Noise induced hearing loss in dance music disc jockeys and an examination of sound levels in nightclubs

Evaluation of Lifetime Noise Exposure History Reporting

PURPOSE

The purpose of this study is to critically evaluate lifetime noise exposure history (LNEH) reporting. First, two different approaches to evaluate the cumulative LNEH were compared. Second, individual LNEH was associated with the subjects' hearing status. Third, loudness estimates of exposure activities, by means of Jokitulppo- and Ferguson-based exposure levels, were compared with dosimeter sound-level measurements.

METHOD

One hundred one young adults completed the questionnaires, and a subgroup of 30 subjects underwent audiological assessment. Pure-tone audiometry, speech-in-noise intelligibility, distortion product otoacoustic emissions, auditory brainstem responses, and envelope following responses were included. Fifteen out of the 30 subjects took part in a noisy activity while wearing a dosimeter.

RESULTS

First, results demonstrate that the structured questionnaire yielded a greater amount of information pertaining to the diverse activities, surpassing the insights obtained from an open-ended questionnaire. Second, no significant correlations between audiological assessment and LNEH were found. Lastly, the results indicate that Ferguson-based exposure levels offer a more precise estimation of the actual exposure levels, in contrast to Jokitulppo-based estimates.

CONCLUSIONS

We propose several recommendations for determining the LNEH. First, it is vital to define accurate loudness categories and corresponding allocated levels, with a preference for the loudness levels proposed by Ferguson et al. (2019), as identified in this study. Second, a structured questionnaire regarding LNEH is recommended, discouraging open-ended questioning. Third, it is essential to include a separate category exclusively addressing work-related activities, encompassing various activities for more accurate surveying.

Identifying Targets for Interventions to Increase Earplug Use in Noisy Recreational Settings: A Qualitative Interview Study

Earplugs can reduce the risk of hearing loss and tinnitus. However, earplug use during noisy recreational activities is uncommon, and methods for increasing uptake and regular use have had limited efficacy. The aim of the present study was to examine barriers and enablers of ever-performers (e.g., people who have used earplugs) and never-performers (e.g., people who have not used earplugs) to identify targets to inform the content of interventions to increase uptake and regular use of earplugs in recreational settings. The Capabilities, Opportunities, and Motivations model of Behaviour (COM-B) informed the outline for 20 semi-structured telephone interviews (ever-performers, N = 8, age range = 20-45 years; never-performers, N = 12; age range = 20-50 years). Thematic analysis was used to identify barriers and enablers to earplug use, which were mapped onto the Theoretical Domains Framework (TDF). Six key domains of the TDF were identified. Ever-performers described being more exposed to 'social influences' (e.g., facilitators such as friends/peers) and were more positive than never-performers concerning 'beliefs about consequences' (e.g., earplug protection outweighs any negative effects on listening/communication). Involvement of 'emotion' (e.g., fear of losing ability to listen to music) and 'reinforcement' tactics (e.g., creating habits/routines) were discussed by ever-performers, but were not mentioned by never-performers. Both groups reported lack of 'environmental context and resources' (e.g., prompts and cues), and their own 'memory, attention, and decision processes' (e.g., deciding when to use earplugs) as barriers to earplug use. The present research identifies the variables that would need to change in order to increase earplug uptake and use in recreational settings among ever-performers and never-performers. Further work is required to translate these findings into testable interventions by selecting appropriate intervention functions (e.g., modelling), policy categories (e.g., communication/marketing), behaviour change techniques (e.g., demonstration of behaviour), and mode of delivery (e.g., face-to-face).

Loud Music and Leisure Noise Is a Common Cause of Chronic Hearing Loss, Tinnitus and Hyperacusis

High sound levels capable of permanently damaging the ear are experienced not only in factories and war zones but in concert halls, nightclubs, sports stadiums, and many other leisure environments. This review summarizes evidence that loud music and other forms of "leisure noise" are common causes of noise-induced hearing loss, tinnitus, and hyperacusis, even if audiometric thresholds initially remain within clinically normal limits. Given the huge global burden of preventable noise-induced hearing loss, noise limits should be adopted in a much broader range of settings, and education to promote hearing conservation should be a higher public health priority.

