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

Serum Prestin Level May Increase Following Music Exposure That Induces Temporary Threshold Shifts: A Pilot Study

OBJECTIVES

To determine if blood prestin level changes after exposure to music at high sound pressure levels, and if this change is associated with temporary threshold shift (TTS) and/or changes in distortion product (DP) amplitude.

DESIGN

Participants were exposed to pop-rock music at 100 dBA for 15 min monaurally through headphones. Pure-tone audiometry, DP amplitude, and blood prestin level were measured before and after exposure.

RESULTS

Fourteen adults (9 women; age range: 20 to 54 years, median age = 31 [Interquartile ratio = 6.75]) with normal hearing were included in the study. Mean prestin level increased shortly after exposure to music, then returned to baseline within 1 week, although this trend was not observed in all participants. All participants presented TTS or a decrease in DP amplitude in at least one frequency after music exposure. There was a statistically significant average threshold elevation at 4 min postexposure. Statistically significant DP amplitude shifts were observed at 4 and 6 kHz, 2 min following exposure. Mean baseline serum prestin level (mean: 140.00 pg/mL, 95% confidence interval (CI): 125.92 to 154.07) progressively increased following music exposure, reaching a maximum at 2 hr (mean: 158.29 pg/mL, 95% CI: 130.42 to 186.66) and returned to preexposure level at 1 week (mean: 139.18 pg/mL, 95% CI: 114.69 to 163.68). However, after correction for multiple comparisons, mean prestin level showed no statistically significant increase from baseline at any timepoint. No correlation between maximum blood prestin level change and average TTS or distortion product otoacoustic emission amplitude shift was found. However, in an exploratory analysis, TTS at 6 kHz (the frequency at which maximum TTS occurred) decreased significantly as baseline blood prestin level increased.

CONCLUSIONS

The results suggest that blood prestin level may change after exposure to music at high sound pressure levels, although statistical significance was not reached in this relatively small sample after correction. Baseline serum prestin level may also predict the degree of TTS. These findings thus suggest that the role of baseline serum prestin level as a proxy marker of cochlear susceptibility to intense music exposure should be further explored.

Development and Validation of an Efficient and Safe Loud Music Exposure Paradigm

PURPOSE

The purpose of this study was to develop a time-efficient music exposure and testing paradigm that safely creates temporary cochlear dysfunction that could be used in future temporary threshold shift (TTS) studies.

METHOD

A 30-min audio compilation of pop rock music tracks was created. Adult volunteers with normal hearing were then exposed to this music material monaurally through headphones for 30 min at 97 dBA or 15 min at 100 dBA. Levels were measured from the ear of a manikin and are considered to provide an equivalent daily noise dose based on a 3-dB exchange. We assessed the changes in their hearing, by means of distortion product otoacoustic emission (DPOAE) testing, and standard and extended high-frequency pure-tone audiometry before and after exposure. There were 17 volunteers in total. In the first trial, eight volunteers (four females; Mdnage = 31 years [interquartile range, IQR = 4.25]) were included. Although TTS was observed in all eight participants for at least one frequency, a large variation in affected frequencies was observed. To address this issue, the audio material was further remastered to adjust levels across the different frequency bands. Fourteen adults (nine newly recruited and five from the first trial; seven females; Mdnage = 31 years [IQR = 5]) were exposed to the new material.

RESULTS

All but two of 17 participants presented clinically significant TTS or decrease in DPOAE amplitude in at least one frequency. Statistically significant average TTS of 7.43 dB was observed at 6 kHz. There were statistically significant average DPOAE amplitude shifts of -2.55 dB at 4 kHz, -4.97 dB at 6 kHz, and -3.14 dB at 8 kHz. No participant presented permanent threshold shift.

CONCLUSIONS

A monaural music paradigm was developed and shown to induce statistically significant TTS and DPOAE amplitude shifts, without evidence of permanent loss. This realistic and time-efficient paradigm may be considered a viable option for experimental studies of temporary music-induced hearing loss.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.25016471.

Associations Between Recreational Noise Exposure and Hearing Function in Adolescents and Young Adults: A Systematic Review

PURPOSE

There is an increasing concern regarding hazardous recreational noise exposure among adolescents and young adults. Daily exposure to loud sound levels over a long period of time can increase the risk of noise-induced hearing loss. The full extent of the impact of recreational noise on hearing is not yet fully understood. The purpose of this review was to synthesize research that investigated hearing function in relation to recreational noise exposure in adolescents and young adults.

METHOD

A systematic literature search of five databases covering the years 2000-2023 was performed. The articles included investigated audiological measurements of hearing function in relation to recreational noise exposure.

RESULTS

Four hundred sixty records were identified, of which 20 met the inclusion criteria and were included in the results. This review showed that although some recreational noise activities can be potentially harmful, there is an unclear relationship between exposure and outcome. Some findings indicated hearing threshold shifts or reduced otoacoustic emission amplitudes after recreational noise exposure, but most changes were short term and in the extended high-frequency range.

