Noise and hearing loss: a review

Acute stress induces hyperacusis in women with high levels of emotional exhaustion

Background

Hearing problems is one of the top ten public health disorders in the general population and there is a well-established relationship between stress and hearing problems. The aim of the present study was to explore if an acute stress will increase auditory sensitivity (hyperacusis) in individuals with high levels of emotional exhaustion (EE).

Methods

Hyperacusis was assessed using uncomfortable loudness levels (ULL) in 348 individuals (140 men; 208 women; age 23–71 years). Multivariate analyses (ordered logistic regression), were used to calculate odds ratios, including interacting or confounding effects of age, gender, ear wax and hearing loss (PTA). Two-way ANCOVAs were used to assess possible differences in mean ULLs between EE groups pre- and post-acute stress task (a combination of cold pressor, emotional Stroop and Social stress/video recording).

Results

There were no baseline differences in mean ULLs between the three EE groups (one-way ANOVA). However, after the acute stress exposure there were significant differences in ULL means between the EE-groups in women. Post-hoc analyses showed that the differences in mean ULLs were between those with high vs. low EE (range 5.5–6.5 dB). Similar results were found for frequencies 0.5 and 1 kHz. The results demonstrate that women with high EE-levels display hyperacusis after an acute stress task. The odds of having hyperacusis were 2.5 (2 kHz, right ear; left ns) and 2.2 (4 kHz, right ear; left ns) times higher among those with high EE compared to those with low levels. All these results are adjusted for age, hearing loss and ear wax.

Conclusion

Women with high levels of emotional exhaustion become more sensitive to sound after an acute stress task. This novel finding highlights the importance of including emotional exhaustion in the diagnosis and treatment of hearing problems.

The prevention of noise induced hearing loss in children

Increasingly, our acoustic environment is filled with amplified sound sources (e.g., MP3 players, video game stations, and sports/entertainment venues). There is serious concern and also some controversy about the risks of acoustic trauma in children. This overview provides some basic information on the physiological mechanisms that lead to noise induced hearing loss, a survey of various studies that, on balance, indicates that there is cause for concern, and finally a discussion on measures that can help to prevent noise induced hearing loss in children. This paper is designed for public health and other healthcare professions (ENT, audiologists, family doctors, and pediatricians) who should understand the risks of noise induced hearing loss and its prevention.

"Epic Ear Defence"-A Game to Educate Children on the Risks of Noise-Related Hearing Loss

Hearing loss resulting from overexposure to entertainment-related sounds is a modern concern. "Epic Ear Defence" places the player in the three-dimensional environment of the ear canal and challenges the player to defend the ear from various noises, to delay the onset of noise-related hearing loss.

A suggested model for decision-making regarding hearing conservation: towards a systems theory approach

OBJECTIVE

The aim of the study was to investigate potential health promotion variables associated with adolescents' hearing protection use at concerts.

STUDY SAMPLE

The sample consisted of 242 upper secondary school students aged 15-19 years.

DESIGN

Variables defined by the theory of planned behaviour (TBP) and health belief model were tested in this quantitative study.

RESULTS

Fifty-three percent of the adolescents reported that they used hearing protection at concerts to some degree, and 33 individuals (14%) reported that they used hearing protection in 50% of cases or more. The average degree of hearing protection use was reported to be 17% of the visits at concerts. Norms, perceived control, barriers, and noise sensitivity were associated with attitudes towards loud music. In addition, norms, barriers, permanent tinnitus, and noise sensitivity were significantly correlated with hearing protection use. However, intention was not significantly correlated with hearing protection use.

CONCLUSIONS

From a systems theoretical approach it can be suggested that preventive strategies must consider more levels than just the individual, in order to achieve long lasting behavioural changes in adolescents' listening habits. To be able to get useful knowledge about preventive strategies, it is necessary to add context-specific variables into generic models such as TPB.

Análise acústica em brinquedos ruidosos

OBJETIVO: analisar os níveis de ruídos emitidos por brinquedos nacionalmente comercializados, utilizados por crianças de 1 a 5 anos; comparar os valores entre os brinquedos com e sem selo do Inmetro (Instituto Nacional de Metrologia, Normalização e Qualidade Industrial) e analisar o espectro acústico dos brinquedos, com o intuito de identificar a área da cóclea que pode ser mais afetada por esses ruídos. MÉTODO: as medições foram realizadas em 20 brinquedos sonoros (10 com o selo do Inmetro e 10 sem o selo) com o uso do decibelímetro digital em sala acusticamente tratada, e a análise dos sons emitidos pelos brinquedos foi realizada por meio do programa Praat. RESULTADOS: a intensidade do ruído dos brinquedos com o selo do Inmetro posicionados a 2,5 cm do equipamento variou de 61,50 a 91,55 dB(A) e 69,75 a 95,05 dB(C) e a referente à distância de 25 cm variou entre 58,30 a 79,85 dB(A) e 62,50 a 83,65 dB(C). A intensidade do ruído dos brinquedos sem o selo do Inmetro a 2,5 cm variou entre 67,45 a 94,30 dB(A) e 65,4 a 99,50 dB(C) e na distância de 25 cm registrou desde 61,30 a 87,45 dB(A) e 63,75 a 97,60 dB(C), portanto os achados demonstraram que existem brinquedos ruidosos que ultrapassam os valores recomendados pela legislação vigente em ambos os grupos, com e sem selo do Inmetro. CONCLUSÃO: os brinquedos sem o selo do Inmetro apresentaram valores de intensidade significantemente maior em relação ao outro grupo, oferecendo maior risco à saúde auditiva das crianças.