Hearing health information in Malaysian public schools: a step towards addressing a public health concern

OBJECTIVE

This study aimed to examine hearing-related information in public school textbooks in Malaysia to gain insight into the country's hearing health education.

DESIGN

Qualitative content analysis on all textbooks used in Malaysian public schools in the year 2019 were conducted to identify the content and structure of information delivery through 11 years of formal education. Information related to hearing health was extracted and categorised according to the themes that emerged. Further analysis was done to characterise the usefulness of the information in promoting active hearing care based on the type of information delivered.

STUDY SAMPLE

A total of 148 elementary and secondary school textbooks were reviewed.

RESULTS

Fourteen textbooks (4 elementary and 10 secondary levels) were found to have relevant hearing health information covering topics of sound, ear and hearing, noise and hearing loss. The contents were mostly theoretical and lacked information about noise-induced hearing loss and proper hearing care.

CONCLUSION

Minimal hearing health information was present in the Malaysian school curriculum. The content was inadequate for teaching students about hearing loss prevention. Areas of improvement and research are recommended to improve school-based hearing health education in Malaysia.

Which interventions increase hearing protection behaviors during noisy recreational activities? A systematic review

Background

Hearing loss and tinnitus are global concerns that can be reduced through hearing protection behaviors (e.g., earplug use). Little is known about the effectiveness of interventions to increase hearing protection use in recreational domains. For the first time we review systematically the effectiveness of such interventions.

Methods

Systematic searches of nine databases, as well as grey literature and hand-searching, were conducted. Any study design was included if it assessed quantitatively a purposeful attempt to increase hearing protection in recreational settings. Studies were excluded if they assessed noise exposure from occupational sources and headphones/earphones, as these have been reviewed elsewhere. PROSPERO protocol: CRD42018098573.

Results

Eight studies were retrieved following the screening of 1908 articles. Two pretest-posttest studies detected a small to medium effect (d ≥ 0·3 ≤ 0·5), one a small effect (d ~ =0·2) and two no real effect. Three posttest experimental studies detected small to medium effects (d ≥ 0·3 ≤ 0·5). Studies were rated as “poor quality” and 17 out of a possible 93 behavior change techniques were coded, with the majority targeting the intervention function ‘education’.

Conclusions

Hearing loss and tinnitus due to recreational noise exposure are major public health concerns yet very few studies have examined preventive interventions. The present systematic review sets the agenda for the future development and testing of evidence-based interventions designed to prevent future hearing loss and tinnitus caused by noise in recreational settings, by recommending systematic approaches to intervention design, and implementation of intervention functions beyond education, such as incentivization, enablement and modeling.

Noise levels at baseball stadiums and the spectators' attitude to noise

Background:

Many public health professionals have expressed concern that regular participation in recreational settings with high noise levels might induce hearing loss. This study measures the noise levels in a baseball stadium and analyzes baseball fans’ attitude of effect of recreational noise exposure on their hearing.

Methods:

In the baseball stadium, noise levels from the beginning to the end of four games were measured in four seating sections, the red, blue, navy, and outfield sections using a sound level meter. For the survey sample, 344 randomly selected participants who visited the stadium and/or were baseball fans completed a 16-question survey on their noise exposure during the game and on the potential risk of hearing loss.

Results:

The LAeq average of the 16 measures produced 91.7 dBA, showing a significantly high noise level in the red and navy sections. As a function of frequency by LZeq analysis, the noise levels of low frequencies between 0.05 and 1 kHz were significantly higher than other frequencies except for the outfield section, but the levels abruptly decreased above 1 kHz. Despite the very high noise levels, 70% of the respondents preferred sitting in either the red or the navy section to be closer to the cheerleaders and to obtain a good view. Most respondents reported that they did not consider wearing earplugs, and one-third experienced hearing muffled speech after the game. Notably, they agreed that an information announcement regarding loud noise and hearing protection was needed at the stadium.

