Changes in otoacoustic emissions and high-frequency hearing thresholds in children and adolescents

A longitudinal study investigating the effects of noise exposure on behavioural, electrophysiological and self-report measures of hearing in musicians with normal audiometric thresholds

Musicians are at risk of hearing loss and tinnitus due to regular exposure to high levels of noise. This level of risk may have been underestimated previously since damage to the auditory system, such as cochlear synaptopathy, may not be easily detectable using standard clinical measures. Most previous research investigating hearing loss in musicians has involved cross-sectional study designs that may capture only a snapshot of hearing health in relation to noise exposure. The aim of this study was to investigate the effects of cumulative noise exposure on behavioural, electrophysiological, and self-report indices of hearing damage in early-career musicians and non-musicians with normal hearing over a 2-year period. Participants completed an annual test battery consisting of pure tone audiometry, extended high-frequency hearing thresholds, distortion product otoacoustic emissions (DPOAEs), speech perception in noise, auditory brainstem responses, and self-report measures of tinnitus, hyperacusis, and hearing in background noise. Participants also completed the Noise Exposure Structured Interview to estimate cumulative noise exposure across the study period. Linear mixed models assessed changes over time. The longitudinal analysis comprised 64 early-career musicians (female n = 34; age range at T0 = 18-26 years) and 30 non-musicians (female n = 20; age range at T0 = 18-27 years). There were few longitudinal changes as a result of musicianship. Small improvements over time in some measures may be attributable to a practice/test-retest effect. Some measures (e.g., DPOAE indices of outer hair cell function) were associated with noise exposure at each time point, but did not show a significant change over time. A small proportion of participants reported a worsening of their tinnitus symptoms, which participants attributed to noise exposure, or not using hearing protection. Future longitudinal studies should attempt to capture the effects of noise exposure over a longer period, taken at several time points, for a precise measure of how hearing changes over time. Hearing conservation programmes for "at risk" individuals should closely monitor DPOAEs to detect early signs of noise-induced hearing loss when audiometric thresholds are clinically normal.

Sexual Dimorphism in the Functional Development of the Cochlear Amplifier in Humans

OBJECTIVES

Otoacoustic emissions, a byproduct of active cochlear mechanisms, exhibit a higher magnitude in females than in males. The relatively higher levels of androgen exposure in the male fetus are thought to cause this difference. Postnatally, the onset of puberty is also associated with the androgen surge in males. In this study, we investigated sexual dimorphism in age-related changes in stimulus-frequency otoacoustic emissions for children.

DESIGN

In a retrospective design, stimulus-frequency otoacoustic emissions were analyzed from a cross-sectional sample of 170 normal-hearing children (4 to 12 years) and 67 young adults. Wideband acoustic immittance and efferent inhibition measures were analyzed to determine the extent to which middle ear transmission and efferent inhibition can account for potential sex differences in stimulus-frequency otoacoustic emissions.

RESULTS

Male children showed a significant reduction in otoacoustic emission magnitudes with age, whereas female children did not show any such changes. Females showed higher stimulus-frequency otoacoustic emission magnitudes compared with males. However, the effect size of sex differences in young adults was larger compared with children. Unlike the otoacoustic emission magnitude, the noise floor did not show sexual dimorphism; however, it decreased with age. Neither the wideband absorbance nor efferent inhibition could account for the sex differences in stimulus-frequency otoacoustic emissions.

CONCLUSIONS

The cochlear-amplifier function remains robust in female children but diminishes in male children between 4 and 12 years of age. We carefully eliminated lifestyle, middle ear, and efferent factors to conclude that the androgen surge associated with puberty likely caused the observed masculinization of stimulus-frequency otoacoustic emissions in male children. These findings have significant theoretical consequences. The cochlea is considered mature at birth; however, the present findings highlight that functional cochlear maturation, as revealed by otoacoustic emissions, can be postnatally influenced by endogenous hormonal factors, at least in male children. Overall, work reported here demonstrates sexual dimorphism in the functional cochlear maturational processes during childhood.

Long-Term Variability of Distortion-Product Otoacoustic Emissions in Infants and Children and Its Relation to Pediatric Ototoxicity Monitoring

OBJECTIVE

Distortion-product otoacoustic emissions (DPOAEs) provide a rapid, noninvasive measure of outer hair cell damage associated with chemotherapy and are a key component of pediatric ototoxicity monitoring. Serial monitoring of DPOAE levels in reference to baseline measures is one method for detecting ototoxic damage. Interpreting DPOAE findings in this context requires that test-retest differences be considered in relation to normal variability, data which are lacking in children. This study sought to (1) characterize normal test-retest variability in DPOAE level over the long time periods reflective of pediatric chemotherapy regimens for a variety of childhood ages and f2 primary frequencies using common clinical instrumentation and stimulus parameters; (2) develop level-shift reference intervals; and (3) account for any age-related change in DPOAE level or measurement error that may occur as the auditory system undergoes maturational change early in life.

