Spontaneous, click-, and toneburst-evoked otoacoustic emissions from normal ears

Evoked and spontaneous otoacoustic emissions were recorded bilaterally in a group of normal subjects (n = 14) using clicks and tonebursts at four frequencies (0.5, 1, 1.5, and 3 kHz). All ears (n = 28) demonstrated evoked emissions, but not to every stimulus type. The 0.5-kHz toneburst evoked emissions in only 10 (36%) ears, the 1.5-kHz toneburst in all ears, and the remaining stimuli in at least 80% of ears. Two distinct patterns of evoked emissions were identified. Five (18%) ears showed short, broadband click-evoked emissions lasting less than 20 ms after stimulus onset. In these ears, toneburst-evoked emissions were often more prominent than click-evoked emissions and no spontaneous emissions were detected. Twenty-three (82%) ears showed click-evoked emissions lasting longer than 20 ms poststimulus onset. Spectral analysis of these emissions demonstrated several (2-10) narrow frequency peaks. Highly similar peaks were present in the spectra of toneburst-evoked emissions within the range of toneburst spectra. Spontaneous emissions were recorded in 12 of the 23 ears. In these ears, at the frequencies of spontaneous emissions, prominent peaks in both click- and toneburst-evoked emission spectra were always present. Otoacoustic emission characteristics correlated significantly between the ears of individual subjects inferring that a symmetrical cochlear mechanism generates otoacoustic emissions.     

Nonlinear phenomena in click- and tone-burst-evoked otoacoustic emissions from human ears

Otoacoustic emissions have been recorded from normally hearing subjects in response to clicks and 1-kHz tone bursts. Input-output relationships for response magnitudes and wave delays are presented. For the response magnitudes, two main effects are seen: (i) nonlinearities are maximal at moderate to high intensity levels (saturation), while deviations from linearity are minimal at the lowest levels (around the psychoacoustic threshold); (ii) the nonlinear behaviour is different at different time intervals (after stimulation): deviations from linearity are maximal for the latest parts of the response. Level- and time-dependent phenomena are also observed in the delay of identifiable response waves.     

Transient-evoked otoacoustic emissions in a representative population sample aged 18 to 25 years

Transient-evoked otoacoustic emissions (TEOAEs) were obtained from 688 ears of a group of 345 young adults aged 18 to 25 years, using the Otodynamics ILO88 in the standard, non-linear mode. Normative data for TEOAEs obtained from 186 otologically normal (ON) ears are presented. In 5 ON ears, there was no recordable response, despite hearing threshold levels better than 20 dB. The main factors affecting the TEOAE level were (1) gender, where females had larger responses on average than males; (2) tympanometric measures, where ears with entirely normal tympanometric measures had larger responses than those with minor tympanometric abnormalities; (3) click stimulus intensity measured in the ear canal, which correlated positively with TEOAE level; and (4) hearing threshold level at 0.5 kHz, which correlated negatively with amplitude. There was also a small effect of social noise exposure in the 2-kHz region of the TEOAE, where the response was lower in those subjects exposed to significant social noise.     

Distortion product otoacoustic emissions in normal and hearing-impaired ears

Otoacoustic emissions of distortion products (DPOAE's) were recorded in normal and hearing-impaired human ears using relatively straightforward methods. Two pure-tone stimuli at fixed frequency levels of 73 dB HL for f1 and of 67 dB HL for f2 were used. The frequencies of the two primaries were chosen so that their geometric mean represented standard audiometric frequencies. Measurements of the emission amplitudes at 2f1-f2 and the adjacent noise floor were achieved by spectral averaging. A total of 101 subjects (199 ears) were tested. Seventy-seven ears in 46 subjects had normal hearing (hearing levels less than or equal to 20 dB at standard audiometric frequencies; average hearing levels, less than or equal to 10 dB). Thirty-six ears in 25 subjects had near-normal hearing (no hearing complaints, hearing levels less than or equal to 40 dB; average hearing levels, less than or equal to 20 dB). No significant differences in mean DPOAE values were apparent between these two groups of ears. All but two of these 113 ears (98%) showed emissions at three or more of the six frequencies tested between 1 and 6 kHz. Emissions were detected in more than 75% at each frequency between 1 and 6 kHz and in more than 85% between 1 and 4 kHz. A further 86 ears in 44 subjects exhibited varying degrees of sensorineural hearing loss caused by different pathologies. In general, emission amplitudes approximated the shapes of the audiograms, and a highly significant correlation between hearing thresholds and emission amplitudes was demonstrated in the frequency range of 1 to 4 kHz.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of ventilation tubes on otoacoustic emissions. A study of 106 ears in 62 children

