Is the real-ear to coupler difference independent of the measurement earphone?

Direct measurement of real-ear hearing aid performance can be obtained using a probe tube microphone system. Alternatively, it can be derived by adding the real-ear to coupler difference (RECD) to the electroacoustic performance of the hearing instrument measured in a 2-cc coupler. Inherent in this derivation is the assumption that the RECD measured with one transducer can be applied to a coupler measurement performed with a different transducer. For the RECD procedure to be valid, it should be independent of the measurement transducer. The Audioscan RM500 is an example of a commercially available real-ear measurement system that incorporates a clinical protocol for the measurement of the RECD. The RECD can be measured on the Audioscan RM500 using a standard EAR-Tone ER-3A insert earphone or the Audioscan's own RE770 insert earphone. The aim of this study was to compare the RECDs obtained with these two earphones. The Audioscan RM500 was used to measure the RECD from the right ears of 18 adult subjects ranging in age from 22 to 36 years (mean 25 years). Measurements were made with the EAR-Tone ER-3A and RE770 insert earphone and three earmould configurations: (1) the EARLINK foam ear-tip; (2) a hard acrylic shell earmould with the same length of acoustical tubing as the foam ear-tip (25 mm); and (3) the shell ear mould with the appropriate length of tubing for a behind-the-ear (BTE) hearing aid fitting (approximately 35-45 mm). The results show that the mean RECD was around 3 dB higher at 1.5 kHz with the foam ear-tip when measured with the RE770 earphone than when measured with the ER-3A earphone. The same magnitude of difference was obtained with the shell earmould and 25-mm tubing; however, this increased to 9 dB when the tubing was increased to around 40 mm for a BTE fitting. The difference in mean RECD with the two earphones was statistically significant on a repeated-measures ANOVA for every earmould configuration (p<0.001). The results of this study demonstrate that the RECD procedure that uses an HA2 coupler and earmould is not independent of the measurement earphone. This has important implications for clinical practice.     

Earphones in extended high-frequency audiometry and ISO 389-5

Abstract

Objective: To determine common reference equivalent threshold sound pressure levels (RETSPL) for the earphones used in the extended high-frequency (EHF) range, as different earphones are commercially available, but there are not RETSPLs for each model. Design: Hearing threshold sound pressure levels were measured up to 20 kHz for the Sennheiser HDA 200 audiometric earphone, and were compared to the ISO 389-5 (2006) norm and other investigations using that earphone and different ones. Study sample: A total of 223 otologically-normal subjects (aged 5–25 years old) participated in the hearing determination. Results: The results are in good agreement with previous studies of hearing thresholds using the same and other earphones. Conclusions: The results of the present investigation are relevant for the international standard for the calibration of audiometric equipment in the 8 to 16 kHz frequency range, ISO 389-5. The data may be used for a future update of the RETSPL for circumaural and insert audiometric earphones.     

The influence of RECD transducer when deriving real-ear sound pressure level

OBJECTIVE: The main aim of the present study was to compare the derived and directly measured real-ear hearing instrument performance for a range of commonly used hearing instruments. A secondary aim was to compare the real-ear to coupler difference (RECD) measured using the ER-3A insert earphone and a selection of hearing instruments. DESIGN: The real-ear SPL was measured for four models of hearing instrument in 20 adult participants using an Audioscan RM500 real-ear system. This was compared with the derived real-ear SPL obtained by adding the RECD (measured using the ER-3A insert earphone) to the 2-cc coupler response of each hearing instrument. Measurements were made at 1/12 octave intervals from 0.2 to 6 kHz, using both the HA1 and HA2 2-cc coupler. In addition, the RECD was measured using four models of hearing instrument for comparison with the ER-3A insert earphone values. RESULTS: The procedures were very reliable with mean differences on retest of less than 1 dB. Repeated-measures analysis of variance revealed statistically significant differences between the measured and derived real-ear SPL (p < 0.001) for several models of hearing instrument. The derived responses using the HA1 coupler yielded good accuracy, whereas the HA2 yielded less accuracy. For three models of hearing instrument, the maximum difference was between 5 and 10 dB when using the HA2 coupler. The mean RECD measured with the ER-3A insert earphone and HA2 coupler was not always equivalent to the RECD measured with the hearing instruments. CONCLUSIONS: The accuracy of the derived real-ear response obtained using an RECD, measured with an ER-3A insert earphone, is very good when an HA1 is used for the coupler component of the RECD. The accuracy diminishes somewhat with the HA2 coupler, especially for undamped hearing instruments. The accuracy of the derived real-ear response is very good when the RECD is measured using the hearing instrument and the HA1 or the HA2 coupler.     