DESIGN

Serial DPOAE measurements were obtained in 38 healthy children (25 females and 13 males) with normal hearing and ranging in age from one month to 10 years at the initial (baseline) visit. On average, children were tested 5.2 times over an observation period of 6.5 months. Data were collected in the form of DP grams, in which DPOAE level was measured for f2 ranging from 1.4 to 10 kHz, using a fixed f2/f1 ratio of 1.22 and stimulus level of 65/55 dB SPL for L1/L2. Age effects on DPOAE level and measurement error were estimated using Bayesian regression of the longitudinal data. The raw and model-based distribution of DPOAE test-retest differences were characterized using means and standard error of the measurement for several ages and f2's.

RESULTS

DPOAE test-retest differences for the children in this study are at the high end of those previously observed in adults, as reflected in the associated shift reference intervals. Further, although we observe substantial child-specific variation in DPOAE level, the pattern of age-related changes is highly consistent across children. Across a wide range of f2's, DPOAE level decreases by 3 to 4 dB from 1 to 13 months of age followed by a more gradual decline of <1 dB/year. An f2 of 6 kHz shows the smallest decrease during the early rapid maturation period. DPOAE measurement error is fairly constant with age. It is 3 to 4 dB at most f2's and is greater (indicating poorer reliability) at 1.5, 8, and 10 kHz.

CONCLUSIONS

DPOAE level decreases with childhood age, with the greatest changes observed in the first year of life. Maturational effects during infancy and greater measurement error at very low and high f2's affect test-retest variability in children. An f2 of 6 kHz shows minimal maturation and measurement error, suggesting it may be an optimal sentinel frequency for ototoxicity monitoring in pediatric patients. Once validated with locally developed normative data, reference intervals provided herein could be used to determine screen fail criteria for serial monitoring using DPOAEs. Employing state-of-the-art calibration techniques might reduce variability, allowing for more sensitive screen fail criteria.

Hearing and Exposure to Music in Adolescents From Four Schools of Córdoba, Argentina

Purposes The aims of this study are (a) to characterize the hearing of adolescents from four schools of Córdoba, Argentina, through the analysis of conventional and extended high-frequency audiometric thresholds and otoacoustic emissions (OAEs) and (b) to analyze the association between the mentioned hearing tests and exposure to music. Method It was a cross-sectional correlational descriptive study. Hearing thresholds (250-16000 Hz), transient evoked OAEs, and distortion product OAEs were evaluated in 225 adolescents (450 ears) aged 14 and 15 years. The ears were split into two groups: Group 1 had thresholds ≤ 21 dB HL in all frequencies, and Group 2 had thresholds > 21 dB HL in at least one. Exposure to music was evaluated through a questionnaire. Results Statistically significant differences were found in both ears between Groups 1 and 2. A notch at 3000-6000 Hz was noted in both groups. Group 2 showed a progressive threshold increase from 9000 Hz. Amplitude decrease, negative values, absent distortion product OAEs, and transient evoked OAEs were noted even in Group 1. A statistically significant association between Groups 1 and 2 and the presence/absence of OAEs was observed in most frequencies. Ears with moderate or high exposure to music had greater hearing thresholds compared to ears with low exposure at most frequencies; this was more evident in Group 1. Regarding exposure to music and OAEs, no significant differences were found between the exposure categories. Conclusions The findings highlight the value of implementing hearing conservation programs in Argentina, analyzing hearing tests correlated with questionnaires about recreational noise exposure in order to detect vulnerable ears early.

Short-Term Reliability of Different Methods of Contralateral Suppression of Transient Evoked Otoacoustic Emission in Children and Adults

Purpose This study aimed to investigate the reliability of 3 methods to measure contralateral suppression of transient evoked otoacoustic emissions (TEOAEs) in children and adults. Method Contralateral suppression of TEOAEs was measured in 14 adults and 14 children using 3 methods with and without contralateral acoustic stimulus (CAS). Method-I having "2 s on-off" and Method-II having "10 s on-off" interleaved presentation of white noise. Method-III used "continuous presentation of white noise". Test-retest reliability was checked in adults without removing the probe (same-probe recording) and reinserting the probe (different-probe recording) and in children using a different-probe recording. Results The absolute suppression amplitude of TEOAEs was higher for "continuous noise," followed by "10 s on-off" and "2 s on-off" CAS. There was no significant effect of age across the 2 probe recordings, 3 methods of TEOAEs with and without CAS, and for the absolute suppression amplitude. Also, in adults, there was no significant difference between same-probe and different-probe recordings across the 3 methods. High internal consistency was observed on Cronbach's alpha (α > .9) for the 3 methods and 2 probe recordings. High agreement and correlation between the recordings for all 3 methods were seen using Bland-Altman plots and Pearson product-moment correlation coefficient. Conclusion The study demonstrated that highly reliable contralateral suppression of TEOAE can be measured using the 3 methods in adults and children. However, continuous presentation of CAS resulted in greater TEOAE suppression amplitude compared to interleaved presentation of CAS; hence, the former is recommended.