CONCLUSIONS

There seemed to be inconsistencies regarding the utilization of methods of measuring exposure and outcome between studies. This might be one reason for the differing results in studies on the reported impact on hearing function from recreational noise exposure. To draw more certain conclusions about long-term effects, there is a need for longitudinal research that utilizes sound level measurements to assess low and high degrees of recreational noise exposure in relation to hearing function.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.25114193.

Robust estimation of synchronized spontaneous otoacoustic emission via singular value decomposition and optimal shrinkage

We investigate matrix signal processing techniques for estimating synchronized spontaneous otoacoustic emission (OAE) in noise. Responses to repeated clicks are first stored in a matrix, and singular value decomposition is either applied in the time domain or the frequency domain after constructing a Hankel matrix at every frequency. The singular values are subject to optimal shrinkage (OS) which maximizes the signal-to-noise ratio. Human OAE data were analyzed, and the Hankel matrix method outperforms the time-domain OS method in synchronized spontaneous otoacoustic emission estimation, but not in the estimation of transient-evoked otoacoustic emission. Reasons for the performance discrepancy are discussed.

Identifying Health-Related Conditions Associated with Tinnitus in Young Adults

OBJECTIVE

The present study investigated the epidemic of tinnitus in college-aged young adults. Our first objective was to identify health conditions associated with tinnitus in young adults. The second objective was to evaluate the predictive utility of some known risk factors.

STUDY DESIGN

A cross-sectional design was used to investigate the prevalence and risk factors for tinnitus.

SETTING

A questionnaire was distributed, reaching out to a large college-aged population. A total of 2258 young adults aged 18-30 years were recruited from April 2021 to February 2022.

INTERVENTIONS

A questionnaire was administered to investigate the epidemiology of tinnitus in a population of college-aged young adults.

RESULTS

About 17.7% of young adults reported bothersome tinnitus perception lasting for ≥5 min in the last 12 months. The prevalence of chronic tinnitus (bothersome tinnitus for ≥1 year) and acute tinnitus (bothersome tinnitus for <1 year) was 10.6% and 7.1%, respectively. About 19% of the study sample reported at least one health condition. Individuals reporting head injury, hypertension, heart disease, scarlet fever, and malaria showed significantly higher odds of reporting chronic tinnitus. Meningitis and self-reported hearing loss showed significant associations with bothersome tinnitus. The prevalence of chronic tinnitus was significantly higher in males reporting high noise exposure, a positive history of reoccurring ear infections, European ethnic background, and a positive health history. Risk modeling showed that noise exposure was the most important risk factor for chronic tinnitus, followed by sex, reoccurring ear infections, and a history of any health condition. A positive history of COVID-19 and self-reported severity showed no association with tinnitus. Individuals reporting reoccurring ear infections showed a significantly higher prevalence of COVID-19.

CONCLUSIONS

While young adults with health conditions are at a higher risk of reporting tinnitus, the predictive utility of a positive health history remains relatively low, possibly due to weak associations between health conditions and tinnitus. Noise, male sex, reoccurring ear infections, European ethnicity, and a positive health history revealed higher odds of reporting chronic tinnitus than their counterparts. These risk factors collectively explained about 16% variability in chronic tinnitus, which highlights the need for identifying other risk factors for chronic tinnitus in young adults.

A Smartphone Application and Education Program for Hearing Health Promotion in High School Teenagers

OBJECTIVES

To assess knowledge retention after video-based hearing health education and measure headphone listening behavior change using a novel smartphone application.

METHODS

In this prospective longitudinal study, students participated in video-based hearing health education and hearing screening sessions. Hearing health knowledge was assessed in students and parents after 6 weeks. A novel smartphone application was created to measure daily noise exposure based on volume settings with headphone use and to display the National Institute for Occupational Safety and Health (NIOSH) noise doses with alerts for cumulative daily doses nearing the maximum.

RESULTS

Seventy-six teenage students and parents participated. Eighty three percent of participants identified as a racial or ethnic minority and 66% were of low-income socioeconomic status. Hearing health knowledge was retained in students 6 weeks after education and parents' knowledge improved from baseline. The smartphone app was installed on 12 student phones, and 25% of days monitored exhibited noise doses that exceeded the NIOSH maximum. App use for at least 10 days by nine students showed a significant reduction in average daily noise dose and time spent at the highest volume settings during the second-half of app use.

CONCLUSIONS

Video-based hearing health education with knowledge question reinforcement was associated with knowledge retention in students and improved parental attitudes and knowledge about hearing conservation. A smartphone app with a real-time display of headphone cumulative noise exposure dose identified at-risk students. The integration of hearing health education, hearing screening, and digital health tools has promised to promote positive behavior changes for long-term hearing conservation.

LEVEL OF EVIDENCE

4 Laryngoscope, 2022.

Suprathreshold Auditory Measures for Detecting Early-Stage Noise-Induced Hearing Loss in Young Adults

BACKGROUND

Over 1 billion young adults are at risk for developing noise-induced hearing loss (NIHL) due to their habit of listening to music at loud levels. The gold standard for detecting NIHL is the audiometric notch around 3,000 to 6,000 Hz observed in pure tone audiogram. However, recent studies suggested that suprathreshold auditory measures might be more sensitive to detect early-stage NIHL in young adults.