The aim of this investigation was to study the presence and the characteristics of transient evoked otoacoustic emissions (TEOAE) in ears with ventilation tubes. Theoretically the small mass and the opening of the tube could influence the OAE. We studied a population of children between the age of 3 and 9 years with functional ventilation tubes and a normal hearing on pure tone audiometry (Fletcher index < 25 dB). A total of 110 ears from 62 children were included. According to the criterion of 70% wave reproducibility, TEOAE were present in 86.7% of the ears. Looking at the reproducibility in the different frequency bands of the response, it was found that the TEOAE were strongest in the 2 kHz frequency band. It is concluded that the measurement of TEOAE can be used as a useful hearing test in young children with ventilation tubes, maybe even when pure tone audiometry is not yet possible. However, false negative results were found in about one tenth of the ears.     

Distortion product otoacoustic emissions in normal and impaired adult ears

Distortion product otoacoustic emissions (DPOEs) were recorded in a group of normally hearing subjects (29 ears) and a group of subjects whose conditions were diagnosed as sensorineural hearing loss (23 ears) to study any correlation that might exist between DPOE characteristics and hearing impairment of different configurations. Three different DPOE paradigms have been used to investigate the influence of different test parameters on the DPOE data for normal and hearing-impaired ears. All normally hearing ears demonstrated detectable DPOEs, provided that the primary tone level was above a certain value. Hearing-impaired ears produced substantially reduced DPOEs compared with normally hearing subjects when the primary frequencies f1 and f2 corresponded to the region of hearing loss. Our data also suggested that, in general, more than one f2/f1 ratio is needed to examine any particular frequency region. The DPOEs provide frequency-specific information about cochlear function, which after further development, may form a basis for a noninvasive, objective method of evaluating cochlear function.     

Click- and tone-burst-evoked otoacoustic emissions in normally hearing ears and in ears with high-frequency sensorineural hearing loss

Summary Otoacoustic emissions (OAEs) evoked by clicks and tone bursts (TBs) were measured using a minor modification of the 1987 Bray and Kemp system in normal and hearing-impaired ears with high-frequency sensorineural hearing loss. Sixty ears of 60 subjects were tested. The average behavioral hearing threshold of 20 normally hearing ears was measured for the different nonlinear stimulus groups and defined as 0 dBnHL. Emissions were recorded in another 20 normally hearing ears and in 20 ears with steep high-frequency sensorineural hearing loss above 2 kHz. An unfiltered click of 80 s duration and TBs at frequencies of 0.5, 1, 2, 3, 4, 5, and 6 kHz served as stimuli. The ears with high-frequency hearing loss were clearly distinguished from the normal ears in that emission energy decreased with higher frequency stimuli above 2 kHz. The mean slopes of the response-growth functions were significantly higher at lower audiometric thresholds. The normal ears showed a slope of 0.21–0.35dB/dBnHL above 2kHz while the slope of the pathological ears was 0.04–0.13 dB/dBnHL. These differences in TBOAEs could possibly be used clinically to carry out hearing tests that are more frequency-specific than those measuring solely click-evoked OAEs. Pathological ears had emissions in the lower frequency range, where they had a normal audiometric threshold. However, these emissions had significantly far lower amplitudes at frequencies around 0.5 and 1 kHz when compared to normal ears. This reduced emission energy may indicate a cochlear impairment of the pathological ears in frequency ranges where they still had normal audiometric thresholds.Portions of this report were presented at the ADANO (Arbeitsgemeinschaft Deutscher Audiologen und Neurotologen) Meeting in Flims, Switzerland, March 29–31, 1990 Offprint requests to: R. Hauser     

Test-retest variability of distortion-product otoacoustic emissions in human ears with normal hearing.

In the present study, the test-retest variability of distortion product otoacoustic emissions (DPOAEs) due to various causes has been assessed quantitatively at individual frequencies using the ILO88/92 system. The short-term variance was generally lower than 3 dB2. Changing the position and the fit of the probe may affect the level of background noise in the ear canal, which interferes with the responses of the DPOAEs mainly at low frequencies and can also influence the interaction of the resonances of the outer ear and acoustic stimuli. The long-term variance was significantly greater than short-term variance, but did not differ significantly from variance of refitting the probe. The total DPOAE variance was small across all the frequencies above 1000 Hz except for a small peak in the 2500 Hz range. This may be related to the low response amplitudes in this region. The limitation of DPOAE detection at frequencies below 1000 Hz must lead to caution in the interpretation of results in this frequency range. The magnitude of the total variance was similar to that found in audiometric studies.     