Characteristics of noise-canceling headphones to reduce the hearing hazard for MP3 users

Three pairs of headphones [standard iPod ear buds and two noise-canceling headphones (NCHs)] were chosen to investigate frequency characteristics of noise reduction, together with their attenuation effects on preferred listening levels (PLLs) in the presence of various types of background noise. Twenty-six subjects with normal hearing chose their PLLs in quiet, street noise, and subway noise using the three headphones and with the noise-canceling system on/off. Both sets of NCHs reduced noise levels at mid- and high-frequencies. Further noise reductions occurred in low frequencies with the noise canceling system switched on. In street noise, both NCHs had similar noise reduction effects. In subway noise, better noise reduction effects were found in the expensive NCH and with noise-canceling on. A two way repeated measures analysis of variance showed that both listening conditions and headphone styles were significant influencing factors on the PLLs. Subjects tended to increase their PLLs as the background noise level increased. Compared with ear buds, PLLs obtained from NCHs-on in the presence of background noise were reduced up to 4 dB. Therefore, proper selection and use of NCHs appears beneficial in reducing the risk of hearing damage caused by high music listening levels in the presence of background noise.

[What is a "poison"? Proposal of definition]

We discuss different interpretations of the term poison as well as the need of bringing up to date the changes in this matter according to the science progress. A clear and exact definition is proposed after analysing the factors that affect the relativity of the concept and its boundaries. The proposal for a definition is presented taking into account the most broadly extended concepts concerning its significance. That is to say: "a poison is, for human beings and their non-pathogenic and non-harmful biological environment, an electromagnetic or corpuscular radiation, or a non-infectious chemical agent, structured no larger in size than a small particle or fibre that, after being generated internally or after contact, penetration and/or absorption by a live organism, in sufficiently high dose, can produce or produces a direct or indirect adverse effect unrelated to its temperature or measurable electrical potential difference". The scientific knowledge needs accurate definitions to avoid ambiguities.

Alleles that modulate late life hearing in genetically heterogeneous mice

A genetically heterogeneous population of mice was tested for hearing at 8, 18, and 22 months by auditory brainstem response (ABR), and genotyped at 128 markers to identify loci that modulate late life hearing loss. Half of the test mice were exposed to noise for 2 hours at age 20 months. Polymorphisms affecting hearing at 18 months were noted on chromosomes 2, 3, 7, 10, and 15. Most of these loci had effects only on responses to 48 kHz stimuli, but a subset also influenced the auditory brainstem response at lower frequencies. Loci on chromosomes 4, 10, 12, and 14 had significant effects on hearing at 22 months in noise-exposed mice, and loci on chromosomes 10 and 11 had effects on mice not exposed to noise. Outer hair cell loss was modulated by polymorphisms on chromosomes 10, 11, 12, 17, and 19. Resistance to age-related hearing loss is thus modulated by a set of genetic effects, some age-specific, some frequency specific, some dependent on prior exposure to noise, and some of which compromise survival of cochlear hair cells.

Involuntary and persistent environmental noise influences health and hearing in Beirut, Lebanon

Objective. This study was conducted to assess the effects of involuntary and persistent noise exposure on health and hearing among Lebanese adults in Beirut, Lebanon, where people are exposed to noise from construction sites, power generators, honking cars, and motorcycles. Methods. Using a descriptive and exploratory design with mixed methods, participants were surveyed, interviewed, and tested for hearing while street noise levels were measured near their residents and work places. Results. Self-reports of 83 Lebanese adult, who lived and worked in Beirut, helped identify common patterns in experiences such as irritability, anger, headaches, and sleep disturbances due to noise annoyance. Of those tested, 30% suffered from high-frequency hearing impairment. Our results showed that environmental sound dB had increased by 12% and sound intensity by 400% above the maximum standard level when compared to the WHO report of 1999. Conclusion. Environmental noise contributes to premature hearing loss and potentiates systemic diseases among Lebanese.

