Characteristics of normal newborn transient-evoked otoacoustic emissions: ear asymmetries and sex effects

Transient-evoked otoacoustic emissions (TEOAEs) were recorded from more than 30000 newborns over a six year period. Analysis was performed on all the TEOAEs that passed the bedside universal hearing screen (n=60431), in order to characterize the normal properties of neonatal TEOAEs and to study ear and sex effects. Short recording times (median=33 s) were observed in combination with high entire TEOAE level (median=18.8 dB SPL for an 81.8 dB SPL peak stimulus), and high reproducibility (median=86%). Signal-to-noise ratio (S/N) of the TEOAE was highly frequency-dependent, being poorer at low frequencies. Prolonged averaging increased median reproducibility to 97%, but the minor S/N-improvement at low frequencies did not justify the longer test time. Highly significant mean lateral asymmetries (right >left) and sex differences (female >male) existed in entire TEOAE level, S/N TEOAE, and in half-octave frequency bands (700-4000 Hz). Mean lateral and sex entire TEOAE level differences were 1.1 dB and 1.3 dB, respectively. Stimulus levels were not affected by ear or sex. Hence, physiological differences at the level of organ of Corti were demonstrated in newborns.     

Contralateral suppression of otoacoustic emissions in neonates

The effect of contralateral acoustic stimulation on transient evoked otoacoustic emissions (TEOAEs) was used to investigate the activity of the medial olivocochlear bundle in neonates. TEOAEs were bilaterally recorded, with and without contralateral noise, in 120 full-term neonates without risk for hearing loss. Otoacoustic emission recordings were carried out using the Otodynamic ILO88 system quickscreener non-linear mode, and the contralateral stimulation was presented at 60 dB SPL delivered by CD player. The results revealed a significant (p<0.01) contralateral suppression of TEOAE response amplitude: 2.32 dB in females and 3.28 dB in males. This study shows that the suppression effect is present in 88.5% of neonates, with a gender difference (greater suppression in males) and frequency effect, suggesting a functional maturation of the medial olivocochlear bundle in the studied population.     

Spontaneous otoacoustic emissions in neonates and effect of contralateral white noise stimulation

Neonates younger than the age of 12 weeks (10 full-term, 20 preterm) had an audiological assessment consisting of brainstem audiometry, tympanometry, transiently evoked otoacoustic emissions, and spontaneous otoacoustic emissions with contralateral white noise stimulation. Results from brainstem audiometry, tympanometry, and transiently evoked otoacoustic emissions suggested normal middle ear function and normal cochlear function. All full-term neonates had multiple spontaneous otoacoustic emissions, and contralateral white noise stimulation resulted in enhancement of emissions in 80%, whereas in 20% the emissions were suppressed. In preterm neonates, spontaneous otoacoustic emissions were present in 55%. These emissions were mostly solitary and, in 64%, showed suppression with contralateral white noise stimulation. Embryological data taken into consideration suggest that the pattern of spontaneous otoacoustic emissions in preterm neonates is more likely related to immaturity of the central auditory pathway rather than the cochlea.     

Efferent inhibition of otoacoustic emissions in preterm neonates

IntroductionAbnormalities in auditory function of newborns may occur not only because of preterm birth, but also from the use of medications and from diseases related to prematurity.ObjectiveTo analyze the inhibitory effect from stimulation of the olivocochlear efferent system on transient evoked otoacoustic emissions in preterm neonates, comparing these data with those from full-term neonates.MethodsThis was a prospective, cross-sectional, contemporary cohort study with 125 neonates, pooled into two groups: full-term (72 full-term neonates, 36 females and 36 males, born at 37–41 weeks of gestational age); and preterm (53 neonates, 28 males and 25 females, born at ≤36 weeks of gestational age, evaluated at the corrected gestational age of 37–41 weeks). Otoacoustic emissions were recorded using linear and nonlinear click-evoked stimuli, with and without contralateral stimulation.ResultsThe inhibitory effect of the efferent pathway in otoacoustic emissions was different (p = 0.012) between groups, and a mean reduction of 1.48 dB SPL in full-term births and of 1.02 dB SPL in preterm births was observed for the non-linear click-evoked stimulus.ConclusionThe results suggest a reduced inhibitory effect of the olivocochlear efferent system on otoacoustic emissions in preterm neonates.     

