effect is a result of some pathological adaptive process in the medial OCB.     

Paradoxical Effects of Contralateral White Noise on Evoked Otoacoustic Emissions in Ears with Acoustic Neuroma

A contralateral suppression effect on evoked otoacoustic emissions (EOAEs) is usually present in normally hearing subjects and in patients with sensorineural hearing loss, while it is absent or reduced in ears to which the vestibular nerve has been cut and in ears with acoustic neuroma (AN). To date, a paradoxical effect, that is an increase in EOAE amplitude during contralateral stimulation, has been described in one ear with sensorineural hearing loss of unknown aetiology and in three ears with AN (two in the present paper). Evidence has been provided that the contralateral suppression effect on EOAEs is accomplished largely, if not entirely, via the medial olivocochlear bundle (OCB). According to clinical data the absence or the reduced amount of contralateral suppression effect on EAOEs may be attributed to a totally, or partially, damaged or malfunctioning medial OCB. The way in which a contralateral noise may increase EOAE amplitude is more difficult to explain. One attractive hypothesis is that this paradoxical effect is a result of some pathological adaptive process in the medial OCB.     

Age-related changes in evoked otoacoustic emissions

Outer hair cells of the organ of Corti play an important part in the genesis of evoked otoacoustic emissions (EOAEs), which are related to cochlear biomechanics. The aim of this study was to investigate the age factor in relation to EOAEs in 166 ears of subjects between 6 weeks and 83 years of age. The results show that when age increases, the presence of EOAEs by age group and the frequency peak in spectral analysis decrease, and EOAE threshold increases. Thus, there is an effect of age upon EOAEs, and it seems linked with alteration of cochlear biomechanics and/or hair cell loss. Such an effect has to be taken into consideration when EOAEs are used in clinical applications, and limits the use of EOAEs in older subjects.     

Differential effects of ear-canal pressure and contralateral acoustic stimulation on evoked otoacoustic emissions in humans.

The effect of ear canal pressure variation (ECPV) on click evoked otoacoustic emissions (EOAEs) was compared to the suppressive effect observed with contralateral acoustic stimulation (CAS) in 11 healthy subjects. Both total EOAE amplitude and amplitude of 200 Hz frequency bands (22) were analyzed. Our results revealed that the ECPV as the CAS induced a decrease of the total EOAE amplitude; these two factors showed an additive effect when they are conjoint. The study of the EOAE frequency bands showed that the majority of them decreased under CAS and ECPV; however, a few bands are not affected. Moreover, it appeared that amplitude of the EOAE frequency bands were not modified in a similar way between the two factors: indeed some bands around 4.1 kHz did not decrease either by CAS or ECPV. These results suggest that these applied factors exert different actions on EOAEs. Moreover, the lack of a decrease effect for the same bands, both with CAS and ECPV, may explain the vulnerability of some cochlear locations.     

Evaluation of otoacoustic emissions in high-risk infants by using an easy and rapid objective auditory screening method

Summary Ninety-five ears of 53 infants at high risk for hearing impairment were examined using brainstemevoked response audiometry (BERA), stapedial reflex audiometry (SRA) and click-evoked otoacoustic emissions (EOAEs). By taking BERA as a reference, the results obtained were compared in order to evaluate the significance of EOAEs for auditory screening. EOAEs were present in more than 90% of the ears when the BERA threshold was below 30 dB. In this group of infants, the stapedial reflex was positive in about 80% of the ears examined. In contrast, EOAEs were never observed with BERA thresholds exceeding 40 dB. In several cases with BERA thresholds above 30 dB, elevated SRA values could also be recorded. A further advantage of EOAEs and SRA was a recording time of less than 3 min. Since the non-invasive recording of EOAEs was fast and easy to perform and the results obtained were reproducible, we conclude that click-evoked otoacoustic emissions are a reliable technique for demonstrating normal cochlear function.     

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.     

Activation of medial olivocochlear efferent system in humans: influence of stimulus bandwidth

The activity of the medial olivocochlear bundle (MOCB) can be studied in humans through variations in the level of evoked otoacoustic emissions (EOAEs) elicited by contralateral acoustic stimuli (CAS). The present study sought to investigate how the activity of the MOC system at a given frequency, as measured through the contralateral suppression of tone-pip EOAEs, depends on the bandwidth of the contralateral stimulus. EOAEs were recorded in 155 normal-hearing subjects, successively with and without contralateral stimuli whose bandwidth, center frequency and level were systematically varied. We showed a clear dependence of contralateral EOAE suppression on bandwidth demonstrating increased suppression with increased bandwidth over about two octaves around the center frequency of the noise. This effect was obtained irrespective of whether contralateral noise energy was kept constant independently of bandwidth or not, which indicates a role of bandwidth per se in contralateral EOAE suppression. Results are interpreted in terms of a simple model of MOCB activation mechanisms including peripheral bandpass filtering, within-channel compression and across-channel spatial summation by the afferent paths. Complementary experiments suggested a greater effectiveness of increases in bandwidth on the upper than on the lower side and of frequency components akin to or remote from the test frequency than of intermediate bands. Finally, these results were complemented by detailed spectrum analyses of the EOAE level variations induced by the different noises, which revealed that whilst noise components close to or remote from the center frequency generally attenuated EOAE level, intermediate components could in some cases lead to a relative increase in EOAE level. These results can further be explained by assuming different positive and negative weights on the inputs to the spatial summation process depending on their position relative to the center frequency.     