Transient-evoked otoacoustic emissions in a group of professional singers who have normal pure-tone hearing thresholds

OBJECTIVES: The objective of this study was to determine whether transient-evoked otoacoustic emissions (TEOAEs) measured in a group of normal-hearing professional singers, who were frequently exposed to high-level sound during rehearsals and performances, differed from those measured in age- and gender-matched normal-hearing non-singers, who were at minimal risk of hearing loss resulting from excessive sound exposure or other risk factors. DESIGN: Twenty-three normal-hearing singers (NH-Ss), 23 normal-hearing controls (NH-Cs), and 9 hearing-impaired singers (HI-Ss) were included. Pure-tone audiometry confirmed normal-hearing thresholds (>or=15 dB HL) at 0.5, 1.0, 2.0, 3.0, 4.0, 6.0, and 8.0 kHz in NH-Ss and NH-Cs, and confirmed mild, high frequency, sensorineural hearing loss in HI-Ss (HI-Ss were included only to estimate sensitivity and specificity values for preliminary pass or fail criteria that could be used to help identify NH-Ss at risk for music-induced hearing loss). TEOAEs were measured twice in all ears. TEOAE signal to noise ratio (S/N) and reproducibility were examined for the whole wave response, and for frequency bands centered at 1.0, 1.4, 2.0, 2.8, and 4.0 kHz. RESULTS: Moderate to high correlations were found between test and retest TEOAE responses for the three groups. However, absolute test-retest differences revealed standard deviations that were two to three times larger than those reported previously, with the majority of the variability occurring for the 1.0 kHz band. As such, only the best TEOAE response (B-TEOAE) from the two measurements in each ear was used in further analyses, with data from the 1.0 kHz band excluded. With one exception, within-group comparisons of B-TEOAE S/N and reproducibility across ears and gender revealed no statistically significant differences for either NH-Ss or NH-Cs. The only significant within-group difference was between left and right ears of NH-C females for S/Ns measured in the 2.0 kHz band, where median responses from right ears were found to be higher than left ears. Across-group comparisons of B-TEOAEs revealed lower median S/N and reproducibility values for NH-Ss compared with NH-Cs for the whole wave response and 1.4 kHz band. For the 2.0 kHz band, reproducibility was similar for the normal-hearing groups but median S/N was found to be lower for NH-Ss. No significant differences in S/N or reproducibility were found between normal-hearing groups for the 2.8 and 4.0 kHz bands. Using data from NH-Cs and HI-Ss to establish sensitivity and specificity values for various TEOAE pass or fail criteria, six preliminary criteria were identified as having sensitivity and specificity values >or=90%. When these criteria were applied to NH-Ss, the number of NH-S ears passing ranged from 57% to 76%, depending on the criteria used to judge the NH-S ears, which translates into 24% to 43% of ears failing. CONCLUSIONS: Although TEOAE responses were measurable in all singers with normal audiometric thresholds, responses were less robust than those of NH-Cs. The findings suggest that subtle cochlear dysfunction can be detected with TEOAE measurement in a subset of normal-hearing professional singers. Although preliminary, the study findings highlight the importance of pass or fail criterion choice on the number of ears that will be identified as "at risk" for music-induced hearing loss.     

Spontaneous otoacoustic emissions: incidence and short-time variability in normal ears

More than 50% of normal ears generate spontaneous otoacoustic emissions, which are sinusoidal tones originating in the cochlea. These faint sounds with levels typically at 10 dB to -30 dB are usually not recognized by the subjects who have them, but can be recorded by sensitive microphones in the ear canal. The clinical significance of having or not having spontaneous emissions are at present unknown. The emissions may be useful for non-invasive monitoring of cochlear physiology. A total of 307 spontaneous otoacoustic emissions from 59 ears have been examined. The short-time variability was small when as many as 300 averages were collected. High-frequency emissions showed better stability than low-frequency ones. The ratio of frequency distance between neighboring emissions to critical bandwidth (Bark) was preferentially 0.3-0.5 for lower frequencies and 0.2-0.4 for the higher ones. Amplitude dependence for one emission on its neighbors was difficult to demonstrate. Combination tones (different tones f2-f1 and the cubic distortion product 2 x f1-f2) are probably rare among spontaneous emissions.     