Conclusions:

We conclude that the noise levels in baseball stadiums are high enough to cause hearing damage and/or tinnitus later when applying a rule of 85 dB LAeq for 8 hours with a 3-dB exchange rate. We expect these results to improve public education regarding safe noise exposure during popular sports activities.

Risk of noise-induced hearing loss due to recreational sound: Review and recommendations

This review was conducted to address three questions related to recreational sound exposure: (1) what criteria are used to determine noise exposure limits, (2) are there differences in the risk of hearing loss from occupational noise versus recreational sound, and (3) what is an appropriate exposure limit for recreational sound? For the first question, most standards specify an 8-h occupational noise exposure limit (L_EX) of 85 dBA. This limit assumes that some workers exposed at the limit will develop hearing loss. To eliminate the risk of hearing loss, a 24-h equivalent continuous level (L_EQ24h) limit of 70 dBA is appropriate. For the second question, there is some evidence that the effects of occupational noise on hearing may be worse than energetically equivalent recreational sound. Limits developed for noise are nevertheless applicable to recreational sound, and use of existing statistical models to predict hearing loss from recreational sound is appropriate, with the caveat that these models are limited to durations ≤40 years. For the third question, a recreational sound limit of 80 dBA L_EX, equivalent to a 75 dBA L_EQ24h, will virtually eliminate the risk of recreationally induced hearing loss in adults. Lower limits may be warranted for vulnerable or susceptible individuals.

Risk Factors for Distortion Product Otoacoustic Emissions in Young Adults

Young adults with normal hearing may exhibit risk factors for hearing loss. The purpose of this study was to evaluate how self-reported personal music (PM) system volume use, preferred listening level, and self-reported alcohol use affects distortion product otoacoustic emissions (DPOAEs). Two-hundred, sixteen young adults, 161 women and 55 men, participated. Questionnaire data included the PM system and alcohol use. DPOAEs were obtained from 1–6 kHz and collapsed into 1/3rd octave bands and a probe microphone was used to determine preferred listening level. Alcohol was defined as drinks per month (DPM), categorized as No, Light (≤14), and Heavy (>14). Men who reported loud/very loud volume use had statistically significant lower DPOAEs at 1.5, 2, and 3 kHz than men who reported lower volume use. Light and Heavy DPM men had lower DPOAEs at 1.5, 2, and 3 kHz than no DPM men, but this was not statistically significant. There were no DPOAE differences for either variable in women and there was no association between preferred listening level and DPOAEs for women or men. Men who reported loud/very loud volume use and any DPM had poorer mid-frequency DPOAEs. There was not an association for volume use or DPM and DPOAEs in women.

Pilot study of patron sound level exposure in loud restaurants, bars, and clubs in New York city

Visiting restaurants, bars, clubs, and lounges is a regular part of urban cultural life for residents and tourists alike; however, anecdotal reports and diner surveys suggest that sound levels are excessive and diners dislike them. High sound levels in these venues can contribute to both patron and employee overexposure, and young people may be particularly at risk. To supplement the paucity of literature and data on noise in urban venues, patron noise exposure was measured inside a sample of loud New York City restaurants, bars, clubs, and lounges. Sound level measurements were obtained in 59 venues. Field staff conducted one 20-162 minute visit per venue on a Thursday, Friday, or Saturday evening. The equivalent continuous sound pressure level on the A-scale (L_Aeq) was calculated for each visit. Median and mean L_Aeq among all venues sampled were both 92 decibels (dBA). Clubs and lounges had a higher mean L_Aeq than restaurants and bars (97 vs. 91 dBA, p < 0.05). A greater number of patrons was associated with a higher L_Aeq. Higher L_Aeq values were observed during later hours of the evening (9 PM and later). For 80% (N = 47) of the venues, the L_Aeq was above 85 dBA. In 49% (N = 29) of the venues, the visit exceeded the maximum allowable daily noise dose based on National Institute of Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL) of 85 dBA 8-hr Time-Weighted Average (TWA). Venues should assess indoor sound levels including employee exposure and aim to maintain sound levels that are within NIOSH guidelines.

