SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Eight patients suffered sudden sensory neural hearing losses associated with exertion or trauma; all were found at tympanotomy to have round window membrane ruptures with leakage of perilymph. Operative findings, with audiometric, radiological and electrocohleographic results are shown. The aetiology is discussed, with particular reference to diving techniques and to the cochlear aqueduct.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The corticofugal (descending) auditory system forms multiple feedback loops, and adjusts and improves auditory signal processing in the subcortical auditory nuclei. However, the mechanism by which the corticofugal system modulates cochlear hair cells has been unexplored. We found that electric stimulation of cortical neurons via the corticofugal system modulates cochlear hair cells in a highly specific way according to the relationship in terms of best frequency between cortical neurons and hair cells. Such frequency-specific effects can be explained by selective corticofugal modulation of individual olivocochlear efferent fibers.
The acoustic reflex is considered to reduce transmission across the middle ear and thereby protect the inner ear from intense sounds. The dynamic properties of this reflex seem to be a function of the duration of the eliciting stimulus. Assessment of the protective action afforded by middle-ear muscle contractions for long-term noise exposures requires the knowledge of how these dynamic properties change under such conditions. Round window electrodes were implanted in eight chinchillas. Changes in the threshold of the acoustic reflex were measured during an eight-hour exposure at 95 dB SPL to an octave-band noise centered at 0.5 kHz. The criterion measure of the acoustic reflex was a change in the amplitude of the cochlear microphonic generated by a 0.5 kHz eliciting tone. Thresholds of the acoustic reflex increased systematically throughout the noise exposure up to approximately 14 dB after 8 hours. The time course of the changes in the threshold of the acoustic reflex was nearly identical to the time course of behaviorally measured changes in the auditory sensitivity as reported by Carder and Miller (1972).
The purpose of this investigation was to study the reliability of spontaneous otoacoustic emission (SOAE) suppression tuning curve (STC) measurements. Two repetitions of an SOAE STC, using a 4-dB suppression criterion, were obtained from 5 subjects who exhibited stable SOAE level (SD less than or equal to 1.5 dB) and SOAE frequency (+/- 5 Hz). Analyses of variance revealed no significant difference between the SOAE STC trials (p greater than .05). The SOAE frequency was below the SOAE STC tip, which is similar to the relationship between the probe frequency and a simultaneously masked psychophysical tuning curve. The mean slope of the SOAE STC low-frequency segment was 53.7 dB/octave, whereas the mean slope of the SOAE STC high-frequency segment was 124.8 dB/octave. The mean low- to high-frequency slope ratio was 2.4. The mean Q10 value for the 5 subjects was 5.3. The SOAE STC low- and high-frequency slopes and Q10 were similar to psychophysical tuning curve data obtained in simultaneous masking and physiological tuning curve data.
Explore the source record for details and available documents.
BACKGROUND: The necessity of screening examinations in newborns today cannot be denied. Up to now, it has only been achieved in a few countries to introduce a general hearing screening for newborns. METHODS: We examined 100 newborns (200 ears) at their third day of life. All ears were evaluated with the TEOAE-screening-device ECHOSCREEN. In addition, we carried out BERA screening examinations with the ALGO PORTABLE or with the EVOFLASH on 100 of these 200 ears. As a reference method, we utilized TEOAE-examinations with the ILO-88 for all ears. RESULTS: 4.5% of the 200 ears examined with the ECHOSCREEN were conspicuous due to accumulation of earwax problems. With the ALGO-system, none of the ears was conspicuous. Among the 100 ears examined with the EVOFLASH we found negative results with seven ears (4 children). These findings will be discussed in detail. Furthermore, we analyzed the costs for one-step- and two-step-screenings. Costs for a one-step-screening of both ears would be DM 14.27 with Echoscreen, DM 44.69 with ALGO, DM 32.19 with Evoflash for one patient including material and personnel costs. Costs for a two-step-screening would be DM 16.28 with Echoscreen and ALGO, DM 15.72 with Echoscreen and Evoflash, calculated per child on the basis of 812,173 newborn children in the year 1997 in Germany. CONCLUSION: On the basis of all these results, we recommend a two-step-screening with TEOAE and BERA-devices.
Explore the source record for details and available documents.
Contralateral white noise alters the amplitude of transitory evoked otoacoustic emissions (TEOAE). 27 students between 20 and 28 years of age with no history of ear disease or dizziness were tested for normal hearing by pure tone audiogram. OAE evoked by nonlinear stimuli were measured with and without contralateral stimulation by 40, 50 and 60 dB white noise. The contralateral stimulation resulted in a statistically significant diminution of the amplitude of the TEOAE under contralateral acoustic stimulation. This diminution is probably caused by the effect of the crossed bundle of the efferent innervation on the outer hair cells resulting in altered vibratory properties of the basilar membrane. In patients with unilateral acoustic neuroma and measurable TEOAE a diminution of the amplitude of the TEOAE under contralateral sound stimulation was not found. The testing can easily be performed with the routine measurement of TEOAE. It could be useful in the diagnostic of lesions of the cerebello pontine angle and the brain stem.