PURPOSE

The present study compared suprathreshold measures in individuals with high and low noise exposure backgrounds (NEBs). We hypothesized that individuals with high NEB would exhibit reduced performance on suprathreshold measures than those with low NEB.

STUDY SAMPLE

An initial sample of 100 English-speaking healthy adults (18-35 years; females = 70) was obtained from five university classes. We identified 15 participants with the lowest NEB scores (10 females) and 15 participants with the highest NEB scores (10 females). We selected a sample of healthy young adults with no history of middle ear infection, and those in the low NEB group were selected with no history of impulse noise exposure.

DATA COLLECTION AND ANALYSIS

The study included conventional audiometry, extended high-frequency audiometry, middle ear muscle reflex (MEMR) thresholds, distortion-product otoacoustic emissions (DPOAEs), QuickSIN, and suprathreshold auditory brainstem response (ABR) measures. We used independent sample t-tests, correlation coefficients, and linear mixed model analysis to compare the audiometric measures between the NEB groups.

RESULTS

The prevalence of audiometric notch was low in the study sample, even for individuals with high NEB. We found that: (1) individuals with high NEB revealed significantly reduced QuickSIN performance than those with low NEB; (2) music exposure via earphone revealed a significant association with QuickSIN; (3) individuals with high NEB revealed significantly reduced DPOAEs and ABR wave I amplitude compared with individuals with low NEB; (4) MEMR and ABR latency measures showed a modest association with NEB; and (5) audiometric thresholds across the frequency range did not show statistically significant association with NEB.

CONCLUSION

Our results suggest that young adults with high NEB might exhibit impaired peripheral neural coding deficits leading to reduced speech-in-noise (SIN) performance despite clinically normal hearing thresholds. SIN measures might be more sensitive than audiometric notch for detecting early-stage NIHL in young adults.

Association Analysis of Candidate Gene Polymorphisms and Audiometric Measures of Noise-Induced Hearing Loss in Young Musicians

INTRODUCTION

This study aimed to investigate the association between candidate genetic variants and audiometric measures of noise-induced hearing loss (NIHL) in young musicians.

METHODS

The study analyzed a database by Phillips et al. (Feasibility of a bilateral 4000-6000 Hz notch as a phenotype for genetic association analysis. Int J Audiol 2015;54:645-52.) which included behavioral hearing thresholds, distortion-product otoacoustic emissions (DPOAE), tympanometric, and genetic data of 166 participants meeting the inclusion criteria. Nineteen single nucleotide polymorphisms (SNPs) in 13 cochlear genes previously associated with NIHL in factory workers were included in the present investigation. The average hearing threshold at 3000 and 4000 Hz (AHT) and average DPOAE signal to noise ratio (DPOAE SNR) in both ears were calculated.

RESULTS

The regression analyses showed that two SNPs- one in KCNE1 (rs2070358) and the other in CAT (rs12273124) revealed a statistically significant relationship with DPOAE SNR in both ears. Two SNPs in MYH14 and one in GJB4 revealed a significant association with DPOAE SNR in the left ear. Two SNPs in HSP70, one in CDH23 and one in KCNJ10 showed significant association with DPOAE SNR in the right ear. None of the included SNPs showed association with AHT in both ears.

CONCLUSIONS

A genetic variant in KCNE1 was associated with the strength of the cochlear amplifier as assessed by DPOAE SNR. Musicians carrying causal genetic variants to NIHL might exhibit changes in their auditory functions early in the lifespan even when most subjects had their hearing thresholds within normal limits. These participants are likely to show the clinical manifestation of NIHL in the future if no preventive measures are applied.

The Effects of Short-Term and Long-term Hearing Changes on Music Exposure: A Systematic Review and Meta-Analysis

The present study explores the scientific evidence on whether music exposure temporarily or permanently affects hearing sensitivity in young adults. Six electronic databases were searched using related keywords for the four categories of personal listening devices, listening habits, hearing outcomes, and age. The Hedges’ g and its 95% confidence intervals (CIs) were estimated. A Higgins I² was also used to check for heterogeneity. To test for publication bias, funnel plots were drawn using Egger’s regression. Based on the inclusion criteria, 16 studies were divided into two groups to identify short-term hearing changes (n = 7) and long-term hearing changes (n = 9). In the short term, there was no significant immediate change in the thresholds or amplitudes after the music exposure, although pure-tone thresholds (PTAs) and distortion product otoacoustic emissions (DPOAEs) did show the highest effect size (−0.344, CI −0.727 to 0.038) and (0.124, CI −0.047 to 0.296) at 4 kHz. On the other hand, for long-term hearing changes, the PTA provided the highest effect size at 6 kHz (−0.525, CI −0.897 to −0.154) and 8 kHz (–0.486, CI −0.819 to −0.152), while also implying that habitual and repeated personal listening device (PLD) usage can act on some significant hearing changes in audiological tests. We conclude that the use of a PLD produces a few temporary hearing changes at 4 kHz after its use but that the changes are then reversed. However, it is important to note heavy PLD users’ experience regarding permanent changes in their hearing thresholds at high frequencies, and the public should be educated on this issue.