Spontaneous and evoked otoacoustic emissions in preterm neonates.

Spontaneous (SOEs) and evoked otoacoustic emissions (EOEs) were recorded in a group of preterm neonates (N = 134 ears) in order to study the basic properties of SOEs and EOEs as a function of gestational age. In the study, it was found that: 1. EOEs were recorded in 93% of the tested ears; 2. SOEs were recorded in 61% of the tested ears; 3. there were no statistically significant variations of EOE amplitude with gestational age; 4. EOE spectrum did not vary with age; and 5. the two main factors influencing EOE amplitude were the SOE presence and the fast Fourier transform spectrum, especially the lower limit of the spectrum. Thus, the maturation of outer hair cell properties appears to be complete at 32 weeks of gestational age. Because a number of infants at risk for hearing loss are preterm babies, screening for EOEs, an objective, rapid, and nontraumatic technique, may prove useful in evaluating peripheral auditory dysfunction in preterm neonates.     

Analysis of otoacoustic emissions in neonates at term and preterm

The transient evoked otoacoustic emissions (TEOAEs) have been widely used in neonatal hearing screening.ObjectiveTo compare the TEOAEs in newborns at term and preterm vis-à-vis the following variables: ear side, gender, frequency spectrum and gestational age.MethodBy means of a cross-sectional cohort of 66 newborns up to the 28^th day of life (41 newborns at term and 25 premature babies), we recorded TEOAEs. All the individuals did not have risk indicators for hearing loss.ResultsThere was a signal/noise ratio improvement with frequency increase. No differences were observed between genders and between the ears, but there were differences among the children born at term and preterm in the frequency bands at 3 kHz and 4 kHz.ConclusionThe TEOAEs test is important for assessing the peripheral auditory system of newborns at term and preterm, making it possible to have responses regardless of gender and gestational age.     

Distortion-product otoacoustic emissions in neonates: normative data.

Distortion-product otoacoustic emissions (DPOEs) are otoacoustic emissions evoked by two pure tones and used in order to provide a frequency specific assessment of the mechanical properties of the cochlea. This paper first reports complete input-output DPOE functions for audiometric frequencies between 867 Hertz and 8 kHz in a normal neonate population (normative data). DPOE results were analyzed as a function of evoked otoacoustic emission (EOE) properties. Neonates having normal EOEs have large DPOEs. DPOE amplitudes in neonates are larger than in adults. Neonates with atypical EOE frequency spectrum without low frequency components had normal DPOE input-output functions only for high frequencies (above 2 kHz). DPOEs could be useful, in association with EOEs, to precisely evaluate the auditory peripheral function in neonates.     

Distortion-product otoacoustic emissions and glycerol testing in endolymphatic hydrops

OBJECTIVES/HYPOTHESIS: Aural fullness is a frequent symptom of endolymphatic hydrops. Its evaluation may provide valuable information on the initial stage of development of endolymphatic hydrops. STUDY DESIGN: The present investigation was specifically designed to ascertain the ability of the glycerol test, combined with pure tone audiometry and distortion product otoacoustic emissions (DPOAEs) testing, to diagnose endolymphatic hydrops early and to identify patients who may evolve toward Meniere's disease. For these purposes, patients who complained about aural fullness as their only audiologic symptom were selected. METHODS: This investigation consisted of 19 consecutive patients with unilateral or bilateral aural fullness who received no treatment. Each patient underwent glycerol testing measured with conventional pure tone audiometry and with both DPOAEs. For the traditional pure-tone glycerol test, a hearing improvement of at least 10 dB, at the lower two or three frequencies (125, 250, and 500 Hz), was judged as a positive result. For the DPOAE glycerol test, a smaller positive difference (5 dB) for at least three frequencies was interpreted as an ameliorative fluctuation. RESULTS: The outcomes of the glycerol tests (24 ears examined) showed variable patterns. Seven ears showed no significant changes of either the pure-tone audiogram or DPOAE. In seven other ears, the comparison of the traditional glycerol test and the DPOAE glycerol test indicated an improvement in both measures. Another seven ears showed negative glycerol tests, whereas DPOAE responses gradually recovered reaching levels significantly higher than those recorded before glycerol administration. The three remaining ears showed contrasting results. CONCLUSIONS: Patients with aural fullness in the absence of other associated symptoms may potentially be in the initial stages of Meniere's disease. This notion is confirmed by the present findings showing a high rate (58%) of positive glycerol tests in the selected patients. The importance of DPOAE testing is supported by their ability to detect minimal dysfunction, possibly representing endolymphatic hydrops that goes undetected by routine pure-tone audiometry.     