Assessment of short-term exposure to an ultrasonic rodent repellent device

The objectives of the present study were to investigate the acoustical properties of the very high frequencies and/or ultrasound signals produced by a repellent device and to investigate potential adverse factors as a result of short-term exposure to these signals. Potential adverse effects were evaluated perceptually with 25 young and 25 middle-aged persons, all with normal hearing thresholds, in a quiet room using different outcome measures, including a 15-item survey presented before and immediately after each condition. Spectral analyses showed that, besides emitting frequency modulated sounds in the expected frequency ranges, a faint but audible sound in the 4-5 kHz range was present. On average, a relatively short exposure to the sound produced by a repellent device did not lead to significant adverse effects. Yet, when the signal was perceived, as it was frequently for the younger population at the two lower frequencies settings (12-14 kHz, 25-25 kHz) and with 2 sources emitting, it was considered to be disturbing by several participants. Given the increasing usage of ultrasonic devices as well as the much longer exposure of high frequency and ultrasound in domestic usage, careful consideration and better guidelines are required, especially for those who are most sensitive to sound.

Hearing thresholds at high frequency in patients with cystic fibrosis: a systematic review

INTRODUCTION

High-frequency audiometry may contribute to the early detection of hearing loss caused by ototoxic medications. Many ototoxic drugs are widely used in the treatment of patients with cystic fibrosis. Early detection of hearing loss should allow known harmful drugs to be identified before the damage affects speech frequencies. The damage caused by ototoxicity is irreversible, resulting in important social and psychological consequences. In children, hearing loss, even when restricted to high frequencies, can affect the development of language.

OBJECTIVE

To investigate the efficacy and effectiveness of hearing monitoring through high-frequency audiometry in pediatric patients with cystic fibrosis.

METHODS

Electronic databases PubMed, MedLine, Web of Science and LILACS were searched, from January to November 2015. The selected studies included those in which high-frequency audiometry was performed in patients with cystic fibrosis, undergoing treatment with ototoxic drugs and published in Portuguese, English and Spanish. The GRADE system was chosen for the evaluation of the methodological quality of the articles.

RESULTS

During the search process carried out from January 2015 to November 2015, 512 publications were identified, of which 250 were found in PubMed, 118 in MedLine, 142 in Web of Science and 2 in LILACS. Of these, nine articles were selected.

CONCLUSION

The incidence of hearing loss was identified at high frequencies in cystic fibrosis patients without hearing complaints. It is assumed that high-frequency audiometry can be an early diagnostic method to be recommended for hearing investigation of patients at risk of ototoxicity.

Spontaneous otoacoustic emissions in schoolchildren

OBJECTIVE

Spontaneous otoacoustic emissions (SOAEs) are one of the least studied types of otoacoustic emissions (OAEs). The purpose of this study was twofold: first, to determine the prevalence of SOAEs in schoolchildren, and second to test whether there was dependence between the presence or absence of SOAEs in a subject and the corresponding level of their transiently evoked OAEs (TEOAEs).

METHODS

Measurements were made on a group of normally hearing children of age 7-13 years. A technique which detects synchronized SOAEs (SSOAEs) was used in which the response to repetitive clicks (12.5/s) was analyzed in the 60-80 ms time window following each click. The matching pursuit method was used to detect SSOAEs components above the noise in this window. For comparison, TEOAEs evoked by clicks (40/s) were obtained using the standard nonlinear protocol (20 ms time window).

RESULTS

The prevalence of SOAEs was 37%, and higher in females and right ears. There was an average of 2.3 SOAEs per emitting ear. TEOAE levels were higher for ears that had SOAEs and were lower for ears that did not have any SOAEs.

CONCLUSION

Although not all normal human have SOAEs, they appear to reflect an important aspect of cochlear function. Their presence is strongly related to elevated levels of TEOAEs which are routinely used in audiological tests.

Hearing thresholds, tinnitus, and headphone listening habits in nine-year-old children

Objective: Investigate hearing function and headphone listening habits in nine-year-old Swedish children. Design: A cross-sectional study was conducted and included otoscopy, tympanometry, pure-tone audiometry, and spontaneous otoacoustic emissions (SOAE). A questionnaire was used to evaluate headphone listening habits, tinnitus, and hyperacusis. Study sample: A total of 415 children aged nine years. Results: The prevalence of a hearing threshold ≥20 dB HL at one or several frequencies was 53%, and the hearing thresholds at 6 and 8 kHz were higher than those at the low and mid frequencies. SOAEs were observed in 35% of the children, and the prevalence of tinnitus was 5.3%. No significant relationship between SOAE and tinnitus was found. Pure-tone audiometry showed poorer hearing thresholds in children with tinnitus and in children who regularly listened with headphones. Conclusion: The present study of hearing, listening habits, and tinnitus in nine-year old children is, to our knowledge, the largest study so far. The main findings were that hearing thresholds in the right ear were poorer in children who used headphones than in children not using them, which could be interpreted as headphone listening may have negative consequences to children’s hearing. Children with tinnitus showed poorer hearing thresholds compared to children without tinnitus.

Tone burst evoked otoacoustic emissions in different age-groups of schoolchildren

INTRODUCTION

Otoacoustic emissions (OAEs) are believed to be good predictors of hearing status, particularly in the 1-4kHz range. However both click evoked OAEs (CEOAEs) and distortion product OAEs (DPOAEs) perform poorly at 0.5kHz. The present study investigates OAEs in the lower frequency range of 0.5-1kHz evoked by 0.5kHz tone bursts (TBOAEs) in schoolchildren and compares them with emissions evoked by clicks.

