The Effect of Hydration on Distortion Product Otoacoustic Emission Values in Rats
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Objectives: This study aimed to evaluate the changes that would appear in the inner ear acoustic characteristics of dehydrated and overhydrated rats through distortion product otoacoustic emission (DPOAE). Materials and Methods: The study was conducted with 24 male Sprague Dawey rats. After otoacoustic examinations of the rats were made under general anesthesia, their blood samples were taken, weights were measured. Then, the rats were divided into three groups as dehydration group, overhydration group and control group. Distortion product otoacoustic emission measurements were repeated after 72 hours, and the results were compared. Results: There were no significant differences in the first measurements between three groups in terms of (p>0.05). Weight and osmolarity values differed significantly in the dehydration and overhydration groups following the fluid intake change (p<0.05), but in the control group (p> 0.05). There was a significant decrease in the SNRs at 4004 Hz, 7998 Hz and 9854 Hz frequencies of the overhydration group (p<0.05). On the other hand, there were no significant changes in the DPOAE SNR dB values of the dehydration and control groups (p>0.05). Conclusions: The results of this study indicate that overhydration in rats may change DPOAE values.Keywords:
Otoacoustic emission
Distortion (music)
In the audiologic anamnesis, as for groups I and II, we observed that the main auditory complaints presented by the workers were those of recruitment (29.5%), tinnitus (26.5%), allergy (23.5%) and arterial hypertension (12%). The findings of the audiometry appointed that the research’s individuals did not present with auditory losses in the frequencies of 500 Hz, 1 and 2 kHz, the losses occurred in the frequencies of 3 and 8 kHz. As for the distortion-product otoacoustic emissions (DPOAEs), we observed that the individuals in group III had a major incidence of responses when compared to those of groups I and II. Conclusion: The results analysis allowed us to conclude that the DPOAE test represents an important tool for follow up and prevention of NIHL.
Otoacoustic emission
Anamnesis
Noise-induced hearing loss
Hearing test
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The purpose of this study was to further investigate the possibility of developing noninvasive methods of differential diagnosis of hearing disorders through the study of experimental animals with induced lesions. In particular, it was desired to compare distortion product otoacoustic emission (DPOAE) responses and auditory brain stem response (ABR) thresholds in Mongolian gerbils having either acoustic or strial damage, using as a reference the same responses measured in a control group of normal young adult gerbils. The goal was to evaluate the potential clinical application of this approach to determining the dominant contribution to sensorineural hearing loss in individual human subjects.DPOAE input-output functions and ABR thresholds were measured over a wide range of stimulus frequencies for three groups: (1) a reference group of normal young adult gerbils; (2) a group in which acoustic damage had been induced 2 wk earlier; (3) a group in which damage to the stria vascularis was induced by a series of furosemide injections. The responses in the experimental groups relative to the normal means were compared to determine which combinations of responses were effective in discriminating between animals with different lesions. Three measures were evaluated in detail: the ABR threshold, the emission threshold at a criterion emission amplitude, and the emission amplitude at a high stimulus level.Considering cases with significant hearing loss (ABR thresholds elevated by 20 dB or more), the best method for distinguishing between the two lesions involved a two-dimensional plot comparing emission and ABR thresholds at the same stimulus frequencies. Acoustic damage cases were found in a broad region where the emission and ABR thresholds were roughly equal, whereas strial damage cases were found in a narrower region where the emission threshold was about 0.4 times the ABR threshold (both in dB). These two cases were compared with a third case introduced by definition, that is, damage to inner hair cell or neural systems resulting in an increase in audiometric threshold but no change in emission responses (e.g., auditory neuropathy). The responses for these three cases were found to lie in different regions of the two-dimensional plot comparing emission and ABR thresholds, provided only that ABR thresholds were elevated 20 dB or more. This diagram also revealed cases of preclinical acoustic damage, in which the ABR threshold was shifted less than 20 dB but where the emission threshold was significantly elevated.The results clearly demonstrate the possibility of developing a clinical method of noninvasive differential diagnosis of hearing loss. The method demonstrated was to add to a standard audiometric evaluation the measurement of DPOAE growth functions over the range of frequencies where these emissions were relatively easy to measure and consistent. The DPOAE stimulus frequencies were chosen to match the audiometric frequencies, and the corresponding emission and audiometric thresholds were compared on a threshold-threshold plot for each individual at a number of stimulus frequencies. Responses in different regions in this plot were found to correspond to different types of sensorineural hearing loss.