Modification of otoacoustic emissions following ear-level exposure to MP3 player music

The purpose of this study was to examine if a pre-determined exposure level and duration of MP3 player music would result in significant changes in cochlear function when measured with audiometric and physiological methods. Distortion-product otoacoustic emissions (DPOAEs), synchronized spontaneous otoacoustic emissions (SSOAEs), and hearing thresholds were measured in 20 normal-hearing adults before and after a 30-minute MP3 player music exposure. DPOAEs were acquired with 65/45 dB SPL primary tones (f₂=0.842–7.996 kHz) with a frequency resolution of 8 points/octave. A probe microphone system recorded ear-canal music levels and was used to equalize levels at approximately 85 dBC across individuals during the music presentation. Comparison of pre- and post-exposure measurements revealed no significant differences in hearing thresholds, but DPOAE levels in half-octave bands centered from 1.4–6.0 kHz were significantly reduced following the music exposure. Post-exposure shifts in SSOAE frequency and level were highly variable in individuals identified with SSOAEs. The results for the exposure conditions explored in this study indicate that changes in otoacoustic emissions may precede the development of music-induced hearing threshold shifts.     

Test-retest variability in audiometric threshold with supraaural and insert earphones among children and adults

The effect of age and earphone condition on test-retest intrasubject variability in audiometric threshold was investigated. Ten subjects in each of the following age groups were investigated: 6-9 years, 10-13 years and young adults. Test-retest audiometric thresholds were collected at six frequencies (250, 500, 1,000, 2,000, 4,000 and 8,000 Hz) under three earphone conditions (Telephonics TDH-50P supraaural and Etymotic Research ER-3A insert earphone coupled to an immittance probe cuff or a foam insert). No statistically significant differences were found in variability of test-retest differences as a function of age, earphone condition or test frequency (p greater than 0.05). The clinical application of the insert earphone is recommended with children and adults as it affords no greater test-retest variability and at the same time provides a solution to a number of limitations incurred with the use of the supraaural earphone.     

噪声暴露工人畸变产物耳声发射和扩展高频测听的研究

目的 :分析畸变产物耳声发射 (DPOAE)和常频纯音测听、扩展高频测听的关系 ,借以探讨DPOAE的产生机制以及在噪声性听力损伤的监测和早期诊断中的应用价值。方法 :对 4 2例耳科正常人 (对照组 )和 2 0例噪声暴露工人 (实验组 )进行 0 .5～ 16 .0kHzDPOAE、常频纯音测听及扩展高频测听的检测 ,比较对照组和实验组DPOAE和常频纯音测听、扩展高频测听的结果。结果 :实验组纯音听阈在 6 .0kHz处和扩展高频区下降明显 ,与对照组比较 ,差异有显著性意义 (P <0 .0 5 ) ;DPOAE幅值在 4 .0、6 .0和 11.2kHz处下降明显 ,与对照组比较 ,差异均有显著性意义 (P <0 .0 5 ) ;而在 12 .5、14 .0、16 .0kHz 3个频率处两组差异无显著性意义 (P >0 .0 5 )。结论 :常频DPOAE检查可用于噪声性聋的早期诊断和监测。DPOAE可能来源于对应频率区及较高频率区耳蜗外毛细胞 ,其产生部位和机制尚待深入研究     