Assessment of Safe Listening Intentional Behavior Toward Personal Listening Devices in Young Adults

Recreational noise-induced hearing loss (RNIHL) is a highly preventable disorder that is commonly seen in teenagers and young adults. Despite the documented negative effects of RNIHL, it is still challenging to persuade people to adopt safe listening behaviors. More research is needed to understand the underlying factors guiding listeners’ intentions to engage in safe listening habits. We used the Theory of Planned Behavior (TPB) to identify attitudes, social norms, and behavioral control in 92 young adults toward two intentional behaviors related to safe listening habits while listening to their personal listening devices: (1) lowering the intensity of loud music, and (2) shortening the listening duration of loud music. Using a Qualtrics survey, the major factors of the TPB model as they relate to the participants’ intention to engage in risk-controlling behavior were assessed. Behavioral intentions to turn the music down and listen for shorter durations were thought to be predicted by the TPB factors (attitudes, social norms, and perceived behavioral control). Linear regression findings indicated that the overall TPB models were significant. Positive attitudes toward turning the music down and shortening the durations were significantly associated with intentions to engage in non-risky behavior, more so for the former behavior.

The correlation between hair and eye colour and contralateral suppression of otoacoustic emissions

Genetics and environmental factors frequently influence individual's susceptibility to hearing loss. It is postulated that melanin in the inner ear is related to individual's susceptibility to noise induced hearing loss (NIHL). General pigmentation in turn, suspected to be related to the amount of pigmentation in the inner ear. The amount of melanin in the inner ear is said to modulate the endocochlear potential and provide an otoprotective effect.

AIM

The study aimed to determine the relationship between the contralateral suppression of otoacoustic emissions (CSOAE) in individuals with brown eyes and hair, and blue eyes and blond hair, and temporary emission shift (TES) after short-term noise exposure.

SETTING AND DESIGN

The research was conducted using a quantitative research design with a quasi-experimental repeated within the subject design to compare the CSOAE in subjects with different hair and eyes colour with TES after short-term noise exposure. Quantitative research was used to determine the relationship between the measurable variables to predict occurrence.

MATERIAL AND METHOD

The hearing sensitivity of young adults was determined by using pure tone audiometry followed by CSOAE's and distortion product otoacoustic emissions (DPOAE) before listening to music for one hour individually. Pure tone audiometry and DPOAE's were repeated after music exposure to determine the amount of TES and temporary threshold shift (TTS).

STATISTICAL ANALYSIS USED

One-way ANOVA was used during the analysis of the data obtained during this research study, in addition to, two-tailed Wilcoxon Sign Rank test and Friedman's test. In all analyses, a 95% level of significance (P<0.05) was used.

RESULTS

No statistically significant difference between efferent suppression was measured by CSOAE's between the participant groups. A larger TTS at 4000 Hz and TES at 2000 Hz was evident in the blue eyes and blond hair group after short-term music exposure. Conclusion: CSOAE's were unable to predict which group of individuals were more susceptible to NIHL after short-term noise exposure.

A preliminary study on time-compressed speech recognition in noise among teenage students who use personal listening devices

OBJECTIVE

To compare speech perception obtained with different time compression rates in teenagers that do or do not use personal listening devices (PLDs).

DESIGN

Teenagers in a high school were recruited to complete questionnaires reporting their recreational noise exposure using PLDs. The dose of individual recreational noise exposure was calculated. The individuals with the most and least doses of recreational noise were selected and grouped into PLD users and non-PLD users. Normal rate and time-compressed (60% and 70%) speech recognition in quiet and noisy conditions was measured.

STUDY SAMPLE

PLD user and non-PLD user group each included 20 participants.

RESULTS

ANOVA analysis showed that the effect of group, background, compression rate, and interactions between any two factors are significant. Post hoc analysis showed that the speech recognition scores with normal rate in quiet and noise and those obtained from time-compressed speech in the quiet condition were not significantly different between PLD users and non-PLD users. However, differences in the time-compressed speech recognition scores (60% and 70%) in noisy conditions between the two groups were statistically significant.

CONCLUSIONS

The fast-speed speech recognition in noise decreased significantly in PLD users compared with that in non-PLD users selected by extreme entertainment exposure.

Listening to music with personal listening devices: monitoring the noise dose using a smartphone application

OBJECTIVES

To monitor listening habits to personal listening devices (PLDs) using a smartphone application and to compare actual listening habits to self-report data.

DESIGN

Two stages: self-report listening habits questionnaire, and real-time monitoring of listening habits through a smartphone application.

STUDY SAMPLE

Overall 117 participants aged 18-34 years (mean 25.5 years) completed the questionnaire, and of them, 40 participants (mean age: 25.2 years) were monitored for listening habits during two weeks.