Otoacoustic emission
Stimulus (psychology)
Presbycusis
Gerbil
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To correlate the annoyance of tinnitus assessed by the Tinnitus Handicap Inventory and on a visual analogue scale with the evoked otoacoustic emission test result in tinnitus patients with normal hearing.Case-control study.Public tertiary hospital.The sample was initially based on a population of 80 subjects with tinnitus; 20 of them had normal hearing and normal evoked otoacoustic emission test results and comprised the study group. For the purpose of comparison, a control group was formed, which consisted of 17 subjects with no hearing complaints and normal hearing. The participants were submitted to hearing tests, immittance testing and tests for the evaluation of acoustic reflexes, distortion product otoacoustic emissions, transient evoked otoacoustic emissions (TEOAEs), and suppression of TEOAEs. The tests were performed in a sound-treated booth using a linear contralateral noise of 60 dB. The presence of suppression effects was defined when the response amplitude was 0.5 dB or higher.Abnormal evoked otoacoustic emission suppression test results were observed in 52.9% of tinnitus patients and in 32.4% of control subjects (p = 0.086). Suppression effects of TEOAEs were absent in 38.5% of subjects with minimal or mild discomfort and in 61.9% of subjects with moderate or severe discomfort (p = 0.183).It was not possible to associate the annoyance caused by tinnitus with the TEOAE suppression test results, although suppression effects were found to decrease with increasing annoyance.
Otoacoustic emission
Annoyance
Acoustic reflex
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Clinical applications of transient evoked otoacoustic emission (TEOAE) measures began in 1989 at Mayo Clinic Rochester. Normative data indicates: a) greater TEOAE level for women and right ears beginning in the teen years, b) mean TEOAE levels remain relatively stable through the first seven decades of life, c) between subject EOAE level variability for normal hearing adults is high (up to about 30 dB) while within subject variability is low (about 4 dB), suggesting EOAEs should not be used to estimate pure-tone thresholds but are valuable in monitoring hearing status. Good frequency specificity of TEOAEs is demonstrated across high frequency hearing loss. Examples of TEOAEs in differential diagnosis are provided for cases of sudden hearing loss, auditory neuropathy and eighth nerve tumors including pre and post operative testing assessing changes in auditory function related to surgical procedures. Finally, our experience with TEOAEs in newborn hearing screening is described.
Otoacoustic emission
Auditory neuropathy
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Citations (30)
Objectives The purpose of this study was to compare the performance of transient evoked otoacoustic emissions (TEOAEs), distortion product otoacoustic emissions (DPOAEs), and auditory brain stem responses (ABRs) as tools for identification of neonatal hearing impairment. Design A total of 4911 infants including 4478 graduates of neonatal intensive care units, 353 well babies with one or more risk factors for hearing loss (Joint Committee on Infant Hearing, 1994) and 80 well babies without risk factor who did not pass one or more neonatal test were targeted as the potential subject pool on which test performance would be assessed. During the neonatal period, they were evaluated using TEOAEs in response to an 80 dB pSPL click, DPOAE responses to two stimulus conditions (L1 = L2 = 75 dB SPL and L1 = 65 dB SPL L2 = 50 dB SPL), and ABR elicited by a 30 dB nHL click. In an effort to describe test performance, these "at-risk" infants were asked to return for behavioral audiologic assessments, using visual reinforcement audiometry (VRA) at 8 to 12 mo corrected age, regardless of neonatal test results. Sixty-four percent of these subjects returned and reliable VRA data were obtained on 95.6% of these returnees. This approach is in contrast to previous studies in which, by necessity, efforts were made to follow only those infants who "failed" the neonatal screening tests. The accuracy of the neonatal measures in predicting hearing status at 8 to 12 mo corrected age was determined. Only those infants who provided reliable, monaural VRA test results were included in the analysis. Separate analyses were performed without regard to intercurrent events (i.e., events between the neonatal and VRA tests that could cause their results to disagree), and then after accounting for the possible influence of intercurrent events such as otitis media and late-onset or progressive hearing loss. Results Low refer rates were achieved for the stopping criteria used in the present study, especially when a protocol similar to the one recommended in the National Institutes of Health (1993) Consensus Conference Report was followed. These analyses, however, do not completely describe test performance because they did not compare neonatal screening test results with a gold standard test of hearing. Test performance, as measured by the area under a