Otoacoustic emissions of cochlear distortion products (DPOAEs) were measured in normally hearing and hearing-impaired human ears. A total of 133 subjects (231 ears) were tested. Two puretone stimuli f1 and f2 were delivered to a sound probe fixed in the outer ear canal. The frequencies of the two primaries were chosen so that their geometric mean represented pure-tone audiometric frequencies. The otoacoustic emission was measured at the distortion product frequency 2f1-f2 by spectral averaging. For 199 ears, the levels of the primaries were 73 dBHL for L1 and 67 dBHL for L2. Statistical analysis was carried out in 77 ears of 46 subjects with normal hearing (average hearing levels at pure-tone audiometric thresholds less than or equal to 10 dBHL) and 36 ears of 25 subjects exhibiting near-normal hearing (average hearing levels at pure-tone audiometric thresholds less than or equal to 20 dBHL). The mean DPOAE amplitudes were similar in these two groups of ears. In 111 of these 113 ears (98.2%), DPOAEs were detected at three or more of the six tested frequencies between 1 and 6 kHz. DPOAEs were measured in more than 75% of ears at each frequency between 1-6 kHz and in more than 86% between 1-4 kHz. Eighty-six hearing-impaired ears of 44 subjects with sensorineural hearing loss formed the patient group. A highly significant correlation between pure-tone audiometric thresholds and DPOAE amplitudes was demonstrated in the frequency range of 1-4 kHz. Percentiles of DPOAE amplitudes were calculated in 22 ears with a mean pure-tone threshold less than or equal to 5 dBHL and in 12 specially selected pathological ears.(ABSTRACT TRUNCATED AT 250 WORDS)
In a prospective study we examined the effects of cisplatinum on the amplitude of evoked otoacoustic emissions and thus on cochlear micromechanics. 29 patients were examined. Amplitude changes of click-evoked otoacoustic emissions were compared with the threshold of pure-tone audiometry. We observed that an amplitude loss of otoacoustic emissions is a sensitive tool for the early detection of cochlear dysfunction. "Minimal lesions" of the inner ear were observed at an earlier stage during the current therapy than when using conventional audiometry. Measuring and recording otoacoustic emissions enables to diagnose beginning cochlear lesions caused by ototoxic drugs before they become clinically manifest.
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.
The third-octave band levels of the noises produced in a MR-imager (1.0 Tesla Magneton, Siemens) were measured. Corresponding sounds presented through earphones have been used in simulation experiments to produce in normal-hearing listeners a temporary threshold shift lasting several minutes. These effects could be verified objectively using otoacoustic emissions. The consequences especially for patients with already impaired hearing are discussed: ear protection is strongly recommended.
Click-evoked otoacoustic emissions appear to be an efficient way to assess cochlear function in infants and neonates. A new technique developed by Bray and Kemp (1987) enables data to be gathered under clinical conditions. A total of 310 children aged between one day and five years were examined in a realistic clinical situation: 204 of them were admitted to the authors' outpatient department for evaluation of a hearing impairment and 106 were special-care babies or normal newborns. Otoacoustic emissions were successfully tested in 244 of these 310 children at the first attempt after performing behavioural tests. A classification of the emissions by the coefficient of the cross-correlation function and the frequency response spectrum was used. Emissions were observed in 95% (n = 181 ears) of the three- to five-year-old children with a mean behavioural threshold better than 20 dB. In 82% (40/49) of the special-care babies and in 89% (51/57) of the normal newborns a successful emission recording was be obtained. Such findings suggest that this technique for detecting emissions may be useful in early diagnosis of hearing impairments, especially when combined with simple behavioural tests.
This study was designed to estimate and compare measures of cochlear travelling wave delay and travelling wave velocity in normally-hearing adults. Travelling wave delay and velocity measures were estimated in 23 normally-hearing adults using three different test techniques: i) derived auditory brainstem responses (ABR); ii) derived frequency-following responses (FFR); and iii) tone-burst-evoked otoacoustic emissions (TBEOAE). Estimates from ABR and TBEOAE were comparable to each other in terms of both averaged group values and associated standard deviations. Furthermore, mean cochlear travelling wave velocity estimated from ABR and TBEOAE were comparable to published estimates. Average cochlear delays obtained using the derived FFR were significantly shorter than those obtained from the other two techniques, possibly due to the effect of cochlear microphonic contamination. Among the dependent variables investigated, measures of delay are to be preferred over velocity since the latter are based on uncertain values of cochlear distance.
Literature concerning the ototoxicity of the antiseptic combination chlorhexidine/cetrimide (Savlon) is reviewed. The ototoxic effects are illustrated by the results of our own experiments in guinea pigs. The impetus for this article was the observation of vestibular dysfunction in 15 clinical cases (12 dogs and 3 cats), in 8 of which it was confirmed that the ear canal had been rinsed with this drug combination in the presence of a ruptured tympanic membrane.