Temporary off-frequency listening after noise trauma

Hearing loss is routinely estimated from the audiogram, even though this measure gives only a rough approximation of hearing. Indeed, cochlear regions functioning poorly, if at all, called dead regions, are not detected by a simple audiogram. To detect cochlear dead regions, additional measurements of psychophysical tuning curves or thresholds in background noise (TEN test) are required. A first aim of this study was to assess the presence of dead regions after impulse noise trauma using psychophysical tuning curves. The procedure we used was based on a compromise between the need to collect reliable estimates of psychophysical tuning curves and the limited time available to obtain these estimates in a hospital setting. Psychophysical tuning curves were measured using simultaneous masking with a 2-alternative forced choice paradigm, where the target was randomly placed in one of the two masker presentations. It is well known that some components of noise-induced hearing loss are reversible. A second aim of this study was to examine the potential recovery of dead regions after acoustic trauma. A third issue addressed in this article was the relationship between noise-induced dead regions and tinnitus. We found that 70% of the subjects had dead regions after noise trauma, while 88% reported tinnitus. Moreover, we found that the extent of dead regions probably diminished in about 50% of subjects, which highlights the ability of the human auditory system to recover from noise-induced hearing loss.

Clinical characteristics of acoustic trauma caused by gunshot noise in mass rifle drills without ear protection

One of the major occupational hazards of working in military service is being subjected to intense impulse noise. We analyzed the clinical presentation of acoustic traumas, induced by mass rifle gunshot noise during military training, in unprotected patients. We evaluated 189 soldiers who had otologic symptoms after rifle shooting exercises without using any hearing protection. All soldiers had been training on the K2 rifle. We took medical histories; conducted physical examinations and hearing evaluations (pure-tone audiometry, speech audiometry, and impedence audiometry); and distributed the Newmann's Tinnitus Handicap Inventory (THI) survey. In addition, we evaluated a normal control group of 64 subjects of similar age who had never fired a rifle. In the patient group, the most common and irritating reported symptom was tinnitus (94.2%), and the average THI score in the patient group was 39.51 ± 14.87, which was significantly higher than the control group score (0.56 ± 3.94) (p < 0.001). Average outcomes of post-exposure air conduction thresholds were 21.33 ± 13.25 dB HL in the affected ears. These levels also were significantly higher than those of the control group (9.16 ± 4.07dB HL) (p < 0.001). Hearing loss was most prominent at high frequencies. An asymmetry of hearing loss related to head position during shooting was not observed. Acoustic trauma induced by gunshot noise can cause permanent tinnitus and hearing loss. Hearing protection (bilateral earplugs) and environmental reform are necessary.

The cochlear CRF signaling systems and their mechanisms of action in modulating cochlear sensitivity and protection against trauma

A key requirement for encoding the auditory environment is the ability to dynamically alter cochlear sensitivity. However, merely attaining a steady state of maximal sensitivity is not a viable solution since the sensory cells and ganglion cells of the cochlea are prone to damage following exposure to loud sound. Most often, such damage is via initial metabolic insult that can lead to cellular death. Thus, establishing the highest sensitivity must be balanced with protection against cellular metabolic damage that can lead to loss of hair cells and ganglion cells, resulting in loss of frequency representation. While feedback mechanisms are known to exist in the cochlea that alter sensitivity, they respond only after stimulus encoding, allowing potentially damaging sounds to impact the inner ear at times coincident with increased sensitivity. Thus, questions remain concerning the endogenous signaling systems involved in dynamic modulation of cochlear sensitivity and protection against metabolic stress. Understanding endogenous signaling systems involved in cochlear protection may lead to new strategies and therapies for prevention of cochlear damage and consequent hearing loss. We have recently discovered a novel cochlear signaling system that is molecularly equivalent to the classic hypothalamic-pituitary-adrenal (HPA) axis. This cochlear HPA-equivalent system functions to balance auditory sensitivity and susceptibility to noise-induced hearing loss, and also protects against cellular metabolic insults resulting from exposures to ototoxic drugs. We review the anatomy, physiology, and cellular signaling of this system, and compare it to similar signaling in other organs/tissues of the body.

Indoor environment and children's health: recent developments in chemical, biological, physical and social aspects

Much research is being carried out into indoor exposure to harmful agents. This review focused on the impact on children's health, taking a broad approach to the indoor environment and including chemical, microbial, physical and social aspects. Papers published from 2006 onwards were reviewed, with regards to scientific context. Most of publications dealt with chemical exposure. Apart from the ongoing issue of combustion by-products, most of these papers concerned semi volatile organic compounds (such as phthalates). These may be associated with neurotoxic, reprotoxic or respiratory effects and may, therefore, be of particular interest so far as children are concerned. In a lesser extent, volatile organic compounds (such as aldehydes) that have mainly respiratory effects are still studied. Assessing exposure to metals is still of concern, with increasing interest in bioaccessibility. Most of the papers on microbial exposure focused on respiratory tract infections, especially asthma linked to allergens and bio-aerosols. Physical exposure includes noise and electromagnetic fields, and articles dealt with the auditory and non auditory effects of noise. Articles on radiofrequency electromagnetic fields mainly concerned questions about non-thermal effects and papers on extremely low-frequency magnetic fields focused on the characterization of exposure. The impact of the indoor environment on children's health cannot be assessed merely by considering the effect of these different types of exposure: this review highlights new findings and also discusses the interactions between agents in indoor environments and also with social aspects.