足月新生儿的瞬态诱发性耳声发射与听性脑干反应分析

本研究通过对听功能正常 2 2例 (42耳 )和异常 5 5例 (110耳 )的足月新生儿 TEOAEs和 ABR检测 ,将两种方法的主要参量进行对比分析和验证 ,发现 :1以 ABRs阈值≥ 40 d Bn HL为新生儿听损伤标准 ,TEOAEs四项参量指标和四项参量综合指标均为有效指标 ,其符合率如下 :TEOAEs反应强度为 98.6 8% ;TEOAEs反应波的重复率为96 .71% ;TEOAEs反应波 1～ 4k Hz频率范围 (1.0、1.5、2 .0、3.0、4.0 k Hz)的重复率为 96 .71% ;1～ 4k Hz频率范围(1.0、1.5、2 .0、3.0、4.0 k Hz) TEOAEs反应波的信噪比为 98.6 8% ;四项参量综合指标为 97.37% ;2听觉功能异常的足月新生儿中单侧耳听力受损伤 (5 8.18% )多于双侧耳 (41.82 % ) ;3TEOAEs测试结果存在假阴性率为 1.32 % ,假阳性率为 1.32 %。     

Spontaneous otoacoustic emissions in preterm neonates: prevalence and gender effects

A number of lines of evidence indicate that the human cochlea is fully functional as a mature sound transducer by 6 months of age. However, information about the development of the active cochlear mechanisms and notably the development of outer hair cell (OHC) activity is yet incomplete. Recording and analysis of otoacoustic emissions (OAEs), probably generated by the OCHs of the organ of Corti, have led to a better understanding, in humans, of how sounds are analysed in the cochlea by means of active mechanisms. Evoked OAEs (EOAEs) and spontaneous OAEs (SOAEs), when they can be recorded in full-term and preterm neonates, show different characteristics from those in adults, suggesting that maturation of the peripheral auditory system is incomplete at birth. To learn more about this maturation, using the best-established facts concerning SOAEs in adults, such as their greater prevalence in females and also in right ears, SOAEs were studied in more detail in 81 preterm neonates, from 30 to 40 weeks of conceptional age, all presenting bilateral EOAEs according to objective criteria.

The first finding of this study was that SOAEs existed and could be recorded as of 30 weeks of conceptional age in humans. Some SOAE characteristics in preterm neonates, such as prevalence, peak number and acoustic frequencies, showed similarity with full-term neonates. Comparison of other criteria between the two populations, such as greater SOAE prevalence in right ears and higher SOAE peak number in females, suggested that these developmental factors emerge around term in humans. Comparison of SOAE characteristics between male and female preterms suggested that male preterms were less advanced in peripheral auditory development than were female preterms.     

The characteristic of otoacoustic emissions in full-term neonates according to ABO blood groups