METHODS

Measurements were performed for two groups of normally hearing schoolchildren. Children from 1st grade (age 6-7 years) and children from 6th grade (age 11-12 years). Tympanometry, pure tone audiometry, and OAE measurements of CEAOEs, 0.5kHz TBOAEs, and spontaneous OAEs (SOAEs) were performed. Additionally, analysis by the matching pursuit method was conducted on CEOAEs and TBOAEs to assess their time-frequency (TF) properties.

RESULTS

For all subjects OAEs response levels and signal to noise ratios (SNRs) were calculated. As expected, CEOAE magnitudes were greatest over the range 1-4kHz, with a substantial decrease below 1kHz. Responses from the 0.5kHz TBOAEs were complementary in that the main components occurred between 0.5 and 1.4kHz. In younger children, TBOAEs had SNRs 4-8dB smaller in the 0.5-1.4kHz range. In addition, CEOAEs had lower SNRs in the 0.7-1.4kHz range, by 3-5dB. TBOAEs in younger children had maximum SNRs shifted toward 1-1.4kHz, whereas in older children it was more clearly around 1kHz. The differences in response levels were less evident. The presence of SOAEs appreciably influenced both CEOAEs and TBOAEs, and TF properties of both OAEs did not differ significantly between grades.

CONCLUSION

TBOAEs evoked at 0.5kHz can provide additional information about frequencies below 1kHz, a range over which CEOAEs usually have very low amplitudes. The main difference between the two age groups was that in older children CEOAEs and 0.5kHz TBOAEs had higher SNRs at 0.5-1.4kHz. Additionally, for ears with SOAEs, 0.5kHz TBOAEs had higher response levels and SNRs similar to CEOAEs.

Distortion-product otoacoustic emissions at ultra-high frequencies in parents of individuals with autosomal recessive hearing loss

Purpose: To evaluate the cochlear function of parents of individuals with autosomal recessive gene Gap Junction Protein Beta-2 hearing loss by ultra-high frequencies distortion-product otoacoustic emissions (DPOAEs), compared with responses of a control group matched for age and gender. Methods: We studied 56 subjects aged from 20 to 58 years, divided into two groups. The study group comprised 28 parents of hearing-impaired patients due to autosomal recessive inheritance, 14 females aged 20.0-55.0 years (mean 32.8 years) and 14 males aged 20.0-58.0 years (mean 35.2 years). Control group was composed of normal hearing individuals, 14 males and 14 females age-matched to the study group. The subjects underwent tests for audiometry, tympanometry, and DPOAE in the frequency range of 9.000-16.000 Hz. Results: We found 64.3% of normal results of DPOAE in the study group compared to 91.1% in the control. There were significant differences between groups in the ears and DPOAE responses, and the mean level of response was in 10 dBNPS in study group and 14 dBNPS in the control. The Pearson's correlation between age and DPOAE in ultra-high frequencies showed no statistical significance. Conclusion: DPOAE at ultra-high frequencies were able to identify individuals from both groups, suggesting that heterozygous individuals for the Gap Junction Protein Beta-2 gene mutation may have damage to the cochlear function before clinical manifestation in audiometry.

Low-frequency otoacoustic emissions in schoolchildren measured by two commercial devices

OBJECTIVE

Click evoked otoacoustic emissions in children are known to be good indicators of hearing function when used in the frequency range 1.5-4 kHz. Using two commercial devices, the present study investigates the usefulness of responses in the lower frequency range of 0.5-1 kHz evoked by 0.5 kHz tone bursts.

METHODS

Otoacoustic emissions (OAEs) were recorded from the ears of 37 schoolchildren (age 12-13 years). OAE measurements were then made using two devices: the ILO 292 (Otodynamics) and the HearId (Mimosa Acoustics). Each device was used for two measurements: first with a standard click stimulus at 80 dB pSPL (CEOAEs) and a second using a 0.5 kHz tone burst at 80 dB pSPL (TBOAEs). Pure tone audiometry and tympanometry were also conducted. Half-octave-band values of OAE signal to noise ratios (SNRs) and response levels were used to assess statistical differences.

RESULTS

Both devices provided similar SNR results for click and tone burst stimuli, although the ILO device generated slightly higher response levels for clicks. For the 0.5 kHz tone bursts, both devices evoked very weak responses at 0.5 kHz and the peak response occurred at 0.7-1 kHz. Generally, CEOAE SNRs were about 10 dB in the 1-4 kHz range, while SNRs for 0.5 kHz TBOAEs were about 10 dB at 0.7-1 kHz.

CONCLUSIONS

0.5 kHz TBOAEs could be measured in children as effectively as CEOAEs. They can provide additional information about the 0.7-1 kHz frequency range, a range over which CEOAEs do not usually contain responses above the noise floor. The main difficulty was that the maxima of the 0.5 kHz TBOAEs occurred at frequencies of 0.7-1 kHz, probably because of spectral splatter from the short tone burst stimulus and from rapidly falling responses of the cochlea and the recording system at low frequencies.