Sound exposure of symphony orchestra musicians

BACKGROUND

Assessment of sound exposure by noise dosimetry can be challenging especially when measuring the exposure of classical orchestra musicians where sound originate from many different instruments. A new measurement method of bilateral sound exposure of classical musicians was developed and used to characterize sound exposure of the left and right ear simultaneously in two different symphony orchestras.

OBJECTIVES

To measure binaural sound exposure of professional classical musicians and to identify possible exposure risk factors of specific musicians.

METHODS

Sound exposure was measured with microphones mounted on the musician's ears and recorded digitally. The recorded sound was analysed and the specific sound exposure of the left and the right ear was determined for the musicians. A total of 114 measurements covering 106 h were recorded in two symphony orchestras.

RESULTS

Sound exposure depends significantly on the specific instrument and the repertoire played by the exposed musician. Concerts, group rehearsals and individual practice were all significant contributors to the sound exposure. The highest L(Aeq) of 86 -98 dB was found among the brass players. High string players were exposed from 82 to 98 dBA and their left ear was exposed 4.6 dB more than the right ear. Percussionists were exposed to high sound peaks >115 dBC but less continuous sound exposure was observed in this group. Musicians were exposed up to L(Aeq8h) of 92 dB and a majority of musicians were exposed to sound levels exceeding L(Aeq8h) of 85 dB.

CONCLUSIONS

Binaural recording of the individual sound exposure showed that orchestra musicians could be exposed differently to the left and right ear and that they were primarily exposed from their own instruments. Specific repertoires as well as the specific instrument determine the level of exposure.

Noise-induced hearing loss in children: A 'less than silent' environmental danger

A review of the problems of noise-induced hearing loss in children, especially related to recreational music and the use of personal entertainment devices. The pathophysiology of noise-induced hearing loss and its associated problems (eg, tinnitus) are discussed. The evidence for an increase in noise-induced hearing loss in children and young people is reviewed. Some practical advice (for clinicians, caregivers and children) on hearing loss prevention is provided.

Noise exposure estimates of urban MP3 player users

PURPOSE

To examine the sound level and duration of use of personal listening devices (PLDs) by 189 college students, ages 18-53 years, as they entered a New York City college campus, to determine whether noise exposure from PLDs was in excess of recommended exposure limits and what factors might influence exposure.

METHOD

Free-field equivalent sound levels from PLD headphones were measured on a mannequin with a calibrated sound level meter. Participants reported demographic information, whether they had just come off the subway, the type of PLD and earphones used, and duration per day and days per week they used their PLDs.

RESULTS

Based on measured free-field equivalent sound levels from PLD headphones and the reported PLD use, per day 58.2% of participants exceeded 85 dB A-weighted 8-hr equivalent sound levels (L(Aeq)), and per week 51.9% exceeded 85 dB A-weighted 40-hr equivalent continuous sound levels (L(Awkn)).

CONCLUSIONS

The majority of PLD users exceeded recommended sound exposure limits, suggesting that they were at increased risk for noise-induced hearing loss. Analyses of the demographics of these participants and mode of transportation to campus failed to indicate any particular gender differences in PLD use or in mode of transportation influencing sound exposure.

Emerging treatments for noise-induced hearing loss

INTRODUCTION

Approximately 5% of the population worldwide suffers from industrial, military or recreational noise-induced hearing loss (NIHL) at a great economic cost and detriment to the quality of life of the affected individuals. This review discusses pharmacological strategies to attenuate NIHL that have been developed in animal models and that are now beginning to be tested in field trials.

AREAS COVERED

The review describes the epidemiology, pathology and pathophysiology of NIHL in experimental animals and humans. The underlying molecular mechanisms of damage are then discussed as a basis for therapeutic approaches to ameliorate the loss of auditory function. Finally, studies in military, industrial and recreational settings are evaluated. Literature was searched using the terms 'noise-induced hearing loss' and 'noise trauma'.

EXPERT OPINION

NIHL, in principle, can be prevented. With the current pace of development, oral drugs to protect against NIHL should be available within the next 5-10 years. Positive results from ongoing trials combined with additional laboratory tests might accelerate the time from the bench to clinical treatment.

Overexpression of X-linked inhibitor of apoptosis protein protects against noise-induced hearing loss in mice

Apoptosis is responsible for cochlear cell death induced by noise. Here, we show that transgenic (TG) mice that overexpress X-linked inhibitor of apoptosis protein (XIAP) under control of the ubiquitin promoter display reduced hearing loss and cochlear damage induced by acoustic overstimulation (125 dB sound pressure level, 6 h) compared with wild-type (WT) littermates. Hearing status was evaluated using the auditory brainstem response (ABR), whereas cochlear damage was assessed by counts of surviving hair cells (HCs) and spiral ganglion neurons (SGNs) as well as their fibers to HCs. Significantly smaller threshold shifts were found for TG mice than WT littermates. Correspondingly, the TG mice also showed a reduced loss of HCs, SGNs and their fibers to HCs. HC loss was limited to the basal end of the cochlea that detects high frequency sound. In contrast, the ABRs demonstrated a loss of hearing sensitivity across the entire frequency range tested (2-32 kHz) indicating that the hearing loss could not be fully attributed to HC loss alone. The TG mice displayed superior hearing sensitivity over this whole range, suggesting that XIAP overexpression reduces noise-induced hearing loss not only by protecting HCs but also other components of the cochlea.