Bacteriology of otorrhea from tympanostomy tubes

Culture results from 100 consecutive cases of otorrhea from tympanostomy tubes are presented. In children younger than 3 years, the culture results are very similar to those seen in patients with acute otitis media who do not have tubes. In children older than 3 years, the flora resembles that of external otitis. Suggestions for treatment are made.     

Circadian and menstrual rhythms in frequency variations of spontaneous otoacoustic emissions from human ears.

This paper reports hourly and daily monitoring of the frequencies of spontaneous otoacoustic emissions. Regular circadian variations in frequency were found in two of three subjects. Consistent monthly variations, in step with the menstrual cycle, were seen in three of four women. The circadian cycle typically showed a rise in frequency of 0.6-1% while asleep and a similar fall while awake. The monthly cycle typically saw frequencies rise and fall by 0.4-0.6%, reaching a minimum near the onset of menstruation, and rising to a peak close to ovulation. A review of the literature revealed that certain cardiovascular parameters such as arterial blood pressure follow, over both daily and menstrual cycles, a broadly similar time course to SOAE frequency. Further experiments produced data supporting a relationship between blood pressure and SOAE frequency, and it is therefore suggested that much of the circadian-linked, menstrual-linked, and background variation in SOAE frequency may arise from cardiovascular changes. A likely causal mechanism, involving cerebrospinal fluid, is discussed.     

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.     

分泌性中耳炎鼓膜切开置管术的并发症(附115耳分析)

目的:分析分泌性中耳炎鼓膜切开置管术后的并发症.方法:应用鼓膜切开置管术治疗分泌性中耳炎115耳,术后随访其并发症.结果:术后并发症的发生率依次为耳漏(10.1%),鼓室硬化症(8%),鼓膜穿孔(3.4%)、耳鸣(1.7%),感音神经性聋(0.8%).结论:应用小型鼓膜通气管可显著减少置管术后并发症发生率.     

Contralateral suppression of distortion product otoacoustic emissions and the middle-ear muscle reflex in human ears

Distortion product otoacoustic emissions (DPOAEs) were measured in the absence and presence of contralateral noise at five levels--below, equal to, and above the middle-ear muscle (MEM) reflex threshold. The resultant changes in DPOAE level and phase were dependent on stimulus frequency and noise level. Both low-level noise, believed to elicit the medial olivocochlear (MOC) reflex, and high-level noise, thought to activate both MOC and MEM reflexes, significantly decreased the DPOAE level. However, the shift from sole MOC effect to mixed MOC and MEM effects was not as dramatic as we thought. While low-level noise resulted in a minimum DPOAE phase change, high-level noise caused a substantial phase lead for 1 and 2kHz. With increasing frequency, phase lag became more notable. The present study suggests the following: (1) DPOAE contralateral suppression by low-level sound most likely does not involve the effect of the MEM reflex and signal crossover; and (2) combined analysis of DPOAE level and phase changes warrants further investigations to overcome the difficulty in separating the effects of MOC efferents and MEM contraction. The results also imply that OAE measurement has the potential for being used to investigate the effect of the MEM reflex on sound transmission.     

Water precautions in children with tympanostomy tubes.

PURPOSE: The necessity and effectiveness of taking precautions around water with children who have tympanostomy tubes is a source of some controversy among otolaryngologists. This study was undertaken to survey the practice standards of otolaryngologists treating these children. MATERIALS AND METHODS: A total of 1,266 board-certified otolaryngologists practicing (mean 14.8 years in practice) in the southern and eastern United States were surveyed to determine current recommendations. RESULTS: Among those surveyed, 13.1% forbid children with tympanostomy tubes from swimming, whereas 3.1% feel that no water precautions are needed. Limitations are placed in the depth of swimming by 68% and the type of swimming water by 18%. The most commonly recommended form of protection is the use of ear plugs, which is favored by 53.4%. Liberalization of recommendations concerning the need for water precautions was noted by 79% of respondents who cited personal experience as the single most influential factor. An overwhelming percentage of respondents indicated they would be willing to alter their current practice based on new information generated from a clinical trial. CONCLUSION: This survey demonstrates that diversity of opinion does exist among otolaryngologists relative to their recommendations for water precautions after placement of tympanostomy tubes. This survey demonstrates the need for a prospective randomized clinical trial designed to address this issue.