IntroductionPrevious research has suggested that individuals with different blood groups show varied incidences of noise-induced hearing loss. The reduced otoacoustic emissions amplitudes indicate the higher possibilities of outer hair cell damage for noise exposure.ObjectiveThe objective is to analyze the characteristics of otoacoustic emissions, including the occurrence of spontaneous otoacoustic emission and the amplitudes of distortion product otoacoustic emission at certain frequencies in full term neonates with different ABO blood groups.MethodsA total of 80 selected full-term female neonates who passed the initial newborn hearing screen were enrolled into the study, with equal number of participants in four ABO blood groups (Blood Group A, Blood Group B, Blood Group AB, Blood Group O). Measurements of spontaneous otoacoustic emission and distortion product otoacoustic emission were performed in both ears for all participants.Results(1) The blood group O participants showed significantly fewer spontaneous otoacoustic emission occurrences than the other three blood groups (A = 70%, B = 80%, AB = 67%, O = 25%, p <  0.05). (2) The blood group O participants showed lower DPOAE amplitudes at 1257 Hz (M = 4.55 dB, SD = 8.36), 1587 Hz (M = 11.60 dB, SD = 6.57), 3174 Hz (M = 7.25 dB, SD = 5.99), 5042 Hz (M = 13.60, SD = 6.70) than participants with the other three blood groups in left ears (p < 0.05). In right ears, the blood group O participants showed reduced amplitudes at 1257 Hz (M = 6.55 dB, SD = 8.36), 1587 Hz (M = 13.60 dB, SD = 6.57), 3174 Hz (M = 7.65 dB, SD = 6.43), 5042 Hz (M = 13.65 dB, SD = 6.50) than participants from non-O blood groups (p < 0.05).ConclusionFemale individuals with blood group O have lower otoacoustic emissions values than individuals with the other three blood groups. We need to further investigate the possible relationships between ABO blood group and cochlear function, including the potential influences of noise damage on cochlear outer hair cells.     

Transient evoked otoacoustic emissions in patients with middle ear disorders

The aim of this study is to investigate the middle ear dynamic characteristics and their influence on TEOAEs in patients with middle ear disorders. The middle ear dynamic characteristics and TEOAE findings were investigated in 89 patients with middle ear disorders using the sweep frequency impedance (SFI) meter and the ILO88 system, respectively. These patients were divided into six subcategories: tympanic membrane aberrations, otitis media with effusion, chronic otitis media, tympanic membrane perforation, otosclerosis, and ossicular chain dislocation. Details of the TEOAE frequency characteristics were compared with the individual's middle ear dynamic characteristics. TEOAE status as a function of hearing threshold and middle ear dynamic characteristics was also examined. The results showed that the middle ear dynamic characteristics in patients with middle ear disorders correlated with the TEOAE frequency characteristics and amplitudes. The hearing level and middle ear mobility were the controlling factors affecting TEOAE status. Using both non-linear and linear stimulus modes, larger TEOAE responses were obtained when the hearing level was better than 20 dB HL, and there was moderately good middle ear mobility. Moreover, TEOAEs were absent using the non-linear mode when the hearing level was worse than 30 dB HL, whereas with the linear mode. TEOAEs were recordable even with hearing losses of up to 40 dB HL in patients with middle ear disorders. A higher incidence of recordable TEOAEs was found in the subgroups with tympanic membrane abnormalities and secretory otitis media when compared with the other subgroups. No TEOAEs were recordable in patients with chronic otitis media.     

Audiometric predictions using stimulus-frequency otoacoustic emissions and middle ear measurements