Prevalence of noise-induced hearing-threshold shifts and hearing loss among US youths

OBJECTIVE

We investigated trends in noise-induced threshold shifts (NITSs), high-frequency hearing loss (HFHL), and low-frequency hearing loss (LFHL).

METHODS

A total of 4310 adolescents 12 to 19 years of age completed audiometric testing during National Health and Nutrition Examination Surveys in 1988-1994 and 2005-2006. NITS criteria were audiometric patterns of decreased 3- to 6-kHz thresholds but preserved 0.5- to 1-kHz and 8-kHz thresholds; HFHL and LFHL criteria were high and low pure-tone averages, respectively, of >15 dB HL.

RESULTS

There were no significant increases in NITSs (odds ratio [OR]: 0.81 [95% confidence interval [CI]: 0.53-1.22]; P = .29), HFHL (OR: 1.21 [95% CI: 0.87-1.69]; P = .25), or LFHL (OR: 1.37 [95% CI: 0.77-2.45]; P = .28) between survey periods. However, a significant increase in the prevalence of NITSs occurred among female youths (11.6% [95% CI: 9.0%-14.1%] vs 16.7% [95% CI: 13.2%-20.3%]; P < .0001). The overall prevalence of exposure to loud noise or listening to music through headphones in the previous 24 hours increased from 19.8% (95% CI: 17.6%-22.1%) to 34.8% (95% CI: 31.0%-38.5%; P < .0001). In 2005-2006, female youths had a similar prevalence of exposure to recreational noise (23.6% [95% CI: 19.6%-27.6%] vs 27.7% [95% CI: 23.6%-31.8%]; P < .0001) and a lower prevalence of hearing-protection use (3.4% [95% CI: 1.6%-5.3%] vs 10.3% [95% CI: 7.3%-13.2%]; P < .0001) compared with male youths.

CONCLUSIONS

Increased exposure to recreational noise and minimal use of hearing protection might have lead to an increase in NITS prevalence among female youths.

Noise levels in a neonatal transport incubator in medically configured aircraft

OBJECTIVE

The purpose of this study was to evaluate exposure of neonates to noise during air medical transport as few commercially available hearing protective devices exist for premature newborns during air medical transport.

METHODS

Sound pressure levels in an infant incubator during actual flight conditions in four common medically configured aircraft were measured. Three noise dosimeters measured time-weighted average noise exposure during flight in each aircraft. One dosimeter was placed in the infant incubator, and the remaining dosimeters recorded noise levels in various parts of the aircraft cabin.

RESULTS

The incubator provided a 6-dBA decrease in noise exposure from that in the crew cabin. The average noise level in the incubator in all aircraft was close to 80 dB, much higher than the proposed limits of 45 dB for neonatal intensive care unit noise exposure or 60 dB during transport.

CONCLUSIONS

Exposure of neonates to elevated noise levels during transport may be harmful, and steps should be taken to protect the hearing of this patient population.

MP3 player listening habits of 17 to 23 year old university students

This study evaluated the potential risk to hearing associated with the use of portable digital audio players. Twenty-eight university students (12 males, 16 females; aged 17-23) completed a 49-item questionnaire assessing user listening habits and subjective measures of hearing health. Sound level measurements of participants' self-identified typical and 'worst case' volume levels were taken in different classrooms with background sound levels between 43 and 52 dBA. The median frequency and duration of use was 2 h per day, 6.5 days a week. The median sound levels and interquartile ranges (IQR) at typical and 'worst case' volume settings were 71 dBA (IQR=12) and 79 dBA (IQR=9), respectively. When typical sound levels were considered with self-reported duration of daily use, none of the participants surpassed Leq(8) 85 dBA. On the questionnaire, 19 students reported experiencing at least one symptom of possible noise-induced hearing loss. Significant differences in MP3 user listening patterns were found between respondents who had experienced tinnitus and those who had not. The findings add to a growing body of literature that collectively supports a need for further research investigating MP3 player user listening habits in order to assess their potential risk to hearing health.

Prevalence and Risk Factors of Hearing Impairment Among Primary-School Children in Shebin El-Kom District, Egypt

Purpose

This study examined the feasibility of screening hearing loss in rural and urban schools in Egypt, and investigated the prevalence and causes of hearing impairment (HI) in Egyptian primary-school students.

Method

A total of 555 children (6–12 years of age) from a rural and an urban school in the Shebin El-Kom District of Egypt were screened for HI at their schools. A 2-stage screening procedure was used, and positive cases were referred for a diagnostic hearing assessment at a regional medical facility. Risk factors were investigated through a parent questionnaire and an environmental study consisting of noise, ventilation, and crowding measurements at the schools.