Hearing function in heterozygous carriers of a pathogenic GJB2 gene mutation

The most frequent hereditary hearing loss is caused by mutations in the GJB2 gene coding for the gap junction beta 2 protein Connexin 26 (Cx26). In contrast to many studies performed in patients with bi-allelic mutations, audiometric studies on heterozygotes are sparse and often contradictory. To evaluate hearing function in heterozygous carriers of the GJB2 c.35delG mutation, audiometry over the extended frequency range and the recording of otoacoustic emissions (OAEs), i.e., transient-evoked OAEs (TEOAEs) and distortion product OAEs (DPOAEs), were performed in a group of parents and grandparents of deaf children homozygous for the GJB2 c.35delG mutation. The comparison of audiograms between control and heterozygous subjects was enabled using audiogram normalization for age and sex. Hearing loss, estimated with this procedure, was found to be significantly larger in GJB2 c.35delG heterozygous females in comparison with controls for the frequencies of 8-16 kHz; the deterioration of hearing in heterozygous men in comparison with controls was not statistically significant. A comparison of TEOAE responses and DPOAE levels between GJB2 c.35delG heterozygotes and controls did not reveal any significant differences. The results prove the importance of using audiometry over the extended frequency range and audiogram normalization for age and sex to detect minor hearing impairments, even in a relatively small group of subjects of different ages.

Chirp-evoked otoacoustic emissions in children

OBJECTIVE

The purpose of the study was to investigate the properties of otoacoustic emissions (OAEs) evoked by chirp stimuli and compare them with standard click-evoked OAEs. Differences between evoked OAEs in children with and without spontaneous otoacoustic emissions (SOAEs) were also assessed.

METHODS

OAEs were first recorded from 54 children (age 4-10 years) in a screening setup. In each ear five OAE measurements were made using two types of chirps (7.5 ms and 10.5 ms) at around 70 dB pSPL; clicks at 70 and 80 dB pSPL; and a standard synchronized SOAE stimulation protocol. Tympanometry was also conducted. Pass/refer criteria based on signal to noise ratios (SNRs) were applied to all OAEs. Pass/refer rates from all methods (OAEs evoked by chirps and clicks, and tympanometry) were compared. Additionally, half-octave-band values of OAE SNRs and response levels were used to assess statistical differences.

RESULTS

Chirp-evoked OAEs generated a similar number of passes to click-evoked OAEs when the same level of stimulus was used. When using lower stimulus levels, both chirp- and click-evoked OAEs diagnosed nearly all ears that failed tympanometry. The response levels and SNRs of OAEs evoked by clicks and chirps were very similar. The highest response levels were in the 1.4 kHz half-octave band. The SNRs for ears with SOAEs were highest at 1.4 kHz, whereas they were at 4 kHz for ears without SOAEs. Both response levels and SNRs were higher by about 5 dB for ears with SOAEs than ears without SOAEs. Also all ears with SOAEs generated a pass result in screening, while ears without SOAEs gave a pass less frequently (at least 30% fewer cases).

CONCLUSIONS

The results suggest that performance of chirp-evoked OAEs for screening purposes is similar to click-evoked OAEs when the same stimulus level is applied. OAEs evoked with lower stimulus levels (70 vs. 80 dB pSPL) are more sensitive to middle ear pathology. The presence of SOAEs significantly influences the pass rates of OAEs evoked by chirps and clicks.

Behavioral hearing thresholds between 0.125 and 20 kHz using depth-compensated ear simulator calibration

OBJECTIVES

The purpose of this study was to obtain behavioral hearing thresholds for frequencies between 0.125 and 20 kHz from a large population between 10 and 65 yr old using a clinically feasible calibration method expected to compensate well for variations in the distance between the eardrum and an insert-type sound source. Previous reports of hearing thresholds in the extended high frequencies (>8 kHz) have either used calibration techniques known to be inaccurate or specialized equipment not suitable for clinical use.

DESIGN

Hearing thresholds were measured from 352 human subjects between 10 and 65 yr old having clinically normal-hearing thresholds (<20 dB HL) up to 4 kHz. An otoacoustic emission probe fitted with custom sound sources was used, and the stimulus levels individually tailored on the basis of an estimate of the insertion depth of the measurement probe. The calibrated stimulus levels were determined on the basis of measurements made at various depths of insertion in a standard ear simulator. Threshold values were obtained for 21 frequencies between 0.125 and 20 kHz using a modified Békésy technique. Forty-six of the subjects returned for a second measurement months later from the initial evaluation.

RESULTS

In agreement with previous reports, hearing thresholds at extended high frequencies were found to be sensitive to age-related changes in auditory function. In contrast with previous reports, no gender differences were found in average hearing thresholds at most evaluated frequencies. Two aging processes, one faster than the other in time scale, seem to influence hearing thresholds in different frequency ranges. The standard deviation (SD) of test-retest threshold difference for all evaluated frequencies was 5 to 10 dB, comparable to that reported in the literature for similar measurement techniques but smaller than that observed for data obtained using the standard clinical procedure.

CONCLUSIONS

The depth-compensated ear simulator-based calibration method and the modified Békésy technique allow reliable measurement of hearing thresholds over the entire frequency range of human hearing. Hearing thresholds at the extended high frequencies are sensitive to aging and reveal subtle differences, which are not evident in the frequency range evaluated regularly (≤8 kHz). Previously reported gender-related differences in hearing thresholds may be related to ear-canal acoustics and the calibration procedure and not because of differences in hearing sensitivity.