OBJECTIVE: The goals of the study are to determine how well stimulus-frequency otoacoustic emissions (SFOAEs) identify hearing loss, classify hearing loss as mild or moderate-severe, and correlate with pure-tone thresholds in a population of adults with normal middle ear function. Other goals are to determine if middle ear function as assessed by wideband acoustic transfer function (ATF) measurements in the ear canal account for the variability in normal thresholds, and if the inclusion of ATFs improves the ability of SFOAEs to identify hearing loss and predict pure-tone thresholds. DESIGN: The total suppressed SFOAE signal and its corresponding noise were recorded in 85 ears (22 normal ears and 63 ears with sensorineural hearing loss) at octave frequencies from 0.5 to 8 kHz, using a nonlinear residual method. SFOAEs were recorded a second time in three impaired ears to assess repeatability. Ambient-pressure ATFs were obtained in all but one of these 85 ears and were also obtained from an additional 31 normal-hearing subjects in whom SFOAE data were not obtained. Pure-tone air and bone conduction thresholds and 226-Hz tympanograms were obtained on all subjects. Normal tympanometry and the absence of air-bone gaps were used to screen subjects for normal middle ear function. Clinical decision theory was used to assess the performance of SFOAE and ATF predictors in classifying ears as normal or impaired, and linear regression analysis was used to test the ability of SFOAE and ATF variables to predict the air conduction audiogram. RESULTS: The ability of SFOAEs to classify ears as normal or hearing impaired was significant at all test frequencies. The ability of SFOAEs to classify impaired ears as either mild or moderate-severe was significant at test frequencies from 0.5 to 4 kHz. SFOAEs were present in cases of severe hearing loss. SFOAEs were also significantly correlated with air conduction thresholds from 0.5 to 8 kHz. The best performance occurred with the use of the SFOAE signal-to-noise ratio as the predictor, and the overall best performance was at 2 kHz. The SFOAE signal-to-noise measures were repeatable to within 3.5 dB in impaired ears. The ATF measures explained up to 25% of the variance in the normal audiogram; however, ATF measures did not improve SFOAEs predictors of hearing loss except at 4 kHz. CONCLUSIONS: In common with other OAE types, SFOAEs are capable of identifying the presence of hearing loss. In particular, SFOAEs performed better than distortion-product and click-evoked OAEs in predicting auditory status at 0.5 kHz; SFOAE performance was similar to that of other OAE types at higher frequencies except for a slight performance reduction at 4 kHz. Because SFOAEs were detected in ears with mild to severe cases of hearing loss, they may also provide an estimate of the classification of hearing loss. Although SFOAEs were significantly correlated with hearing threshold, they do not appear to have clinical utility in predicting a specific behavioral threshold. Information on middle ear status as assessed by ATF measures offered minimal improvement in SFOAE predictions of auditory status in a population of normal and impaired ears with normal middle ear function. However, ATF variables did explain a significant fraction of the variability in the audiograms of normal ears, suggesting that audiometric thresholds in normal ears are partially constrained by middle ear function as assessed by ATF tests.     

Optimal band pass filtering of transient evoked otoacoustic emissions in neonates

This paper investigated the performance of an optimal bandpass filtering technique to effectively identify click evoked otoacoustic emissions in neonates. The frequency response of the filter was optimized by maximizing the correlation coefficient between two replicate recordings (reproducibility). The optimal cut-off frequencies were also set by controlling the maximum energy loss after filtering to stop the crucial response contents being filtered along with the noise. As an additional constraint, the cut-off frequencies were forced to be outside the range of 1.6 to 4.2 kHz to avoid (in a response identification task) the spontaneous otoacoustic emissions from polarizing the cut-offs and thereby filtering fundamental frequency components, thus leading to an erroneous response classification. The best performance of the optimal filter in terms of increasing the post-filtering reproducibility was obtained when the procedure was applied to recordings whose reproducibility before filtering ranged between 60 and 80 per cent, i.e. for responses classified in most cases as partial pass.     

Maternal smoking during pregnancy: impact on otoacoustic emissions in neonates

Objectives

To determine the effect of maternal smoking during pregnancy on transient evoked otoacoustic emissions levels in neonates.

Methods

This was a cross-sectional study investigating neonates in the maternity ward of a university hospital in the city of São Paulo, Brazil.A total of 418 term neonates without prenatal or perinatal complications were evaluated. The neonates were divided into two groups: a study group, which comprised 98 neonates born to mothers who had smoked during pregnancy; and a control group, which comprised 320 neonates born to mothers who had not.In order to compare the two ears and the two groups in terms of the mean overall response and the mean transient evoked otoacoustic emissions in response to acoustic stimuli delivered at different frequencies, we used analysis of variance with repeated measures.

Results

The mean overall response and the mean frequency-specific response levels were lower in the neonates in the study group (p < 0.001). The mean difference between the groups was 2.47 dB sound pressure level (95% confidence interval: 1.47-3.48).

Conclusions

Maternal smoking during pregnancy had a negative effect on cochlear function, as determined by otoacoustic emissions testing. Therefore, pregnant women should be warned of this additional hazard of smoking. It is important that smoking control be viewed as a public health priority and that strategies for treating tobacco dependence be devised.