Results

The screening failure rate was 25.6%, and the prevalence of confirmed HI was 20.9%. The rate of HI did not differ across the schools. Conductive hearing loss of minimal to mild severity was the most common type of HI. The most important predictors for HI were parent suspicion, otitis media, household smoking, low socioeconomic status, and postnatal jaundice.

Conclusions

The prevalence of HI did not differ across settings and was more common than reported in children from developed countries. The screening results also suggest that professionals with limited audiology background can be trained to implement hearing screening programs in Egyptian schools.

Self-assessed auditory symptoms, noise exposure, and measured auditory function among healthy young Swedish men

The aim of the study was to estimate the prevalence of the exposure to ototraumatic factors and auditory symptoms, and to analyse the relations between these factors in a group of young healthy men. A total of 839 men, 19-22 years old, were recruited for the study when reporting for primary military service. A questionnaire was distributed and audiometry was performed. The prevalence of tinnitus, sensitivity to noise, and measured hearing impairment in the study group was 23.2%, 15.5%, and 14.5% respectively. Exposure to occupational noise often was reported by 21.4%, and playing loud music often by 16.5%. The young men who had experienced tinnitus after noise exposure had an elevated risk of high frequency hearing impairment, tinnitus, and sensitivity to noise. Those who played loud music had elevated prevalence values of tinnitus but not of hearing impairment. In this young group we observed high prevalence values of ototraumatic factors and auditory symptoms. We also observed significant correlations between tinnitus after noise exposure, self-assessed hearing symptoms, and hearing impairment.

Hearing problems among a cohort of nationally certified EMS professionals

PURPOSE

The objectives of this study were to estimate the prevalence of hearing problems among a national cohort of emergency medical service (EMS) professionals, determine factors associated with hearing problems, and estimate the percentage of EMS professionals who utilize hearing protection.

METHODS

Utilizing results from a questionnaire, individuals who reported hearing problems were compared to individuals who had not. Multivariable logistic regression was performed to identify variables associated with hearing problems. Finally, items regarding use of hearing protection were assessed to estimate the percentage of usage among EMS professionals.

RESULTS

In total, 1,058 (57%) participants responded to the questionnaire. Of those, 1,024 (97%) who completed the hearing problems question were utilized for analysis. There were 153 (14.9%) cases of self-reported hearing problems. The final logistic regression model included lifetime occupational noise exposure 0.99 (95% CI = 0.9997-1.0002), report of previous back problems (odds ratio (OR) = 2.74, 95% CI = 1.8340-4.1042), large community size (OR = 1.67, 95% CI = 1.1211-2.4843), and minority status (OR = 0.61, 95% CI = 0.3719-0.9867). Finally, 213 (20.8%) individuals reported utilizing some form of hearing protection at their main EMS job.

CONCLUSION

The results from this analysis are the first national estimates of the prevalence of self reported hearing problems among EMS professionals. This study was also the first to estimate the percentage of EMS professionals who self reported the utilization of hearing protection.

Hearing threshold of Korean adolescents associated with the use of personal music players

PURPOSE

Hearing loss can lead to a number of disabilities and can reduce quality of life. Noise-induced hearing losses have become more common among adolescents due to increased exposure to personal music players. We, therefore, investigated the use of personal music player among Korean adolescents and the relationship between hearing threshold and usage pattern of portable music players.

MATERIALS AND METHODS

A total of 490 adolescents were interviewed personally regarding their use of portable music players, including the time and type of player and the type of headphone used. Pure tone audiometry was performed in each subject.

RESULTS

Of the 490 subjects, 462 (94.3%) used personal music players and most of them have used the personal music player for 1-3 hours per day during 1-3 years. The most common type of portable music player was the MP3 player, and the most common type of headphone was the earphone (insert type). Significant elevations of hearing threshold were observed in males, in adolescents who had used portable music players for over 5 years, for those over 15 years in cumulative period and in those who had used earphones.

CONCLUSION

Portable music players can have a deleterious effect on hearing threshold in adolescents. To preserve hearing, adolescents should avoid using portable music players for long periods of time and should avoid using earphones.

Prevalence of hearing loss in Black and White elders: results of the Cardiovascular Health Study

PURPOSE

The goal of this study was to determine the impact of age, gender, and race on the prevalence and severity of hearing loss in elder adults, aged 72-96 years, after accounting for income, education, smoking, and clinical and subclinical cardiovascular disease. Methods Air-conduction thresholds for standard and extended high-frequency pure-tones were obtained from a cohort of 548 (out of 717) elderly adults (ages 72-96 years) who were recruited during the Year 11 clinical visit (1999-2000) of the Cardiovascular Health Study (CHS) at the Pittsburgh, Pennsylvania site. Participant smoking, income, education, and cardiovascular disease histories were obtained from the CHS database and were included as factors.