Hearing in young adults. Part II: The effects of recreational noise exposure

Great concern arises from recreational noise exposure, which might lead to noise-induced hearing loss in young adults. The objective of the current study was to evaluate the effects of recreational noise exposure on hearing function in young adults. A questionnaire concerning recreational noise exposures and an audiological test battery were completed by 163 subjects (aged 18-30 years). Based on the duration of exposure and self-estimated loudness of various leisure-time activities, the weekly and lifetime equivalent noise exposure were calculated. Subjects were categorized in groups with low, intermediate, and high recreational noise exposure based on these values. Hearing was evaluated using audiometry, transient-evoked otoacoustic emissions (TEOAEs), and distortion-product otoacoustic emissions (DPOAEs). Mean differences in hearing between groups with low, intermediate, and high recreational noise exposure were evaluated using one-way analysis of variance (ANOVA). There were no significant differences in hearing thresholds, TEOAE amplitudes, and DPOAE amplitudes between groups with low, intermediate, or high recreational noise exposure. Nevertheless, one-third of our subjects exceeded the weekly equivalent noise exposure for all activities of 75 dBA. Further, the highest equivalent sound pressure levels (SPLs) were calculated for the activities visiting nightclubs or pubs, attending concerts or festivals, and playing in a band or orchestra. Moreover, temporary tinnitus after recreational noise exposure was found in 86% of our subjects. There were no significant differences in hearing between groups with low, intermediate, and high recreational noise exposure. Nevertheless, a long-term assessment of young adults’ hearing in relation to recreational noise exposure is needed.

Hearing in young adults. Part I: The effects of attitudes and beliefs toward noise, hearing loss, and hearing protector devices

There is great concern regarding the development of noise-induced hearing loss (NIHL) in youth caused by high sound levels during various leisure activities. Health-orientated behavior of young adults might be linked to the beliefs and attitudes toward noise, hearing loss, and hearing protector devices (HPDs). The objective of the current study was to evaluate the effects of attitudes and beliefs toward noise, hearing loss, and HPDs on young adults’ hearing status. A questionnaire and an audiological test battery were completed by 163 subjects (aged 18-30 years). The questionnaire contained the Youth Attitude to Noise Scale (YANS) and Beliefs about Hearing Protection and Hearing Loss (BAHPHL). A more positive attitude or belief represented an attitude where noise or hearing loss is seen as unproblematic and attitudes and beliefs regarding HPDs is worse. Hearing was evaluated using (high frequency) pure tone audiometry (PTA), transient evoked and distortion product otoacoustic emissions. First, mean differences in hearing between the groups with different attitudes and beliefs were evaluated using one-way analysis of variance (ANOVA). Second, a χ² test was used to examine the usage of HPDs by the different groups with different attitudes and beliefs. Young adults with a positive attitude had significantly more deteriorated hearing and used HPDs less than the other subjects. Hearing conservation programs (HCPs) for young adults should provide information and knowledge regarding noise, hearing loss, and HPDs. Barriers wearing HPDs should especially be discussed. Further, those campaigns should focus on self-experienced hearing related symptoms that might serve as triggers for attitudinal and behavioral changes.

Amplitude-modulation detection by recreational-noise-exposed humans with near-normal hearing thresholds and its medium-term progression

Noise exposure can affect the functioning of cochlear inner and outer hair cells (IHC/OHC), leading to multiple perceptual changes. This work explored possible changes in detection of amplitude modulation (AM) at three Sensation Levels (SL) for carrier frequencies of 3, 4 and 6 kHz. There were two groups of participants, aged 19 to 24 (Young) and 26 to 35 (Older) years. All had near-normal audiometric thresholds. Participants self-assessed exposure to high-level noise in recreational settings. Each group was sub-grouped into low-noise (LN) or high-noise (HN) exposure. AM detection thresholds were worse for the HN than for the LN sub-group at the lowest SL, for the males only of the Young group and for both genders for the Older group, despite no significant difference in absolute threshold at 3 and 4 kHz between sub-groups. AM detection at the lowest SL, at both 3 and 4 kHz, generally improved with increasing age and increasing absolute threshold, consistent with a recruitment-like process. However, poorer AM detection was correlated with increasing exposure at 3 kHz in the Older group. It is suggested that high-level noise exposure produces both IHC- and OHC-related damage, the balance between the two varying across frequency. However, the use of AM detection offers poor sensitivity as a measure of the effects.