Clinical evaluation of cochlear hearing status in dogs using evoked otoacoustic emissions

OBJECTIVES

Evoked otoacoustic emission testing is the preferred test in human patients for sensorineural deafness screening in neonates and cochlear outer hair cell function monitoring in adults. This study evaluated evoked otoacoustic emission testing for cochlear function assessment in dogs within a clinical setting.

METHODS

Two populations of anaesthetised dogs were included. In group 1 the evoked otoacoustic emission response was compared to the brainstem auditory evoked response in 10 dogs having hearing assessment. Group 2 comprised 43 presumed normal dogs, in which the suitability of two types of evoked otoacoustic emissions, transient-evoked and distortion product otoacoustic emissions, were evaluated (brainstem auditory evoked response was not performed in this group).

RESULTS

Valid transient-evoked otoacoustic emission and distortion-product otoacoustic emission responses were successfully recorded within the clinical setting and correctly identified deaf and hearing ears. Within presumed healthy dogs, normal otoacoustic emission response was demonstrated in more than 80% of dogs using a single, short distortion-product otoacoustic emission run and in 78% of dogs with valid transient-evoked otoacoustic emission responses using a series of three repeated transient-evoked otoacoustic emission short runs.

CLINICAL SIGNIFICANCE

Transient-evoked otoacoustic emission and distortion-product otoacoustic emission testing provided a rapid, non-invasive frequency-specific assessment of cochlear function. Transient-evoked otoacoustic emission and distortion product otoacoustic emission testing is suitable as a screening procedure to detect loss of cochlear function in dogs, although further investigation is needed.

Effect of age on click-evoked otoacoustic emission: A systematic review

OBJECTIVE:

The aims of this study were to investigate the changes of the total intensity of transient evoked otoacoustic emission (TEOAE) and signal-to-noise ratio in various frequency bands as a function of aging, and to explore the role of age-related decline of cochlear outer hair cells.

DATA SOURCES:

The literature was searched using the PubMed database using ‘transient-evoked otoacoustic emissions’ as a keyword. Articles were limited as follows: Species was ‘Humans’; languages were ‘English and Chinese’; publication date between 1990-01-01 and 2010-12-31. The references of the found were also searched to obtain additional articles.

DATA SELECTION:

Inclusion criteria: (1) Articles should involve the total TEOAE level or signal-to-noise ratio. (2) The measurement and analysis system used was Otodynamics ILO analysis system (ILO88, ILO92, ILO96 or ILO292). (3) Studies involved groups of greater than 10 subjects and TEOAE results were from normally hearing ears. (4) If more papers from the same author or laboratory analyzed the same subjects, only one was used.

MAIN OUTCOME MEASURES:

The correlations of the age scale with the total level and signal-to-noise ratio of TEOAE was determined, respectively.

RESULTS:

(1) TEOAE total level gradually increased until 2 months of age, and then decreased with increasing age. Significant negative correlations between total TEOAE level and age were found (r = –0.885, P = 0.000). (2) The most rapid decrease of TEOAE amplitude occurred at 1 year old. The total TEOAE level decreased about 4.25 dB SPL between 2 months to 1 year old, then about 0.26–0.52 dB SPL from 1 year to 10 years old, about 0.23 dB SPL from 11 years to 25 years old, and about 0.14 dB SPL from 26 years to 60 years old. (3) The signal-to-noise ratio in the frequency bands centered at 1.5, 2, 3 and 4 kHz decreased with increasing age after 2 months of age. Significant negative correlations between the signal-to-noise ratio and age were found for frequency bands ranging from 1.5 kHz to 4 kHz, with the highest correlations at 4 kHz (r = –0.890, P < 0.01), then at 3 kHz (r = –0.889, P < 0.01), at 2 kHz (r = –0.850, P < 0.01) and at 1.5 kHz (r = –0.705, P < 0.05). Conversely, a positive correlation between the signal-to-noise ratio centered at 1 kHz and age was found, but was not statistically significant (r = 0.298, P = 0.374).

CONCLUSION:

The total TEOAE response level decreased with increasing age after the first 2 months of age. The signal-to-noise ratio also decreased with increasing age in frequency bands above 1.5 kHz. The signal-to-noise ratio in higher frequencies decreased faster than in lower frequencies, leading to the maximum signal-to-noise ratio shift form 3.2–4.0 kHz in neonates to 1.5 kHz in adults, and further decreasing the total TEOAE response level. The age-related TEOAE spectrum peak shift is most likely because the outer hair cells functioning in higher frequencies are more prone to damage than those for lower frequencies.