RESULTS

Hearing loss was more common and more severe for the participants in their 80s than for those in their 70s-the men more than the women and the White participants more than the Black participants. The inclusion of education, income, smoking, and cardiovascular disease (clinical and subclinical) histories as factors did not substantively impact the overall results.

CONCLUSION

Although the data reported in this article were cross-sectional and a cohort phenomenon might have been operational, they suggested that hearing loss is more substantive in the 8th than the 7th decade of life and that race and gender influence this decline in audition. Given the high prevalence in the aging population and the differences across groups, there is a clear need to understand the nature and causes of hearing loss across various groups in order to improve prevention and develop appropriate interventions.

Subjective tinnitus and hearing problems in adolescents

OBJECTIVES

We investigated the hearing problems and tinnitus frequencies in adolescents at three public primary and two high schools.

METHODS

This study was carried out at three public primary and two high schools. 428 Turkish school children (244 girls, 184 boys) were asked to voluntarily answer a set of questionnaires in their classrooms at the beginning of the training program. There were 250 students (105 male, 145 female) in Primary School and 178 (79 male, 99 female) students in High School. We used questionnaire to evaluate subjective tinnitus and hearing problems. Walkman usage, listening loud and noisy music, intra-familial physical trauma, concentration difficulty in class and school success were also evaluated.

RESULTS

In age-related groups (Group 1=11-13 years; Group 2=13-15 years; Group 3=16-18 years), hearing loss was present in 32.1% of Group 1, 19% of Group 2 and 28.3% of Group 3. Listening loud and noisy music was reported in 81.8% of Group 1, 95.4% of Group 2 and 87% of Group 3. Tinnitus was present 36.8% in Group 2, 33.5% in Group 1 and 31.5% in Group 3. Tinnitus after listening loud music was present in 42.7% of Group 2, 36.1% of Group 3 and 25.6% of Group 1. Among all students with tinnitus, 19.5% considered their school success as very good, 41.1% as good and 39.4% as bad. In students, using Walkman, tinnitus was seen both in the right and left ears.

CONCLUSION

Tinnitus may be seen in adolescents at primary and high schools. Listening loud and noisy music and Walkman usage may cause an increase in the frequency of tinnitus manifestation. Adolescents should be educated about the hazardous effects of loud music. Education should include families, teachers, students, and whole community. These issues should be taken into public health policy of the countries.

Validity of self-reported occupational noise exposure

In all epidemiological studies the validity of self-reported questionnaire data is an important issue as the exposure assessment based on such data is a major source of bias in the risk estimation. A validation study was conducted based on a case-control study including 94 acoustic neuroma cases and 191 matched controls from the German Interphone Study to investigate the level of agreement between self-reported occupational noise exposure and a job-exposure-matrix (JEM) on noise exposure derived from a lifetime occupation calendar. The JEM was generated based on measurement data collected in the literature for various occupations. Level of agreement was investigated by using sensitivity, specificity, kappa coefficient and the Youden-Index. The receiver operating characteristics curve yielded an optimal cut point of 80 decibel(Acoustic) (dB(A)) to dichotomize noise exposure, displaying a moderate agreement between self-reported exposure and the JEM-based exposure (kappa of 0.53) that was slightly higher for cases than controls (kappas of 0.62 and 0.48). The agreement was only slightly lower if the longest held job or the last held job were used instead of the loudest job of the lifetime job history. The cut point of 80 dB(A) corresponds with regulations for workers safety with a recommendation to wear noise protection. The good levels of agreement between self-reported high occupational noise exposure compared with JEM-data, together with no substantial differences between cases and controls, suggest that self-reported data on occupational noise exposure is a valid exposure metric. Noise exposure appears to be appropriate if only exposure information on the last or the longest held job is available.

Diabetes impairs recovery from noise-induced temporary hearing loss

OBJECTIVES/HYPOTHESIS

The purpose of this study is to investigate whether diabetes impairs the recovery from noised-induced temporary hearing loss.

METHODS

Twenty-eight male Wistar rats were divided into three groups: control, diabetes with insulin control (DI), and diabetes without insulin control (DM). Diabetes was induced by intraperitoneal injection of streptozotocin. All animals were exposed to white noise at 110 dB SPL for 8 hours. Auditory brainstem response (ABR) thresholds and distortion product otoacoustic emission (DPOAE) amplitudes were measured for all animals 1 day prior to noise exposure to obtain a baseline for hearing function, and then 1 hour, 1 day, 2 days, 4 days, 7 days, and 14 days after noise exposure.

RESULTS

One hour post exposure, ABR thresholds shifted markedly, and DPOAE was reduced similarly in all groups. Both ABR thresholds and DPOAE returned to the baseline in the control group at day 1, but they were not back to the baseline in the DM group even by day 14. Compared with the control group, the ABR threshold shifts and DPOAE returned to baseline more slowly in the DI group.

CONCLUSIONS

The present study suggests that diabetic patients need proper blood sugar control and probably need more effective preventive measures to preserve their hearing from the effects of noise. Laryngoscope, 2009.