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Young males exhibit deficits in AM detection due to recreational noise exposure.

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Older participants of both genders exhibit a similar deficit due to noise exposure.

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Higher absolute thresholds were associated with better AM detection.

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Results are consistent with a combination of IHC and OHC dysfunction.

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AM detection at 3 kHz was correlated with cumulative noise exposure.

Research Directions for Examining Hazardous Noise at the Theater

Hazardous noise in workplaces is a leading cause of preventable hearing loss among American workers. Traditionally, studies of hazardous noise have been conducted in industrial and manufacturing settings. However, there exists a void in research concerning the prevalence of hazardous noise and the means by which HF/E experts can work to mitigate hazardous noise in less commonly researched settings, such as movie theaters. In this paper, I illustrate and discuss why hazardous noise should be investigated in this setting and highlight relevant research questions associated with investigating noise in theater environments.

British university students' attitudes towards noise-induced hearing loss caused by nightclub attendance

Background:

Over the past 30 years, the prevalence of noise-induced hearing loss among adolescents and young adults has increased. This study aimed to address the current dearth of literature implicating excessive nightclub sound levels (more than 85 dB) as a direct cause of auditory symptoms related to noise-induced hearing loss.

Method:

A questionnaire was completed by 325 students to gauge the frequency of auditory symptoms after nightclub attendance, and to explore knowledge and opinions about noise levels in nightclubs.

Results:

The findings showed that 88.3 per cent of students experienced tinnitus after leaving a nightclub and 66.2 per cent suffered impaired hearing the following morning. In terms of behaviour, 73.2 per cent of students said that the risk of hearing damage would not affect their nightclub attendance, but most students (70.2 per cent) felt that noise levels in nightclubs should be limited to safe volumes.

Conclusion:

A high proportion of students reported experiencing symptoms related to noise-induced hearing loss after attending a nightclub. These findings are relevant to policy makers.

Medical ozone therapy for the inner ear acoustic trauma

OBJECTIVES

The goal of the study was to look at the potential protective effect of ozone therapy by studying its antioxidant and vasodilatation effects against hearing loss caused by acoustic trauma.

METHODS

Thirty-two male Wistar Albino rats were divided into four groups of eight. The 1st group was exposed to acoustic trauma, the 2nd group was treated with ozone initially, and was exposed to acoustic trauma 24 h later, the 3rd group received ozone without trauma, while the 4th group was the control group. The 1st and 2nd groups were exposed to acoustic trauma with 105 dB SPL white band noise for 4h. DPOAE and ABR tests were conducted in all groups on the 1st, 5th, and 10th days after trauma.

RESULTS

In the 1st group, the effects of acoustic trauma continued on days 1, 5 and 10. The 2nd group's DPOAE and ABR results on days 5 and 10 showed significant improvement at all frequencies compared to deterioration on day 1, and the readings were comparable to baseline measurements.

CONCLUSION

Acoustic trauma is a pathology that is experienced frequently and leads to many problems in terms of health and cost. Ozone was demonstrated to be a reparative substance against acoustic trauma and, in addition, it can be supplied and applied easily.

A behavioral measure of the cochlear changes underlying temporary threshold shifts

It is well documented that exposure to recreational noise may result in a temporary threshold shift (TTS) due to cochlear dysfunction. A forward-masking paradigm was used to estimate the relative contribution of inner hair cell (IHC) and outer hair cell (OHC) dysfunction to TTS. Eighteen normal-hearing adults completed a test battery before, immediately after, and one week after attending a loud music venue. Personal dosimeters recorded mean equivalent exposure levels of 99.0 dB A. Shortly after exposure, there was an average TTS of 10.8 dB at 4 kHz, and an average reduction in the estimated gain provided by the OHCs of 11.5 dB. Gain reduction correlated significantly with TTS. The results suggest that OHC dysfunction can account almost entirely for the raised thresholds. For the test battery conducted a week after exposure, all measures showed recovery to pre-exposure values.