扩展高频畸变产物耳声发射在纯音听阈正常的耳鸣患者中的临床应用

目的 分析纯音听阈正常的耳鸣患者扩展高频畸变产物耳声发射(EHF DPOAE)的特点，探讨在常规纯音检测结果正常情况下，EHF DPOAE发现早期隐匿性听力损失的临床意义。方法 选取常规纯音听阈正常的耳鸣患者68例(104耳)为实验组，对照组为纯音听阈正常无耳鸣症状的志愿者40例(40耳)。两组均用Neuro-Audio耳声发射仪进行常规频率(1～6 kHz)畸变产物耳声发射(DPOAE)测试、EHF DPOAE(8～12 kHz)测试。结果 对照组常规频率DPOAE的平均检出率为97.2%,EHF DPOAE的检出率为88.7%;实验组常规频率DPOAE的检出率为72.2%,EHF DPOAE的检出率为51.2%。实验组EHF DPOAE引出率明显低于对照组EHF DPOAE引出率(P<0.001);实验组EHF DPOAE中振幅值明显低于对照组EHF DPOAE的振幅值(P<0.001);实验组EHF DPOAE的平均信噪比值明显低于对照组EHF DPOAE的平均信噪比值(P<0.001)。结论 在常规纯音听力检测正常的特发性耳鸣患者中，EHF DPOAE的引出率...     

Evaluation of the possible effect of magnetic resonance imaging noise on peripheral hearing organ with the otoacoustic emission

PurposeThe aim of this study is to evaluate the effect of noise produced by magnetic resonance imaging (MRI) device on hearing by using objective and subjective audiological assessments.MethodsA total of 38 patients between the ages of 18 and 50 without hearing loss, and had performed MRI for brain, head, neck or cervical imaging were included in this prospective clinical study. Pure tone audiometry, speech audiometry, high frequency audiometry, transient evoked otoacoustic emissions (TEOAE) and distortion product otoacoustic emission (DPOAE) were performed before and after MRI.ResultsThere was no statistically significant difference in TEOAE, pure tone audiogram, high frequency audiogram and speech audiogram thresholds. In DPOAE, the median value before and after MRI at the frequency of the left ear at 4.0 kHz was 13.6 (8.5–19.9) and 15.7 (8.9–20.7) SNR respectively (p > .05). The median value before MRI at the right ear 4.0 kHz frequency was 14.1 (9.1–20.5) SNR, whereas the median value after MRI was 13.2 (8.8–19.8 SNR (p = 0,03). There was no statistically significant difference in other frequencies in DPOAE.ConclusionsThis is the first objective study that examines the MRI noise on speech audiometry and otoacoustic emission together. However, the effect of MRI noise on hearing pathway is still doubt. Based on the difference at 4 kHz frequency on DPOAE; on-earphones may not sufficiently protect the patients from the MRI noise and this issue should deserve further research.     

AMTAS®: Automated method for testing auditory sensitivity: III. Sensorineural hearing loss and air-bone gaps

Abstract

Objective: The objectives were to measure the occlusion effect produced by three earphones—circumaural, supra-aural, and insert—and to compare air- and bone-conduction thresholds obtained with manual and automated methods for subjects with sensorineural hearing loss. Design: Acoustic and psychoacoustic occlusion effects were measured with each earphone. Manual and automated, air- and bone-conduction thresholds were compared. Study sample: Occlusion effects were measured for six adult subjects with normal external and middle ears. Pure-tone thresholds were measured for nineteen ears of thirteen subjects with sensorineural hearing loss. Results: The supra-aural earphone produced the largest occlusion effects, followed by the insert and circumaural earphones. Some systematic differences in air-conduction thresholds were found for the two procedures that may be attributable to earphone differences. A large air-bone gap at 4 kHz, reported in a previous study, was replicated. Conclusions: From 0.5 to 8.0 kHz, occlusion effects produced by the circumaural earphone are sufficiently small that covering the ear does not appreciably alter bone-conduction thresholds. Air-conduction threshold differences warrant further study to determine if reference equivalent threshold sound pressure levels for the two earphones produce equivalent thresholds. The large air-bone gap at 4 kHz suggests the possibility of an incorrect reference equivalent threshold force level at that frequency.