RESULTS

Questionnaire main findings indicated that most of the participants reported listening for 4-7 days a week, for at least 30 min at high listening levels with volume control settings at 75-100%. Monitored data showed that actual listening days per week were 1.5-6.5 d, with mean continuous time of 1.56 h, and mean volume control setting of 7.39 (on a scale of 1-15). Eight participants (22%) were found to exceed the 100% noise dose at least once during the monitoring period. One participant (2.7%) exceeded the weekly 100% daily noise dose. Correlations between actual measurements and self-report data were low to moderate.

CONCLUSIONS

Results confirmed the feasibility of monitoring listening habits by a smartphone application, and underscore the need for such a tool to enable safe listening behaviour.

Musicianship enhances ipsilateral and contralateral efferent gain control to the cochlea

Human hearing sensitivity is easily compromised with overexposure to excessively loud sounds, leading to permanent hearing damage. Consequently, finding activities and/or experiential factors that distinguish "tender" from "tough" ears (i.e., acoustic vulnerability) would be important for identifying people at higher risk for hearing damage. To regulate sound transmission and protect the inner ear against acoustic trauma, the auditory system modulates gain control to the cochlea via biological feedback of the medial olivocochlear (MOC) efferents, a neuronal pathway linking the lower brainstem and cochlear outer hair cells. We hypothesized that a salient form of auditory experience shown to have pervasive neuroplastic benefits, namely musical training, might act to fortify hearing through tonic engagement of these reflexive pathways. By measuring MOC efferent feedback via otoacoustic emissions (cochlear emitted sounds), we show that dynamic ipsilateral and contralateral cochlear gain control is enhanced in musically-trained individuals. Across all participants, MOC strength was correlated with the years of listeners' training suggested that efferent gain control is experience dependent. Our data provide new evidence that intensive listening experience(s) (e.g., musicianship) can strengthen the ipsi/contralateral MOC efferent system and sound regulation to the inner ear. Implications for reducing acoustic vulnerability to damaging sounds are discussed.

TE and DP otoacoustic emission data from an Australian cross-sectional hearing study

OBJECTIVE

This paper presents a summary of otoacoustic emission (OAE) data collected as part of an Australian hearing health survey ( Carter, 2011 ; Williams et al, 2014 ) designed to: (1) examine the relationship between audiological indicators and participant characteristics, and (2) extract audiological data suitable for reference use.

DESIGN

Cross-sectional cohort study. Distortion product (DP) OAE and transient evoked (TE) OAE measures.

STUDY SAMPLE

Age range 11-35 years; N = 1386 participants (2672 test ears).

RESULTS

Descriptive statistics for amplitude and signal-to-noise ratio (SNR) were calculated for 327 participants (589 test ears; age 13 to 32 years). DPOAE amplitudes down to the 25th percentile were > 0 dB SPL for test frequencies up to 6 kHz. TEOAE SNRs down to the 25th percentile were > 6 dB SPL up to 4 kHz.

SUMMARY

This dataset can be used as a clinical reference for similar populations, providing that the same test parameters are used.

CONCLUSIONS

The clinical significance of OAE testing would be greater if agreed criteria were available. These data could be pooled with other datasets to build a substantial OAE database, similar to the existing international standards for pure-tone hearing threshold levels (HTLs) ( ISO, 2000 ).

Subjective and clinically assessed hearing loss; a cross-sectional register-based study on a swedish population aged 18 through 50 years

OBJECTIVES

Questionnaire studies suggest that hearing is declining among young adults. However, few studies have examined the reliability of hearing questionnaires among young adult subjects. This study examined the associations between pure tone audiometrically assessed (PTA) hearing loss and questionnaire responses in young to middle aged adults.

MATERIALS AND METHODS

A cross-sectional study using questionnaire and screening PTA (500 through 6000 Hz) data from 15322 Swedish subjects (62% women) aged 18 through 50 years. PTA hearing loss was defined as a hearing threshold above 20 dB in both ears at one or more frequencies. Data were analysed with chi-square tests, nonlinear regression, binary logistic regression, and the generalized estimating equation (GEE) approach.

RESULTS

The prevalence of PTA hearing loss was 6.0% in men and 2.9% in women (p < 0.001). Slight hearing impairment was reported by 18.5% of the men and 14.8% of the women (p < 0.001), whereas 0.5% of men and women reported very impaired hearing. Using multivariate GEE modelling, the odds ratio of PTA hearing loss was 30.4 (95% CI, 12.7-72.9) in men and 36.5 (17.2-77.3) in women reporting very impaired hearing. The corresponding figures in those reporting slightly impaired hearing were 7.06 (5.25-9.49) in men and 8.99 (6.38-12.7) in women. These values depended on the sound stimulus frequency (p = 0.001). The area under the ROC curve was 0.904 (0.892-0.915) in men and 0.886 (0.872-0.900) in women.

CONCLUSIONS

Subjective hearing impairment predicted clinically assessed hearing loss, suggesting that there is cause for concern as regards the future development of hearing in young to middle-aged people.