Queixas auditivas de disc jockeys da cidade de Recife

OBJETIVO: investigar a ocorrência de queixas auditivas em disc jockeys da cidade de Recife/PE. MÉTODOS: foi realizada uma entrevista com 30 disc jockeys, com idade entre 19 e 28 anos, abordando informações ocupacionais, conhecimentos gerais sobre o ruído e queixas auditivas (diminuição da acuidade auditiva, desconforto a sons intensos, zumbido, sensação de ouvido abafado e otalgia). A análise foi realizada por meio de abordagem quantitativa, utilizando o teste estatístico t-student. RESULTADOS: dentre os dados mais relevantes, destacam-se: 46,7% dos disc jockeys apresentaram, espontaneamente, queixas auditivas, em especial, a diminuição da acuidade auditiva (relatada por todos os sujeitos); 14 disc jockeys (46,67%) referiram desconforto a sons intensos e 13 (43,33%) mencionaram zumbido. Todos afirmaram ter conhecimento sobre os riscos do ruído para a saúde auditiva, mas 76,7% não realizam qualquer medida preventiva de suas consequências. A perda auditiva foi referida pelos sujeitos como o principal risco da exposição a níveis intensos de pressão sonora. CONCLUSÃO: todos os disc jockeys apresentaram queixa de perda auditiva e, entre as demais queixas auditivas, destacaram-se o desconforto a sons intensos e o zumbido. Tendo em vista a irreversibilidade da perda auditiva induzida por elevados níveis de pressão sonora, os disc jockeys devem ser periodicamente avaliados a fim de que se confirme ou não a perda auditiva de que se queixaram e, caso ela exista, deve ser monitorada para que seja passível de intervenção pelo fonoaudiólogo. Desta forma, percebe-se a necessidade de atuação da Fonoaudiologia junto aos disc jockeys, uma vez que poder-se-á propiciar a otimização do exercício profissional com o mínimo de risco possível.

The risks of amplified music for disc-jockeys working in nightclubs

OBJECTIVES

Here, we evaluate the risks of amplified music for disc-jockeys (DJs) working in nightclubs.

DESIGN

Sound level measurements were performed within the DJ mixing booths. A questionnaire was used to obtain exposure to noise and length of time in the profession. Audiograms and tinnitus pitch matching was also performed.

RESULTS

The DJs' audiograms showed the expected noise-induced hearing loss at 6 KHz, but also low frequency losses at 125-500 Hz. Three quarters of them have tinnitus with a frequency corresponding to hearing loss.

CONCLUSIONS

This study highlights the risk of amplified music on hearing and tinnitus.

[Study of the hearing of rock and roll musicians]

BACKGROUND

rock and roll has as one of its main characteristics the excessive sound pressure levels. Several studies have demonstrated that the sound levels of rock concerts can range from 100 to 115dB (A), with peak levels of 150dB (A).

AIM

to study the hearing of rock and roll musicians, analyzing the results of the audiological evaluation and verifying the influence of time of exposure to amplified music.

METHOD

a questionnaire was answered by 23 rock and roll musicians (46 ears) who were also evaluated by means of pure tone audiometry, immitance audiometry and transient/distortion product evoked otoacoustic emissions (OAET and OAEPD).

RESULTS

regarding the time of exposure to music, values close to the limit of acceptance (tending to be significants) were found in the frequencies of 0.5 and 6kHz, in the pure tone audiometry. A statistically significant difference was also found in the OAET test in the frequency of 2kHz and also in the frequencies of 0.75, 1, 4 and 6kHz in the OAEPD test.

CONCLUSION

the results indicate that although hearing loss was not found in the studied population, alteration in the register of the OAE already exists, suggesting alteration of the cochlear function. Regarding time of exposure, the results indicate that musicians with more than 10 years of practice present statistically significant differences when compared to those with less time of exposure.