Sumario

Objetivo: Los objetivos fueron medir el efecto de oclusión producido por tres auriculares – circumaural, supra-aural y de inserción – y comparar umbrales de conducción aérea y ósea obtenidos con métodos manuales y automatizados para sujetos con hipoacusia sensorineural. Diseño: Se midieron los efectos de oclusión acústicos y psicoacústicos con cada auricular. Se compararon los umbrales de conducción aérea y ósea manuales y automatizados. Muestra del Estudio: Se midieron los efectos de oclusión para seis sujetos adultos con oídos externos y medios normales. Resultados: Los auriculares supra-aurales produjeron los mayores efectos de oclusión, seguidos de los auriculares de inserción y los circumaurales. Se encontraron algunas diferencias sistemáticas en los umbrales de conducción aérea para los dos procedimientos que pueden atribuirse a las diferencias en los auriculares. Una gran brecha aéreo-ósea en 4 kHz que se reportó en un estudio previo, fue replicada. Conclusiones: De 0.5 a 8 kHz, los efectos de oclusión producidos por los auriculares circumaurales son lo suficientemente pequeños por lo que cubrir el cubrir el oído no altera apreciablemente los umbrales de conducción ósea. Las diferencias en los umbrales de conducción aérea exigen estudios adicionales para determinar si los niveles umbrales equivalentes de referencia de presión sonora para los dos auriculares producen umbrales equivalentes. La mayor brecha aéreo-ósea en 4 kHz sugiere la posibilidad de un nivel de referencia equivalente de fuerza umbral en esa frecuencia.     

A comparison of inter-aural attenuation with the Etymotic ER-3A insert earphone and the Telephonics TDH-39 supra-aural earphone.

One of the many reported advantages of the insert earphone over the supra-aural earphone is increased inter-aural attenuation (IA). Minimum values of IA determine the need for masking of the non-test ear in air-conduction audiometry. The aim of the present study was to measure inter-aural attenuation for the Etymotic Research ER-3A insert earphone (with deep and shallow insertion of the ear plug within the ear canal) and compare this with the supra-aural Telephonics TDH-39/MX41-AR earphone/cushion combination. Subjects were 18 adults ranging in age from 38 to 68 years (mean 50 years). Each subject had no hearing in one ear following translabyrinthine surgery for removal of an acoustic neuroma. The opposite ear had hearing thresholds better than 40 dB HL and an air-bone gap of less than 10 dB at any audiometric frequency. Pure tone air-conduction thresholds were obtained in the range 0.25-8 kHz. Deep insertion of the insert earphone was deemed to occur when the outside edge of the ear plug was flush with the entrance of the ear canal. Shallow insertion was deemed to occur when half of the ear plug (6 mm) was inside the entrance of the ear canal. IA was defined operationally as the difference between the good-ear and poor-ear not-masked air conduction threshold for a given audiometric frequency and earphone. The results show that the TDH-39/MX41-AR combination provides a median IA of approximately 60 dB with a lower limit of approximately 45 dB. Greater IA was obtained with the ER-3A insert earphone but this depended on the depth of insertion. With a deep insertion, the 1A values were some 15-20 dB greater than with the supra-aural earphone. Although frequency-specific IA values are provided, a simple rule of thumb is to apply masking to the non-test ear when the pure tone airconduction signal from the ER-3A insert earphone exceeds the bone conduction threshold of the non-test ear by 55 dB HL or more. If it is not possible to obtain a deep insertion depth this value should be reduced by 5 dB.     

A comparison of the variability in thresholds measured with insert and conventional supra-aural earphones

The purpose of this study was to evaluate the reliability and comparability of the commercially available insert earphone Etymotic Research ER-3A and the commonly available supra-aural TDH earphone. Thirteen subjects were tested five times with the ER-3A and five times with TDH-49P with MX-41/AR cushions. Threshold determinations were obtained utilizing a sweep-frequency audiometer in the range 0.25-8 kHz. The results showed that the reliability of the ER-3A earphone as measured by intra-individual variation, was comparable to that obtained with the TDH earphone. No evidence was found indicating an increased variability due to the positioning of the insert earphone's coupling device in the ear canal. Comparison of thresholds obtained with both devices indicated that the manufacturer's suggested correction values were appropriate.     