A report of extended high frequency audiometry thresholds in school-age children with no hearing complaints

The aim of the study was to establish the extended high frequency thresholds (EHF) of school-age children with no hearing complaints. The study was conducted on 50 children aged 8 to 12 years with pure tone thresholds (0.5, 1 and 2 kHz) of 15 dB HL or less, with normal speech discrimination and tympanometry and with the presence of contralateral acoustic reflexes of 0.5, 1, 2 and 4 kHz. The children were tested for EHF at frequencies of 9, 10, 11.2, 12.5, 14 and 16 kHz. No significant differences were found between the right and left ear for female and male groups. The results allowed us to group the children into a single sample with mean thresholds (dB) of 8.6 (9 kHz), 6.2 (10 kHz), 8.2 (11.2 kHz), 7.1 (12.5 kHz), 0.4 (14 kHz), and -3.6 (16 kHz). We conclude that, for school-age children, the extended EHF below 15 dBHL could be used as an indication of normal hearing sensitivity.

A report of extended high frequency audiometry thresholds in school-age children with no hearing complaints

The aim of the study was to establish the extended high frequency thresholds (EHF) of school-age children with no hearing complaints. The study was conducted on 50 children aged 8 to 12 years with pure tone thresholds (0.5, 1 and 2 kHz) of 15 dB HL or less, with normal speech discrimination and tympanometry and with the presence of contralateral acoustic reflexes of 0.5, 1, 2 and 4 kHz. The children were tested for EHF at frequencies of 9, 10, 11.2, 12.5, 14 and 16 kHz. No significant differences were found between the right and left ear for female and male groups. The results allowed us to group the children into a single sample with mean thresholds (dB) of 8.6 (9 kHz), 6.2 (10 kHz), 8.2 (11.2 kHz), 7.1 (12.5 kHz), 0.4 (14 kHz), and -3.6 (16 kHz). We conclude that, for school-age children, the extended EHF below 15 dBHL could be used as an indication of normal hearing sensitivity.

Prevalence and audiological features in carriers of GJB2 mutations, c.35delG and c.101T>C (p.M34T), in a UK population study

OBJECTIVES

To determine the carrier rate of the GJB2 mutation c.35delG and c.101T>C in a UK population study; to determine whether carriers of the mutation had worse hearing or otoacoustic emissions compared to non-carriers.

DESIGN

Prospective cohort study.

SETTING

University of Bristol, UK.

PARTICIPANTS

Children in the Avon Longitudinal Study of Parents and Children. 9202 were successfully genotyped for the c.35delG mutation and c.101>T and classified as either carriers or non-carriers.

OUTCOME MEASURES

Hearing thresholds at age 7, 9 and 11 years and otoacoustic emissions at age 9 and 11.

RESULTS

The carrier frequency of the c.35delG mutation was 1.36% (95% CI 1.13 to 1.62) and c.101T>C was 2.69% (95% CI 2.37 to 3.05). Carriers of c.35delG and c.101T>C had worse hearing than non-carriers at the extra-high frequency of 16 kHz. The mean difference in hearing at age 7 for the c.35delG mutation was 8.53 dB (95% CI 2.99, 14.07) and 12.57 dB at age 9 (95% CI 8.10, 17.04). The mean difference for c.101T>C at age 7 was 3.25 dB (95% CI -0.25 to 6.75) and 7.61 dB (95% CI 4.26 to 10.96) at age 9. Otoacoustic emissions were smaller in the c.35delG mutation carrier group: at 4 kHz the mean difference was -4.95 dB (95% CI -6.70 to -3.21) at age 9 and -3.94 dB (95% CI -5.78 to -2.10) at age 11. There was weak evidence for differences in otoacoustic emissions amplitude for c.101T>C carriers.

CONCLUSION

Carriers of the c.35delG mutation and c.101T>C have worse extra-high-frequency hearing than non-carriers. This may be a predictor for changes in lower-frequency hearing in adulthood. The milder effects observed in carriers of c.101T>C are in keeping with its classification as a mutation causing mild/moderate hearing loss in homozygosity or compound heterozygosity.

Aminoglycoside antibiotics cochleotoxicity in paediatric cystic fibrosis (CF) patients: A study using extended high-frequency audiometry and distortion product otoacoustic emissions

Despite known ototoxic effects of aminoglycoside (AG) antibiotics, audiological assessment is not routinely undertaken in UK CF patients. Consequently, the incidence of hearing loss is not well established.

OBJECTIVE

To document the incidence of hearing loss in cystic fibrosis (CF) children.

DESIGN

Hearing function of 45 children from Great Ormond Street Hospital was assessed using pure-tone audiometry up to 20kHz and DPOAEs up to 8kHz.

STUDY SAMPLE

39/45 of participants had received intravenous (IV) AGs, 23 of which received repeated IV AGs every 3 months.

RESULTS

In this high exposure group, 8 (21%) had clear signs of ototoxicity; average 8-20kHz thresholds were elevated by ∼50dB and DPOAE amplitudes were >10dB lower at f2 3.2-6.3 kHz. The remaining 31/39 (79%) of AG exposed patients had normal, even exceptionally good hearing. The 21% incidence of ototoxicity we observed is substantial and higher than previously reported. However, our finding of normal hearing in children with equal AG exposure strongly suggests that other unknown factors, possibly genetic susceptibility, influence this outcome.

CONCLUSIONS

We recommend comparable auditory testing in all CF patients with high AG exposures. Genetic analysis may help explain the dichotomy in response to AGs found.

Auditory measurements in parents of individuals with autosomal recessive hearing loss

BACKGROUND

Audiological evaluation of parents of individuals with autosomal recessive hearing loss.