Middle-ear influence on otoacoustic emissions. II: contributions of posture and intracranial pressure

Although it seems likely that body tilt or surgically provoked variations in intracranial pressure (ICP) can result in variations of intralabyrinthine pressure, the channels for pressure transmission remain controversial and the reasons why evoked otoacoustic emissions (EOAEs) exhibit attendant modifications are unclear. The theoretical framework implemented in the companion paper [Avan et al. part I, 2000] provides sensitive and non-invasive means to identify the middle-ear mechanism(s) entailed in EOAE changes. It was thus applied to analyze the influence of posture on EOAE phases and magnitudes as a function of frequency, in a series of experiments involving body tilt from sitting to supine (0° or −30°). Controlled ICP variations were surgically carried out in a series of hydrocephalic patients and the resulting EOAE changes were compared to posture data and model predictions. In all cases, the EOAE changes closely resembled those due to an increase in the stiffness of the stapes’ annular ligament, in keeping with the assumption that ICP gets transmitted to intralabyrinthine spaces and modifies the hydrostatic load on the stapes, thereby influencing EOAE features. A small additional contribution of middle-ear pressure to EOAE changes was identified in addition to the main stapes component. Dynamical EOAE measurements showed that sudden ICP changes were transmitted to the inner ear within 8–30 s. The high sensitivity of EOAE phases below 2 kHz to ICP changes, together with the absence of any significant confounding middle-ear effect, favors EOAEs for a reliable non-invasive monitoring of ICP and intralabyrinthine pressures.     

天津市新生儿听力筛查及信息化建设

目的通过对新生儿听力筛查及信息化管理,早期发现和诊断先天性听力损失,及时干预。方法新生儿出生3～5d采用畸变产物耳声发射(distoetion product otoacoustic emissions,DPOAE)进行初筛;42d用DPOAE和自动判别听性脑干反应(auto auditory brainstem response,AABR)进行复筛;3个月和6个月分别用听性脑干反应(auditory brainstem responses,ABR)、多频稳态反应(auditory steady state response,ASSR)和声导抗检查进行两次诊断;有听力障碍的患儿适时干预措施,并定期复查和随访。结果 2009～2010年在天津市出生活产婴儿106547人,104224例生后3d开始进行听力测试,全市建立了新生儿听力筛查信息化网络管理。初筛率为97.82%;初筛时正常新生儿未通过率为9.12%(9075/99484),高危儿为23.65%(1121/4740),高危儿未通过率明显高于正常新生儿(χ2=1.082,P<0.01);42d复筛率为53.44%;3个月接受第一次诊断的有362例;6个月接受诊断的有117例,其中100例(161耳)有不同程度听力损失,中重度和极重度听力障碍患儿在6个月确诊后进行干预。结论①通过建立新生儿听力筛查信息网络化管理系统,初筛率达97%以上;②42d新生儿听力复筛采用DPOAE和AABR检测技术联合应用,减少了漏筛和漏诊;③高危新生儿初筛阳性率为23.65%,明显高于正常新生儿。     

Evoked oto-acoustic emissions from adults and infants: clinical applications

Evoked oto-acoustic emissions (EOAEs), i.e. sounds emitted by the cochlea in response to a click, are recordable in the ear canal by a miniature microphone. They reflect an active cochlear biomechanism based upon OHC function, which accounts for the exquisite properties of sensitivity and frequency selectivity of the cochlea. EOAE recordings can therefore be considered an objective, easy, rapid and non-invasive audiological procedure which can be used to investigate the most sensitive part of the cochlea. From our experience of more than 300 recordings, we propose several clinical applications of EOAEs: 1) objective assessment of sensorineural hearing loss; 2) staging Meniere's disease by recording glycerol-induced changes; 3) diagnosis of retrocochlear pathology, and 4) screening of auditory function 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.     

Click-evoked otoacoustic emissions (CEOAEs) recorded from neonates under 13 hours old using conventional and maximum length sequence (MLS) stimulation

Maximum length sequence (MLS) stimulation allows click evoked otoacoustic emissions (CEOAEs) to be averaged at very high stimulation rates. This enables a faster reduction of noise contamination of the response, and has been shown to improve the signal-to-noise ratio (SNR) of CEOAEs recorded from adult subjects. This study set out to investigate whether MLS averaging can enhance the SNR of CEOAEs recorded in newborns within the first day after birth, and so improve the pass rates for OAE screening in this period, when false alarm rates are very high. CEOAEs were recorded in a neonatal ward from 57 ears in 37 newborns ranging from 6 to 13h old, using both conventional (50/s) and high rate (5000/s) MLS averaging. SNR values and pass rates were compared for responses obtained within equal recording times at both rates. MLS averaging produced an SNR improvement of up to 3.8dB, with the greatest improvement found in higher frequency bands. This SNR advantage resulted in pass rate improvement between 5% and 10%, depending on pass criterion. A significant effect of age was found on both SNR and pass rate, with newborns between 6 and 10h old showing significantly lower values than those tested between 10 and 13h after birth, as well as a much greater improvement due to MLS averaging. The findings show that MLS averaging can reduce false alarm rates by up to 15% in very young neonates in a neonatal ward setting.     

Evoked otoacoustic emissions: correlates between spectrum analysis and audiogram

Correlations between spectrum analysis of evoked otoacoustic emissions (EOAEs) and hearing losses have been calculated in 150 patients with pure sensorineural hearing loss. Significant correlations were found. The greater the high-frequency spectral components of the EOAE, the better the high-frequency hearing. However the relationship is complex, and it does not seem possible to establish an audiogram knowing only the spectrum analysis of EOAEs.