Reference hearing threshold levels for chirp signals delivered by an ER-3A insert earphone

Abstract

Objective: To establish reference hearing threshold levels for chirps and frequency-specific chirps. Design: Hearing thresholds were determined monaurally for broad-band chirps and octave-band chirps using the Etymotic Research, ER-3A insert earphone. The chirps were presented using two repetition rates, 20 and 90 stimuli/s, and with alternating polarity in blocks of one second duration. The test procedure and test conditions were in accordance with the recommendations given in . The ascending method () was applied using a step size of 5 dB. The chirps were played back from a Tucker Davies Technologies System II, and a Matlab program controlled the test setup. The results are specified in dB peak-to-peak equivalent threshold sound pressure levels (dB peETSPL). Study sample: The test group consisted of 25 otologically-normal young adults (age 18–25 years). Results: The results are in good agreement with the results from another investigation of hearing thresholds using the same chirp stimuli, and the values for the octave-band chirps are in line with the standardized reference values for corresponding tone bursts (). Conclusions: The results of the present investigation are relevant for the international standard on short duration signals, .     

Correlation between DPOAE I/O functions and pure-tone thresholds

Different studies have been carried out in order to correlate audiometric thresholds and distortion product otoacoustic emissions measurements (DPOAE). However, high variability and external interferences make hearing thresholds estimates by means of the DPOAE very little sensitive. The aim of this study was to check the correspondence between the pure tone thresholds and the cochlear response thresholds by DPOAE Input/output functions, considering the influence of the following variables: gender, past of acute otitis media, and ear side.MethodProspective study comprehending 69 normal hearing individuals. Multiple mix regression models were applied to evaluate the correspondence between the two measurements studied.ResultsStatistically significant positive correlation was observed among all the frequencies compared (2000, 3000, 4000 e 6000 Hz).ConclusionsThe 1dB HL resolution pure tone thresholds and the above-mentioned variables had a direct impact on the high correlation between the measures studied, and it also reduced response variability. Nevertheless, response variability was still high, limiting the use of DPOAE I/O functions for hearing threshold estimates. We suggest that these variables should be considered for future studies with pure tone thresholds estimations by DPOAE I/O functions.     

Influence of ultrahigh-frequency hearing thresholds on distortion-product otoacoustic emission levels at conventional frequencies

This study examined the association between ultrahigh-frequency (UHF) hearing sensitivity and distortion-product otoacoustic emission (DPOAE) levels at conventional frequencies. Behavioral thresholds were measured from 2 through 16 kHz, and DPOAE levels were measured at discrete f2 frequencies between 2 through 8 kHz in 553 young normal-hearing adult male participants. A DPOAE frequency sweep was measured with primary stimulus levels of L1/L2 = 65/55 dB SPL and an f2/f1 of 1.2. Significant negative correlations, although weak, were found between UHF behavioral thresholds and DPOAE levels. As UHF behavioral thresholds worsened, DPOAE levels decreased at all frequencies. When the data were categorized into two groups, "better" and "worse" UHF behavioral thresholds, significant differences were apparent between the two groups for DPOAEs. Additionally, those with better UHF thresholds had better conventional thresholds compared to those in the worse UHF threshold group. The results of this age-restricted, large-sample-size study confirm and augment findings from earlier studies demonstrating that UHF hearing sensitivity has some influence on DPOAE measures at frequencies from 2 through 8 kHz with moderate stimulus levels. However, because those with better UHF thresholds also had better conventional thresholds and the significant correlations found were weak, this work supports the importance of UHF hearing testing in conjunction with otoacoustic emission measures to identify basal cochlear insults not evident from behavioral testing at conventional frequencies.     

Development of distortion product otoacoustic emissions in C57BL/6J mice

Distortion product otoacoustic emissions (DPOAEs) have been used to examine the development of hearing in the rat and gerbil. However, no reports of DPOAE measurement from the onset of hearing in mice are available. Commercially-available components were assembled and adapted to provide a suitable probe microphone and sound delivery system for measuring DPOAE in developing C57BL/6J mice. Furthermore, DPOAE data were compared with the findings of the auditory brainstem response (ABR). DPOAEs were obtained at 8 kHz from 11 days after birth, 20 kHz from 12 days, and 30 kHz from 13 days. Adult-like patterns of DPOAE were obtained 21 days at 8 and 20 kHz, and 28 days at 30 kHz. On the other hand, the ABR thresholds at 12 to 36 kHz appeared between 11 and 12 days and were saturated at 14 days. Based on these data, the onset of measureable DPOAEs in the mouse were earlier than in the rat and gerbil. The maturation of DPOAE in the mouse begins at a lower frequency in the high frequency range. In addition, the ABR threshold reached maturation earlier than DPOAE.     