AIM

To study the audiological profile of parents of individuals with autosomal recessive hearing loss, inferred by family history or by molecular tests that detected heterozygous mutations in the GJB2 gene. This gene codes Connexin 26.

METHOD

Participants were 36 subjects, ranging between 30 and 60 years, who were divided into two groups: a control group composed by individuals without auditory complaints and without family history of hearing loss, and a research group composed by heterozygous parents of individuals with autosomal recessive hearing loss or heterozygous for connexin 26 mutations. All subjects underwent pure tone audiometry (0.25 to 8 kHz), high frequencies audiometry (9 to 20 kHz) and distortion product otoacoustic emissions (DPOAE).

RESULTS

There were significant differences between the groups when considering the amplitude of DPOAE in the frequencies of 1001 and 1501 Hz. Amplitude was higher in the control group. There was no significant difference between the groups for pure tone thresholds from 0.25 to 20 KHz.

CONCLUSION

The DPOAE were more effective, in comparison to the pure tone audiometry, to detect auditory differences between the groups. More studies of this type are necessary to confirm the observed results.

Estudo das emissões otoacústicas - produto de distorção durante a prática esportiva associada à exposição à música

OBJETIVO: estudar a audição dos alunos de uma academia de ginástica durante o exercício físico, analisando os resultados das emissões otoacústicas - produto de distorção (EOAPD), antes e após a exposição à música eletronicamente amplificada. MÉTODOS: foi aplicado um questionário em 20 indivíduos, sendo os mesmos avaliados por meio das EOAPD, antes e após a execução do exercício físico e exposição à música. RESULTADOS: uma elevada porcentagem de exposições extra-ocupacionais e de lazer (65%) foi encontrada ao analisar as queixas. Observou-se que 40% dos alunos de academia de ginástica apresentaram dores de cabeça e insônia; sete, intolerância para sons intensos; cinco, plenitude auricular e irritabilidade; cinco, nervosismo; quatro, tontura; e três relataram apresentar zumbidos após as aulas. No teste de EOPD, houve presença de respostas em 100% das orelhas testadas no momento 1 (M1), porém, no momento 2 (M2), houve presença de resposta em 75%. As frequências que apresentaram maior percentual de falhas no momento 2 (M2) foram 3KHz, 4KHz e 5 KHz. CONCLUSÃO: exercício físico associado a elevados níveis de pressão sonora de música provocam alterações nas EOA-PD, principalmente nas frequências de 3000Hz, 4000Hz e 5000Hz. Desse modo, alunos de academia de ginástica que ficam expostos à música eletronicamente amplificada podem estar prejudicando a audição. Há necessidade, portanto, das academias avaliarem as condições acústicas de suas salas de aulas, a partir da análise de profissionais especializados no intuito de verificarem os níveis sonoros, desse modo, observando se estes (NPS) estão compatíveis com os valores recomendados pela lei.

Frequency distribution of synchronized spontaneous otoacoustic emissions showing sex-dependent differences and asymmetry between ears in 2- to 4-day-old neonates

OBJECTIVE

The mature pattern of frequency distribution of synchronized spontaneous otoacoustic emissions (SSOAEs) has been reported to be bimodal in adults and children between 5 and 11 years of age; however, little is known about the distribution in neonates between 2 and 4 days after birth. Furthermore, overall differences in frequency distribution resulting from difference in sex and asymmetry between ears have not been carefully examined. The aim of this study is to determine the frequency distribution of SSOAEs in neonates at 2 to 4 days of age, evaluate the maturity of the pattern of distribution in this age group, and to evaluate the effects of differences in sex and asymmetry between left and right ears on the frequency distribution.

METHODS

We evaluated 224 ears in 112 newborns (59 girls, 53 boys) whose ages ranged from 2 to 4 days. The SSOAEs were measured using ILO96.

RESULTS

Most of the SSOAEs (86.5%) appeared at frequencies between 1.01 and 4.50 kHz. The overall frequency distribution of the SSOAEs showed a 'peak-valley-peak' pattern when plotted. Two peaks with maxima at 1.41-1.60 and 3.01-3.20 kHz were separated by a valley with a minimum at 2.41-2.60 kHz. Both girls and boys had approximate monomodal patterns in the distribution of SSOAEs. Significant sex-dependent differences were noted with more SSOAEs at the lower frequencies (<or=2 kHz) in boys (46.1%) than in girls (32.0%) (P<0.05) and more SSOAEs at the higher frequencies (2.51- 4.50 kHz) in girls (50.9%) than in boys (37.5%) (P<0.05). Both the right and left ears showed the 'peak-valley-peak' pattern that was similar to the overall distribution pattern. But, compared with the peaks measured in the left ears at 1.01-1.50 and 3.01-3.50 kHz, the peaks of the right ears at 1.51-2.00 and 2.51-3.00 kHz were much closer to the valley.

CONCLUSIONS

The overall distribution of frequency of SSOAEs in 2- to 4-day-old neonates had the similar mature 'peak-valley-peak' distribution pattern seen in adults. Significant sex-dependent differences of the SSOAEs frequency distributions have been found. However, only slight ear asymmetries of the SSOAEs frequency distributions can observed in this age group.