Prevalence of high frequency hearing loss consistent with noise exposure among people working with sound systems and general population in Brazil: a cross-sectional study

BACKGROUND

Music is ever present in our daily lives, establishing a link between humans and the arts through the senses and pleasure. Sound technicians are the link between musicians and audiences or consumers. Recently, general concern has arisen regarding occurrences of hearing loss induced by noise from excessively amplified sound-producing activities within leisure and professional environments. Sound technicians' activities expose them to the risk of hearing loss, and consequently put at risk their quality of life, the quality of the musical product and consumers' hearing. The aim of this study was to measure the prevalence of high frequency hearing loss consistent with noise exposure among sound technicians in Brazil and compare this with a control group without occupational noise exposure.

METHODS

This was a cross-sectional study comparing 177 participants in two groups: 82 sound technicians and 95 controls (non-sound technicians). A questionnaire on music listening habits and associated complaints was applied, and data were gathered regarding the professionals' numbers of working hours per day and both groups' hearing complaint and presence of tinnitus. The participants' ear canals were visually inspected using an otoscope. Hearing assessments were performed (tonal and speech audiometry) using a portable digital AD 229 E audiometer funded by FAPESP.

RESULTS

There was no statistically significant difference between the sound technicians and controls regarding age and gender. Thus, the study sample was homogenous and would be unlikely to lead to bias in the results. A statistically significant difference in hearing loss was observed between the groups: 50% among the sound technicians and 10.5% among the controls. The difference could be addressed to high sound levels.

CONCLUSION

The sound technicians presented a higher prevalence of high frequency hearing loss consistent with noise exposure than did the general population, although the possibility of residual confounding due to unmeasured factors such as socioeconomic status cannot be ruled out.

Ototoxicity and noise trauma: electron transfer, reactive oxygen species, cell signaling, electrical effects, and protection by antioxidants: practical medical aspects

Ototoxins are substances of various structures and classes. This review provides extensive evidence for involvement of electron transfer (ET), reactive oxygen species (ROS) and oxidative stress (OS) as a unifying theme. Successful application is made to the large majority of ototoxins, as well as noise trauma. We believe it is not coincidental that these toxins generally incorporate ET functionalities (quinone, metal complex, ArNO(2), or conjugated iminium) either per se or in metabolites, potentially giving rise to ROS by redox cycling. Some categories, e.g., peroxides and noise, appear to operate via non-ET routes in generating OS. These highly reactive entities can then inflict injury via OS upon various constituents of the ear apparatus. The theoretical framework is supported by the extensive literature on beneficial effects of antioxidants, both for toxins and noise. Involvement of cell signaling and electrical effects are discussed. This review is the first comprehensive one based on a unified mechanistic approach. Various practical medical aspects are also addressed. There is extensive documentation for beneficial effects of antioxidants whose use might be recommended clinically for prevention of ototoxicity and noise trauma. Recent research indicates that catalytic antioxidants may be more effective. In addition to ototoxicity, a widespread problem consists of ear infections by bacteria which are demonstrating increasing resistance to conventional therapies. A recent, novel approach to improved drugs involves use of agents which inhibit quorum sensors that play important roles in bacterial functioning. Prevention of ear injury by noise trauma is also discussed, along with ear therapeutics.