Comparison of real-ear to coupler difference values in the right and left ear of adults using three earmold configurations

OBJECTIVE: The purpose of the study was to compare real-ear to coupler difference (RECD) values in the right and left ear of adults using three earmold configurations. DESIGN: The RECD was obtained from both ears of 18 normal hearing adults by subtracting the HA2 2-cc coupler response from the real-ear response using an ER-3A insert earphone and a swept pure tone on the Audioscan RM500 probe-tube microphone system. The measurements were made with a personal earmold, foam eartip, and oto-admittance tip. RESULTS: The mean difference between the right and left RECD was close to 0 dB for all earmold configurations and was not statistically significant on a repeated-measures analysis of variance (p > 0.05). In 90% of participants, the difference between ears was generally less than 3 dB at 0.5 to 4 kHz. CONCLUSIONS: Cooperative participants with non-occluding wax and normal middle ear function (on tympanometry) show small differences in RECD between the right and left ear, irrespective of the earmold configuration. The study has yet to be extended to the clinical setting where subject cooperation and earmold fit may differ from the present study. In the meantime, the findings from the present study indicate that where an RECD can be obtained from only one ear of a participant, it is probably best to use this to derive real-ear SPL of both ears instead of relying on average age appropriate corrections.     

Occupational exposure to noise decreases otoacoustic emission efferent suppression

With the discovery of otoacoustic emissions (OAEs), the efferent cochlear system has become accessible for investigation in humans. Recently, it has been suggested that contralateral sound activated OAE efferent suppression may provide an early indication of auditory damage due to exposure to noise. In this study, OAE efferent suppression in normally hearing subjects, occupationally exposed to noise, was compared with respective effects in healthy, non-exposed subjects. The noise-exposed group exhibited higher mean hearing thresholds at frequencies 4, 6 and 10 kHz (p < 0.01) and lower-level transient-evoked otoacoustic emission (TEOAE) and distortion-product otoacoustic emission (DPOAE) at a frequency of 4 kHz (not significant). TEOAE efferent suppression was moderately decreased, whereas DPOAE efferent suppression was negligible, in the exposed group compared to non-exposed subjects. The results of the study suggest that OAEs, particularly DPOAE contralateral suppression, are likely to become a valuable method for assessing early hearing damage caused by exposure to noise.     

纯音听阈正常的耳闷患者诱发性耳声发射分析

目的:对纯音听阈正常的耳闷患者进行诱发性耳声发射分析,以早期发现这些患者的耳蜗损害.方法:采用丹麦Madsen公司Capella耳声发射仪对纯音听阈正常的耳闷患者43例(72耳,耳闷组)及正常人30例(60耳,对照组)分别进行TEOAE及DPOAE检测,记录和分析各频率DPOAE的检出率、幅值,TEOAE的通过率、反应波信噪比、波形重复性及各频带反应波信噪比和重复性.结果:①DPOAE检出率仅在0.50、0.75 kHz两频点上耳闷组明显低于对照组(P＜0.05),其余各频率点差异均无统计学意义(P＞0.05);②TEOAE通过率对照组为100%,耳闷组为90.28%,2组比较差异有统计学意义(X2=6.16,P＜0.05);③与对照组相比,纯音听阈正常的耳闷患者各频率DPOAE的幅值、TEOAE的反应波信噪比、波形重复性及各频带反应波信噪比和重复性均降低,差异有统计学意义(P＜0.05或P＜0.01).结论:部分纯音听阈正常的耳闷患者已存在耳蜗外毛细胞的损害,利用诱发性耳声发射的方法可在其听力损失出现之前早期发现此类病变.     