relative operating characteristic curve, were similar for all three neonatal tests when neonatal test results were compared with VRA data obtained at 8 to 12 mo corrected age. However, ABRs were more successful at determining auditory status at 1 kHz, compared with the otoacoustic emission (OAE) tests. Performance was more similar across all three tests when they were used to identify hearing loss at 2 and 4 kHz. No test performed perfectly. Using either the two- or three-frequency pure-tone average (PTA), with a fixed false alarm rate of 20%, hit rates for the neonatal tests, in general, exceeded 80% when hearing impairment was defined as behavioral thresholds ≥30 dB HL. All three tests performed similarly when a two-frequency (2 and 4 kHz) PTA was used as the gold standard; OAE test performance decreased when a three-frequency PTA (adding 1 kHz) was used as the gold standard definition. For both PTA and all three neonatal screening measures, however, hit rate increased as the magnitude of hearing loss increased. Conclusions Singly, all three neonatal hearing screening tests resulted in low refer rates, especially if referrals for follow-up were made only for the cases in which stopping criteria were not met in both ears. Following a protocol similar to that recommended in the National Institutes of Health (1993) Consensus Conference report resulted in refer rates that were less than 4%. TEOAEs at 80 dB pSPL, DPOAE at L1 = 65, L2 = 50 dB SPL and ABR at 30 dB nHL measured during the neonatal period, and as implemented in the current study, performed similarly at predicting behavioral hearing status at 8 to 12 mo corrected age. Although perfect test performance was never achieved, sensitivity for each measure increased with the magnitude of hearing loss. This latter finding is important because it suggests that all three tests performed better at identifying hearing losses for which intervention would be immediately recommended.
Otoacoustic emission
Monaural
Stimulus (psychology)
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Objective To detect the early hearing impairment induced by noise in pilots. Methods Thirty pilots with normal pure tone hearing thresholds served as subjects and 15 normal volunteers as controls. Transient evoked otoacoustic emission (TEOAE) and distortion-product evoked otoacoustic emission (DPOAE) were recorded with Capella acoustic emission machine, and the results of 2 groups were compared and analyzed. Results As compared with those of controls, the DPOAE amplitudes at high frequencies, the wave signal noise ratio (SNR), wave reproducibility, band SNR and band reproducibility of TEOAE were significantly lowered. Conclusions It is suggested that early hearing impairment may exist in pilots with normal pure tone hearing thresholds. TEOAE and DPOAE may be used to detect the early hearing impairment dynamically in pilots.
Otoacoustic emission
Tone (literature)
Pure tone
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The present study was to evaluate the audiological characteristics of infants with normal auditory brainstem response thresholds in click and abnormal transiently evoked otoacoustic emissions. Relationships between test results of distortion product otoacoustic emissions (DPOAE) and other hearing testing methods were also evaluated.The participants consisted of eighty-nine infants, with a total of 123 ears. All participants' TEOAE screening results were abnormal but diagnostic click ABR results were normal. The participants were classified into the following groups based on the test results from distortion product otoacoustic emissions: group A (normal all-frequency), group B (abnormal low-frequency), group C (abnormal high-frequency), and group D (abnormal all-frequency).Obtained from these groups were compared to results of other hearing tests including the latency of ABR wave I, 40 Hz auditory event related potential (40 Hz AERP), 226 Hz and 1000 Hz tympanometry, and acoustic reflex. Results In six hearing tests in the 123 ears, seven ears (5.7%) were normal, while 116 ears (94.3%) were abnormal. No significantly differences were detected between boys (93.9%) and girls (95.1%), as well as between left (93.1%) and right ears (95.4%). The proportion of abnormal test results ranked as follows: 59 ears in group D (48.0%), 34 ears in group B (27.6%), 20 ears in group A (16.3%), and 10 ears in group C (8.2%). The highest abnormal rates in groups A, B and D were acoustic reflex, which were 40.0% for group A, 55.9% for group B and 66.1% for group D respectively. The highest abnormal rate in group C was the latency of ABR wave I (50.0%). Distribution of low-frequency hearing loss in each group was mainly mild. However, one ear in group B was moderate hearing loss, six ears in group D were moderate hearing loss, and one ear in group D was severe hearing loss.The present study showed that, of which infants with normal thresholds of ABR failed the hearing screening, comprehensively audiology assessment is needed. And of which infants with normal DPOAE in full frequency or abnormal in high frequency region or low frequency region need to be followed up.