Otoacoustic emissions before and after listening to music on a personal player

Background

The problem of the potential impact of personal music players on the auditory system remains an open question. The purpose of the present study was to investigate, by means of otoacoustic emissions (OAEs), whether listening to music on a personal player affected auditory function.

Material/Methods

A group of 20 normally hearing adults was exposed to music played on a personal player. Transient evoked OAEs (TEOAEs) and distortion product OAEs (DPOAEs), as well as pure tone audiometry (PTA) thresholds, were tested at 3 stages: before, immediately after, and the next day following 30 min of exposure to music at 86.6 dBA.

Results

We found no statistically significant changes in OAE parameters or PTA thresholds due to listening to the music.

Conclusions

These results suggest that exposure to music at levels similar to those used in our study does not disturb cochlear function in a way that can be detected by means of PTA, TEOAE, or DPOAE tests.

Sound pressure level generated by individual portable sound equipment

Introdução

O uso de equipamentos portáteis sonoros individuais pode ser um risco auditivo, pois o som é gerado diretamente no meato acústico externo. Acredita-se que fones diferentes proporcionam amplificações diferentes, pois causam variações de volume e de ressonância conforme suas inserções.

Objetivos

Verificar a pressão sonora a que jovens estão expostos quando fazem uso de equipamentos sonoros portáteis individuais com dois diferentes fones: de inserção e de inserção anatômico.

Material e método

Trata-se de uma pesquisa experimental. Para tanto, foram feitas medições em 54 orelhas de 27 jovens com idades entre 18 e 30 anos, com os dois tipos de fones. Também foram registrados picos de ressonância da orelha externa com e sem fone.

Resultados

Observou-se que o fone de inserção anatômico apresenta aumento do nível de pressão sonora estatisticamente significante em comparação com o fone de inserção para todas as frequências avaliadas. Não há uma correlação entre o novo pico de ressonância do meato fechado e a frequência na qual se obteve os maiores níveis de pressão sonora com o fone. Observou-se diferença estatisticamente significativa entre orelhas para algumas frequências com os diferentes fones.

Conclusão

o fone de inserção anatômico gera um maior nível de pressão sonora que o fone de inserção.

© 2014 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Publicado por Elsevier Editora Ltda. Todos os direitos reservados.

Digital music exposure reliably induces temporary threshold shift in normal-hearing human subjects

OBJECTIVES

One of the challenges for evaluating new otoprotective agents for potential benefit in human populations is the availability of an established clinical paradigm with real-world relevance. These studies were explicitly designed to develop a real-world digital music exposure that reliably induces temporary threshold shift (TTS) in normal-hearing human subjects.

DESIGN

Thirty-three subjects participated in studies that measured effects of digital music player use on hearing. Subjects selected either rock or pop music, which was then presented at 93 to 95 (n = 10), 98 to 100 (n = 11), or 100 to 102 (n = 12) dBA in-ear exposure level for a period of 4 hr. Audiograms and distortion product otoacoustic emissions (DPOAEs) were measured before and after music exposure. Postmusic tests were initiated 15 min, 1 hr 15 min, 2 hr 15 min, and 3 hr 15 min after the exposure ended. Additional tests were conducted the following day and 1 week later.

RESULTS

Changes in thresholds after the lowest-level exposure were difficult to distinguish from test-retest variability; however, TTS was reliably detected after higher levels of sound exposure. Changes in audiometric thresholds had a "notch" configuration, with the largest changes observed at 4 kHz (mean = 6.3 ± 3.9 dB; range = 0-14 dB). Recovery was largely complete within the first 4 hr postexposure, and all subjects showed complete recovery of both thresholds and DPOAE measures when tested 1 week postexposure.

CONCLUSIONS

These data provide insight into the variability of TTS induced by music-player use in a healthy, normal-hearing, young adult population, with music playlist, level, and duration carefully controlled. These data confirm the likelihood of temporary changes in auditory function after digital music-player use. Such data are essential for the development of a human clinical trial protocol that provides a highly powered design for evaluating novel therapeutics in human clinical trials. Care must be taken to fully inform potential subjects in future TTS studies, including protective agent evaluations, that some noise exposures have resulted in neural degeneration in animal models, even when both audiometric thresholds and DPOAE levels returned to pre-exposure values.

Facing the music: pre- and postconcert assessment of hearing in teenagers

OBJECTIVE

Determine the effect of exposure to a single rock/pop concert on pure-tone hearing thresholds and outer hair cell function in teenagers.

STUDY DESIGN

Repeated measures pre- and postconcert assessment of hearing.

SETTING

Mobile hearing conservation test vehicle and large indoor concert venue.

SUBJECTS

Twenty-nine normal-hearing teenagers and young adults ages 13 to 20 years.

INTERVENTION

Attendance at a public rock/pop concert.

MAIN OUTCOME MEASURES

Pre- and postconcert pure-tone thresholds in both ears from 500 Hz to 8 kHz, pure-tone average (PTA) for 2, 3, and 4 kHz, distortion product otoacoustic emissions (DPOAEs), proportion of subjects experiencing a PTA change of 10 dB or greater.