Intercorrência audiológica em músicas após um show de rock

OBJETIVO: verificar mudança temporária do limiar de audição de músicos, após exposição a níveis de pressão sonora elevados de um show de rock. MÉTODOS: foi utilizada uma amostra com seis músicos componentes da banda. Foram feitos: anamnese ocupacional, determinação dos níveis mínimos de audição e reflexos acústicos, antes e após o show de rock. A mensuração do ruído da sala do exame e do palco foi realizada por meio de um dosímetro. Os resultados foram comparados e analisados estatisticamente, utilizando-se o teste t Student, com critério para determinação de significância de p maior do que 0,05. RESULTADOS: para a dosimetria, foi encontrada a exposição ao ruído do show com valor de LAVG igual a 98,5 dB. Dentre os aspectos comportamentais relacionados ao ruído, o zumbido foi a queixa mais presente entre os integrantes. Na audiometria tonal, as maiores diferenças pré e pós-exposição, foram encontradas nas freqüências altas, sendo a orelha direita a que apresentou maiores mudanças temporárias de limiar. Os resultados foram significantes nas freqüências de 2000, 3000, 4000 e 6000 Hz, na orelha direita (p=2,7; p=2,59; p=3,7 e p=2,86) e, na freqüência de 4000 Hz, na orelha esquerda (p=2,87). Na medida do reflexo acústico após o show, a orelha direita obteve o maior índice de ausência de reflexo, com o índice de 40%; entretanto, foram encontradas diferenças estatisticamente significantes, na presença de reflexo acústico na comparação pré e pós-exposição, apenas na orelha esquerda (p=3,64). CONCLUSÃO: músicos expostos a níveis de pressão sonora intensos apresentaram alteração temporária do limiar e alteração do reflexo acústico.

Music exposure and audiological findings in Brazilian disc jockeys (DJs)

The aim of this study was to examine the music exposure and hearing of disc jockeys (DJs). We conducted personal noise dosimetry on 30 DJs and interviewed them regarding their hearing and their job. We conducted pure-tone audiometry, and transient and distortion product otoacoustic emissions before their exposure to music during their work. This first test was preceded by a period of at least 12 hours without exposure to music or noise. We repeated the pure-tone audiometry and otoacoustic emissions after their music exposure, and poorer performances were registered in all retests. The nightclubs' average sound level ranged between 93.2 to 109.7 dB(A). Statistical analysis showed significant bilateral temporary threshold shifts at all frequencies between audiometry performed pre- and post-exposure to amplified music. Transient otoacoustic emissions showed a significant difference in bilateral amplitude and reproducibility at all frequency bands tested. The comparison of distortion product otoacoustic emissions results pre- and post-music exposure showed there was a significant difference in amplitude. Music exposure was associated with temporary and permanent auditory dysfunction among professional DJs.

Plasma antibodies to heat shock protein 60 and heat shock protein 70 are associated with increased risk of electrocardiograph abnormalities in automobile workers exposed to noise

In the living and working environment, stressful factors, such as noise, can cause health problems including cardiovascular diseases and noise-induced hearing loss. Some heat shock proteins (Hsps) play an important role in protecting cardiac cells against ischemic injury, and antibodies against these Hsps are associated with the development and prognosis of atherogenesis, coronary heart disease, and hypertension. Whether the presence of such antibodies is associated with abnormal electrocardiography (ECG) in stressed autoworkers exposed to chronic noise is presently unknown. Therefore, we investigated the association between the levels of plasma anti-Hsp60 and anti-Hsp70 with electrocardiograph abnormality in 396 autoworkers exposed to different noise levels by using Western blot, ECG, and multivariate logistic regression analysis. The results showed that the increase in levels of anti-Hsp70 was associated with a higher risk of ECG abnormalities characteristic of chronic myocardial ischemia (P < 0.05), conductive abnormality (P < 0.01), or heart displacement (P < 0.05); in contrast, elevated anti-Hsp60 was related to ECG abnormalities characteristic of sinus arrhythmia, chronic myocardial ischemia, and ectopic rhythm (P < 0.01 for all). Overall, high levels of both anti-Hsp70 and anti-Hsp60 were associated with significantly increased risk of ECG abnormalities (odds ratio [OR] = 1.73 and 95% confidence interval [Cl] = 1.04-2.86 for anti-Hsp70 and OR = 1.36 and 95% Cl = 1.07-1.72 for anti-Hsp60) with and without adjustment for cumulative noise exposure (OR = 1.96 and 95% Cl = 1.20-3.21 for anti-Hsp70 and OR = 3.93 and 95% Cl = 1.72-8.92 for anti-Hsp60). These findings suggest that the production of both anti-Hsp70 and anti-Hsp60 may be independent risk factors for the development and progression of abnormal ECG and therefore possibly cardiovascular diseases in autoworkers exposed to occupational noise.