Tympanometry
Otoacoustic emission
Acoustic reflex
Auditory brainstem response
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The aim of the study was to assess age-related changes of the transient evoked otoacoustic emissions (TEOAE) and distortion product otoacoustic emissions (DPOAE) as well as to evaluate age-related changes of DPOAE suppression in adult subjects with normal hearing and presbycusis. Only women participated in the study: 26 young women with normal hearing (20-31 years old) were included into the first group; the second group consisted of 28 elderly (60-74 years old) with normal hearing; the third group included 28 elderly women with presbycusis (mild-to-moderate hearing loss). Age-related decrease of prevalence and amplitude of OAEs was proved to be significant; no significant differences of these data for left and right ears were revealed. Contralateral suppression of DPOAE was noted more often and was the greatest in young listeners and was presented in all frequency range, meanwhile the suppression was minimal and rarely noted in patients with presbycusis. The DPOAE amplitude enhancement in the contralateral noise condition was recorded in all groups of listeners, more often in aged patients both with normal hearing and hearing loss. These results may indicate age-related changes of medial olivocochlear complex, which take place not only in patients with hearing loss but in normal hearing subjects as well.. The findings were confirmed by the results of acoustic reflex measurements obtained in this study.Цель исследования - оценить возрастные изменения задержанной вызванной отоакустической эмиссии (ЗВОАЭ) и отоакустической эмиссии на частоте продукта искажения (ОАЭПИ), а также эффекта подавления ОАЭПИ у взрослых испытуемых с нормальным слухом и с пресбиакузисом. Для обследования отбирались только женщины: в 1-ю группу вошли 26 молодых (20-31 года) испытуемых с нормальным слухом, во 2-ю - 28 пожилых (60-74 лет) женщин с нормальным слухом, в 3-ю - 28 пожилых пациенток с пресбиакузисом (с 1-2-й степенью снижения слуха). Установлено достоверное уменьшение частоты встречаемости и амплитуды ОАЭ с возрастом; статистически значимых различий этих показателей для левого и правого ушей ни в одной из групп не выявлено. Эффект подавления ОАЭПИ на фоне контралатерального предъявления шума наиболее часто отмечался и был максимально выражен в группе молодых испытуемых, у которых он прослеживался на всех исследуемых частотах, а реже всего и с минимальной выраженностью - у пациенток с пресбиакузисом. Во всех группах испытуемых наряду с подавлением ОАЭПИ выявлен феномен роста амплитуды ОАЭПИ, наиболее часто встречающийся у пожилых пациенток, как с нормальным слухом, так и с тугоухостью. Достоверно худшие показатели подавления ОАЭПИ и более частый рост ОАЭПИ при контралатеральном предъявлении шума у пожилых испытуемых в сравнении с молодыми могут указывать на изменения медиального оливокохлеарного комплекса, развивающиеся с возрастом не только при тугоухости, но и при сохранном слухе, что подтверждается данными регистрации акустического рефлекса, полученными в настоящем исследовании.
Presbycusis
Otoacoustic emission
Acoustic reflex
Age groups
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Previous research has reported reduced otoacoustic emission amplitude as a function of age. In each study, however, interpretation of findings was confounded by age-related hearing loss. The present study was designed to re-evaluate the contribution of age and peripheral hearing loss on the prevalence and amplitude of distortion-product otoacoustic emissions (DPOAEs) by controlling for degree of peripheral hearing loss. Twenty subjects were divided into four age ranges. All subjects in each group had 15 dB HL or better thresholds from 0.25 through 8 kHz and normal immittance findings. DPOAE audiograms recorded at three intensity levels and input/output functions recorded at six discrete frequencies showed no significant differences in amplitude or noise level between age groups. Findings indicate that when the degree of peripheral hearing loss is adequately controlled, there is no direct effect of advanced age on DPOAE measures. Clinical implications are discussed.
Audiogram
Otoacoustic emission
Immittance
Noise-induced hearing loss
Age groups
Presbycusis
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