RESULTS

Concert sound levels at the subjects' position averaged 98.5 dBA. Only 3 subjects used the hearing protection provided. Thresholds for 2 to 6 kHz increased significantly from pre- to postconcert (p ≤ 0.001). The increase in PTA (2, 3, and 4 kHz) between test intervals averaged 6.3 and 6.5 dB for the right and left ears, respectively, and 33.3% of subjects had a threshold shift of 10 dB or greater in the PTA in at least 1 ear (p ≤ 0.001). The number of subjects experiencing a reduction in DPOAE amplitude (17/25) and the change in mean amplitude were statistically significant (p ≤ 0.001 and p ≤ 0.004, respectively).

CONCLUSION

Exposure to a single live-music rock/pop concert can produce a threshold shift and decrease in otoacoustic emissions amplitude indicating impact on outer hair cell function. Results clearly indicate a need for research on this public health issue regarding "safe" listening levels, especially in younger people with more years for accrual of damage.

Increased vitamin plasma levels in Swedish military personnel treated with nutrients prior to automatic weapon training

Noise-induced hearing loss (NIHL) is a significant clinical, social, and economic issue. The development of novel therapeutic agents to reduce NIHL will potentially benefit multiple very large noise-exposed populations. Oxidative stress has been identified as a significant contributor to noise-induced sensory cell death and NIHL, and several antioxidant strategies have now been suggested for potential translation to human subjects. One such strategy is a combination of beta-carotene, vitamins C and E, and magnesium, which has shown promise for protection against NIHL in rodent models, and is being evaluated in a series of international human clinical trials using temporary (military gunfire, audio player use) and permanent (stamping factory, military airbase) threshold shift models (NCT00808470). The noise exposures used in the recently completed Swedish military gunfire study described in this report did not, on average, result in measurable changes in auditory function using conventional pure-tone thresholds and distortion product otoacoustic emission (DPOAE) amplitudes as metrics. However, analysis of the plasma samples confirmed significant elevations in the bloodstream 2 hours after oral consumption of active clinical supplies, indicating the dose is realistic. The plasma outcomes are encouraging, but clinical acceptance of any novel therapeutic critically depends on demonstration that the agent reduces noise-induced threshold shift in randomized, placebo-controlled, prospective human clinical trials. Although this noise insult did not induce hearing loss, the trial design and study protocol can be applied to other populations exposed to different noise insults.

Preferred listening levels of personal listening devices in young teenagers: self reports and physical measurements

OBJECTIVE

To assess the potential risk of hearing loss to young listeners, due to the use of personal listening devices (PLDs).

DESIGN

The study included two parts: (1) A self-report questionnaire on music listening habits, and (2) Physical measurements of preferred listening levels, in quiet and in everyday background noise.

STUDY SAMPLE

Young teenagers aged 13 to 17 years. Part 1 included 289 participants with mean age of 14 years. Part 2 included 11 and 74 participants (2A and 2B) with a mean age of 15 years. Eleven listened to PLDs in quiet conditions (2A) and 74 in everyday background noise (2B).

RESULTS

Questionnaire main findings indicated that most of the participants reported high or very high volume settings and demonstrated low awareness towards loud music listening consequences. Physical measurements corrected for diffuse field indicated mean preferred listening levels of: 82 (SD = 9) dBA in quiet, and 89 (SD = 9) dBA in the presence of background noise. The potential risk to hearing of PLDs users was calculated using the 8 hour equivalent level.

CONCLUSION

More than 25% of the participants in the noisy condition were found to be at risk according to occupational damage risk criteria NIOSH, 1998.

Monitoring carboplatin ototoxicity with distortion-product otoacoustic emissions in children with retinoblastoma

OBJECTIVE

Carboplatin is a common chemotherapy agent with potential ototoxic side effects that is used to treat a variety of pediatric cancers, including retinoblastoma. Retinoblastoma is a malignant tumor of the retina that is usually diagnosed in young children. Distortion-product otoacoustic emission tests offer an effective method of monitoring for ototoxicity in young children. This study was designed to compare measurements of distortion-product otoacoustic emissions obtained before and after several courses of carboplatin chemotherapy in order to examine if (a) mean distortion-product otoacoustic emission levels were significantly different; and (b) if criterion reductions in distortion-product otoacoustic emission levels were observed in individual children.

METHODS

A prospective repeated measures study. Ten children with a median age of 7.6 months (range, 3-72 months) diagnosed with unilateral or bilateral retinoblastoma were examined. Distortion-product otoacoustic emissions were acquired from both ears of the children with 65/55 dB SPL primary tones (f(2)=793-7996 Hz) and a frequency resolution of 3 points/octave. Distortion-product otoacoustic emission levels in dB SPL were measured before chemotherapy treatment (baseline measurement) and after 3-4 courses of chemotherapy (interim measurement). Comparisons were made between baseline and interim distortion-product otoacoustic emission levels (collapsed across ears). Evidence of ototoxicity was based on criterion reductions (≥ 6 dB) in distortion-product otoacoustic emission levels.