The effect of postnatal exposure to noise on sound level processing by auditory cortex neurons of rats in adulthood

Most people are exposed daily to some level and duration of environmental noise. The aim of the present study was to determine the effect of postnatal exposure to a moderate level of noise on sound level processing by neurons in the primary auditory cortex of rats in adulthood. The cortical neuron response to sound stimuli was investigated in three groups of rats. Two groups, either in the critical period of postnatal hearing development or in adulthood, were exposed to 80 dB SPL interrupted white noise for 8 h/day for 2 weeks. The control group consisted of adult rats that were not exposed to the white noise. Seven weeks later, the minimum threshold, the first spike latency, the dynamic range and the slope of the rate-level functions of cortical neuron response to a sound stimulus were determined. The cortical neurons in young rats exposed to the noise had a significantly higher minimum threshold, a longer first spike latency, a shorter dynamic range and a bigger slope in rate-level functions compared with the control group. The group in which adult rats were exposed to the white noise, however, did not have a significant change of sound level processing by the auditory cortical neurons. These results demonstrated that young rats were more susceptible to noise exposure affecting the cortical neuron processing of sound levels.

Can Rh antigens be a risk factor in noise-induced hearing loss?

Noise-induced hearing loss (NIHL) is one of the most common occupational problems and is one of the main causes of deafness. Many factors cause NIHL. Individual susceptibility is one of them. Rhesus (Rh) antigens and ABO blood groups can be factors in determining individual susceptibility. We aim to investigate the relationship between the Rh antigens and NIHL. The study was conducted in 438 factory workers who had been exposed to a noise level more than 85 dB for 8 h a day for a period of >/=15 years. The audiologic results and blood groups were obtained from the individual health records of the factory workers. We determined NIHL in 236 (53.9%) workers. Two hundred and nineteen (55.4%) of Rh-positive workers and seventeen (39.5%) of Rh-negative workers have NIHL, and the difference between the two groups was statistically significant (P < 0.05), whereas no statistically significant difference was determined between the NIHL and ABO blood groups. In conclusion, we suggest that the people with Rh-positive blood group are more prone to develop NIHL.

Evaluation of an internet-based hearing test--comparison with established methods for detection of hearing loss

Background

Hearing impairment is most accurately measured by a clinical pure-tone audiogram. This method is not suitable for large-scale, population-based epidemiological studies as it requires that study participants visit a clinic with trained personnel. An alternative approach to measuring hearing ability is self-estimation through questionnaires, but the correlation to clinical audiometric tests varies.

Objective

To evaluate an Internet-based hearing test pilot compared to a question about self-estimated hearing and the feasibility of using an Internet-based hearing test and an Internet-based questionnaire in a population of 560 members of the Swedish Hunters’ Association in the age group 20-60 years.

Methods

An invitation was mailed to the participants in March 2007 together with the URL to the study Web site, a personal username, and a password. The Web site included the questionnaire, the hearing test, and instructions for participating in the study. The hearing test resembles a clinical audiogram presenting 6 tones between 500 and 8000 Hz. Tones are presented between 0 and 60 dB, and the participant responds to the tones by pressing the space bar. The hearing test requires headphones and is based on JAVA programming. Before the participant can start the hearing test, it has to be calibrated against a reference person with good hearing between 15 and 35 years of age.

Results

After 5 months, 162 out of 560 (29%) had answered the questionnaire, out of which 88 (16%) had completed the hearing test. Those who actively declined participation numbered 230 out of 560 (41%). After removing duplicates and hearing tests calibrated by unreliable reference data, 61 hearing tests remained for analysis. The prevalence of hearing impairment from the Internet-based hearing test was 20% (12 out of 61), compared to 52% (32 out of 61) from the self-estimated question. Those who completed the hearing test were older than the non-participants, and more had headphones (P = .003) and the correct version of the JAVA program (P = .007) than those who only answered the questionnaire.

Conclusions

Though an Internet-based hearing test cannot replace a clinical pure-tone audiogram conducted by a trained audiologist, it is a valid and useful screening tool for hearing ability in a large population carried out at a low cost.

Noise exposure at young age impairs the auditory object exploration behavior of rats in adulthood

Environment noise is ubiquitous in our daily life. The aim of the present study was to determine the effect of postnatal exposure to moderate-level noise on the auditory object exploration behavior of adult rats by comparing the ability of three groups of rats to locate a sound source in a water maze. Two groups of rats, either in the critical period of hearing development or in adulthood, were exposed to 80 dB SPL interrupted white noise for 8 h per day for two weeks. The control group of rats was not exposed to the noise. The ability of the rats to locate a hidden platform that was situated near a sound source in a water maze was tested starting on postnatal day 77. A continuous improvement in the performance of control rats and rats exposed to noise in adulthood was observed during training, whereas rats exposed to noise at a young age exhibited a significantly worse performance. These findings indicated that long-term exposure of young rats to moderate-level noise caused significant impairment of their auditory object exploration behavior compared to exposure of adult animals to the same moderate-level noise.