Contralateral inhibition of distortion product otoacoustic emissions in children with auditory processing disorders

Abstract

Objective: The purpose of this study was to evaluate changes in distortion product otoacoustic emission (DPOAE) level elicited by contralateral noise in children with normal hearing, and those with auditory processing disorders (APD) whose audiometric thresholds were normal. It was hypothesized that children with APD would demonstrate smaller changes. Design: Levels of DPOAEs were recorded for f₂ stimulus tones fixed at 2, 3, and 4 kHz while the f₁ tone was ramped around nominal stimulus frequency ratios of f₂/f₁ = 1.22 and 1.10. Mean and maximum absolute changes resulting from contralateral broadband noise presented at 60 dB SPL were evaluated across the DPOAE frequency bands for each individual and for both groups of subjects. Study sample: Eight normal-hearing children and eight children with APD whose audiometric thresholds were normal participated. Results: There were no significant differences in DPOAE inhibition between normal hearing and APD groups, or previously recorded adult data. Mean absolute changes were typically near 1 dB, except for f₂ = 4 kHz and the stimulus frequency ratio 1.22 where inhibition was only 0.5 dB. However, there were individual children in both groups who demonstrated larger DPOAE changes for some stimulus parameters. Conclusions: The inhibition of otoacoustic emissions requires further study in APD children.

Sumario

Objetivo: El propósito de este estudio fue evaluar los cambios en el nivel de las emisiones otoacústicas por productos de distorsión (DPOAE) generados por ruido contralateral, en niños con audición normal y en aquellos con trastornos de procesamiento auditivo (APD), cuyos umbrales audiométricos era normales. Se planteó la hipótesis que los niños con ADP demostrarían cambios menores. Diseño: Se registraron los niveles de DPOAE para tonos de estímulo f₂ fijos a 2, 3 y 4 KHz, mientras que el f₁ fue colocado cercano a tasas nominales de frecuencia del estímulo f₁/f₂ = 1.22 y 1.10. Los cambios medios y máximos absolutos que resultaron del ruido de banda ancha contralateral a 60 dB SPL fueron evaluados en todas las bandas de frecuencias de las DPOAE para cada individuo y para ambos grupos de sujetos. Muestra del Estudio: Participaron ocho niños con audición normal y ocho niños con APD, cuyos umbrales audiométricos eran normales. Resultados: No hubo diferencias significativas en la inhibición de las DPOAE entre los grupos con audición normal y con APD, o con información de adultos previamente registrada. Los cambios medios absolutos estuvieron típicamente cerca de 1 dB, excepto para f₂ = 4 kHz, para la tasa de frecuencia del estímulo de 1.22, donde la inhibición fue solo 0.5 dB. Sin embargo, hubo niños individuales en ambos grupos que demostraron cambios mayores en DPOAE para algunos parámetros de estímulo. Conclusiones: La inhibición de las emisiones otoacústicas requiere de más estudio en niños con APD.     

Diplacusis, hearing threshold and otoacoustic emissions in an episode of sudden, unilateral cochlear hearing loss

Limited data are available on the relationship between diplacusis and otoacoustic emissions and sudden hearing threshold changes, and the detail of the mechanism underlying diplacusis is not well understood. Data are presented here from an intensively studied single episode of sudden, non-conductive, mild hearing loss with associated binaural diplacusis, probably due to a viral infection. Treatment with steroids was administered for 1 week. This paper examines the relationships between the hearing loss, diplacusis and otoacoustic emissions during recovery on a day-by-day basis. The hearing thresholds were elevated by up to 20 dB at 4kHz and upwards, and there was an interaural pitch difference up to 12% at 4 and 8 kHz. There was also a frequency-specific change in transient evoked otoacoustic emission (TEOAE) and distortion-product otoacoustic emission (DPOAE) level. DPOAE level was reduced by up to 20 dB. with the greatest change seen when a stimulus with a wide stimulus frequency ratio was used. Frequency shifts in the 2f2-fi DPOAE fine structure corresponded to changes in the diplacusis. Complete recovery to previous levels was observed for TEOAE, DPOAE and hearing threshold. The diplacusis recovered to within normal limits after 4 weeks. The frequency shift seen in the DPOAE fine structure did not quite resolve, suggesting a very slight permanent change. The time-courses of TEOAE. diplacusis and hearing threshold were significantly different: most notably, the hearing threshold was stable over a period when the diplacusis deteriorated. This suggests that the cochlear mechanisms involved in diplacusis, hearing threshold and OAE may not be identical.