RESULTS

Significant differences between baseline and interim mean distortion-product otoacoustic emission levels were only observed at f(2) = 7996 Hz. Four children exhibited criterion reductions in distortion-product otoacoustic emission levels.

CONCLUSIONS

Mean distortion-product otoacoustic emission levels at most frequencies were not changed following 3-4 courses of carboplatin chemotherapy in children with retinoblastoma. However, on an individual basis, children receiving higher doses of carboplatin exhibited criterion reductions in distortion-product otoacoustic emission level at several frequencies. These findings suggest that higher doses of carboplatin affect outer hair cell function, and distortion-product otoacoustic emission tests can provide useful information when monitoring children at risk of developing carboplatin ototoxicity.

Otoacoustic emissions in a hearing conservation program: general applicability in longitudinal monitoring and the relation to changes in pure-tone thresholds

The hearing status of workers (N = 233) in a printing office was assessed twice within seventeen months by pure-tone audiometry and otoacoustic emissions (OAEs). One of the questions was how a quality criterion of OAE-measurements based on a minimum signal-to-noise-ratio (SNR) would affect the applicability on the entire population. Secondly, effects of noise exposure were investigated in overall changes in audiogram and OAE-measurements. For TEOAEs (transient evoked OAEs) in the frequency band of 4 kHz, only 55% of the data points meet the SNR-inclusion criterion. For DPOAEs (distortion product OAEs) around 6 kHz approximately 80% of the data points satisfy the criterion. Thus OAEs have a limited applicability for monitoring the hearing status of this entire population. Audiometry shows significant deteriorations at 6 and 8 kHz. TEOAEs show a significant decline at all frequency bands (1-4 kHz), DPOAEs between 4 and 8 kHz and less pronounced between 1 and 2 kHz. On group level, OAEs show a decline in a larger frequency region than the audiogram, suggesting an increased sensitivity of OAEs compared to audiometry.

Temporary reduction of distortion product otoacoustic emissions (DPOAEs) immediately following auditory brainstem response (ABR)

The hearing status of an experimental animal is typically assessed in the laboratory setting by the combined use of auditory brainstem response (ABR) and distortion product otoacoustic emissions (DPOAEs), carried out in succession, with the former assay preceding the latter. This study reports a cautionary finding that the use of this accepted regimen yields a reduced DPOAE response. When the DPOAEs were performed after ABR testing, transient reduction of the DPOAE amplitudes was observed at all frequencies in both the inbred, C57/B6 and FVB/N, and the outbred, SW mouse strains. DPOAEs were reduced post-ABR in multiple mouse strains which suggests that this finding is not strain-specific but a general consequence of the preceding ABR analysis. The reduction in DPOAE was temporary: when re-tested at one hour, DPOAE amplitudes recovered to pre-ABR levels. In contrast to the ABR's impact on DPOAE response, ABR thresholds were not altered or reduced when preceded immediately by DPOAE measurements. The molecular alterations underlying the ABR-induced transient reduction of DPOAE remain to be determined. To investigate the potential role of reactive oxygen species in post-ABR DPOAE reduction, transgenic mice over-expressing SOD1, the cytoplasmic enzyme critical for removal of superoxide radicals were subjected to the same auditory testing regimen. Similar to their wild type littermates, the SOD1 transgenic mice also demonstrated post-ABR DPOAE reduction, and thus do not support a role for superoxide radicals in transient reduction of DPOAE. While toxic noise exposure is known to negatively impact OAE, transient decrease in DPOAE levels following standard ABR assay has not been previously described. A practical outcome from this study is a recommendation for reversal of the traditional order for carrying out auditory tests, with the OAE measurements preceding ABR assessment, thus ensuring that the DPOAE response is unaffected.

Analysis of distortion product otoacoustic emission spectra in normal-hearing adults

PURPOSE

To evaluate the ability of distortion product otoacoustic emission (DPOAE) spectral characteristics to distinguish between ears with variable hearing sensitivity within the normal range.

METHOD

Distortion product grams (DP-grams) were acquired with primary tones decremented in 1/8-octave steps and primary-tone levels presented at 65 dB SPL (L1) and 45 dB SPL (L2) across an f2 frequency range of 842-7996 Hz from 22 normal-hearing adults (44 ears). Hearing thresholds of ears classified in Group A (n = 22) were better than ears classified in Group B (n = 22). Examined parameters of the DP-grams included spectral peak occurrence, peak height, peak width, and DPOAE levels. Analyses of variance were conducted to determine whether DP-gram parameters differed between Group A and Group B.

RESULTS

For the low-resolution DP-grams examined in this study, no significant between-group differences in peak occurrence, peak height, and peak width were observed. DPOAE levels were significantly higher in ears classified in Group A compared with ears classified in Group B in individuals with symmetrical hearing.

CONCLUSIONS

Although spectral peaks are evident in DP-grams acquired with low resolution of the primary tones, DPOAE levels are more effective in distinguishing ears with greater hearing sensitivity from less sensitive ears.