Showing papers in "Noise & Health in 2005"

Factors affecting the use of hearing protectors among classical music players.

Abstract: Classical musicians are often exposed to sound levels that exceed the Finnish national action limit value of 85 dB(A). Still, the use of hearing protectors is uncommon among musicians. The purpose of this study was to find out musician's attitudes towards hearing protectors, and under which conditions hearing protectors are used. The study group consisted of five major classical orchestras in the Helsinki region. The players were asked to fill out a questionnaire with questions on hearing protection, ear symptoms, including tinnitus, hearing loss, pain in the ears, and temporary ringing in the ears. Also, questions concerning stress and working environments were asked. Of those who responded, 94% were concerned about their hearing to some degree. Only 6% of the musicians always used hearing protector devices (HPDs). Self-reported hearing loss was quite common, with 31% of the musicians reporting some hearing loss. Temporary tinnitus was even more common at 37%. There were 15% of women, and 18% of men reporting permanent tinnitus. Hyper-acousis was reported by 43% of the musicians. The ear symptoms affected the usage rate. Hearing protectors were used more often among musicians having ear symptoms (20%) than those reporting no symptoms (6%). Further, the 43% of the musicians found their work to be interesting and meaningful. Stress was experienced to some extent by 60%, and musicians with ear symptoms had three to nine times more stress and felt their working environment noisier. The study shows that musicians seldom use hearing protectors before symptoms begin. Symptoms increased usage rate, but the usage levels are still far from ideal. Motivation and training is needed to improve hearing protector use among musicians.

Noise annoyance in Canada.

Abstract: The present paper provides the results from two nation-wide telephone surveys conducted in Canada on a representative sample of 5,232 individuals, 15 years of age and older. The goals of this study were to gauge Canadians' annoyance towards environmental noise, identify the source of noise that is viewed as most annoying and quantify annoyance toward this principal noise source according to internationally accepted specifications. The first survey revealed that nearly 8% of Canadians in this age group were either very or extremely bothered, disturbed or annoyed by noise in general and traffic noise was identified as being the most annoying source. A follow-up survey was conducted to further assess Canadians' annoyance towards traffic noise using both a five-item verbal scale and a ten-point numerical scale. It was shown that 6.7% of respondents indicated they were either very or extremely annoyed by traffic noise on the verbal scale. On the numerical scale, where 10 was equivalent to "extremely annoyed" and 0 was equivalent to "not at all annoyed", 5.0% and 9.1% of respondents rated traffic noise as 8 and above and 7 and above, respectively. The national margin of error for these findings is plus or minus 1.9 percentage points, 19 times out of 20. The results are consistent with an approximate value of 7% for the percentage of Canadians, in the age group studied, highly annoyed by road traffic noise (i.e. about 1.8 million people). We found that age, education level and community size had a statistically significant association with noise annoyance ratings in general and annoyance specifically attributed to traffic noise. The use of the International Organization for Standardization/Technical Specification (ISO/TS)-15666 questions for assessing noise annoyance makes it possible to compare our results to other national surveys that have used the same questions.

Strength of noise effects on memory as a function of noise source and age.

Abstract: The objectives in this paper were to analyse noise effects on episodic and semantic memory performance in different age groups, and to see whether age interacted with noise in their effects on memo ...

The Nord-Trøndelag Norway Audiometric Survey 1996-98: unscreened thresholds and prevalence of hearing impairment for adults > 20 years.

Abstract: As supplement to a general health screening examination (HUNT-II), we conducted a puretone audiometry study in 1996-98 on adults (>20 years) in 17 of 23 municipalities in Nord-Trondelag, Norway, including questionnaires on occupational and leisure noise exposure, medical history, and symptoms of hearing impairment. The study aims to contribute to updated normative hearing thresholds for age and gender, while evaluating the effects of noise exposure, medical history, and familial or genetic influences on hearing. This paper presents the unscreened hearing threshold data and prevalence of hearing impairment for different age groups and by gender. Valid audiometric data were collected from 62% (n=50,723) of 82,141 unscreened invited subjects (age-range 20-101 years, mean=50.2 years, SD=17.0 years). Two ambulant audiometric teams each conducted 5 parallel self-administered, pure-tone hearing threshold examinations with the standard test frequencies 0.25-0.5-1-2-3-4-6-8 kHz (manual procedure when needed). Tracking audiometers were used in dismountable booths with in-booth noise levels well within ISO criteria, except being at the criterion around 200 Hz. The data were electronically transferred to a personal computer. Test-retest correlations for 99 randomly drawn subjects examined twice were high. The mean thresholds recorded were some dB elevated from "audiometric zero" even for age group 20-24 years. As also found in other studies, this might indicate too restrictive audiometric reference thresholds. Males had slightly better hearing or = 30 years from > or =2 kHz, with maximal gender differences of approximately 20 dB at 3-4 kHz for subjects aged 55-74 years. Weighted prevalence data averaged over 0.5-1-2-4 kHz showed hearing impairment >25 dB hearing threshold level of 18.8% (better ear) and 27.2% (worse ear) for the total population--for males 22.2% and 32.0%, for females 15.9% and 23.0%, respectively. Mean hearing loss > or =10 dB at 6 kHz registered for both genders even in age groups 20-24 years may be partly due to calibration artefacts, but might possibly also reflect noise-related socio-acusis.

Noise exposure and subjective hearing symptoms among school children in Sweden.

Abstract: Objective: The aim of the present study was to evaluate factors of importance for the experience of temporary threshold shift (TTS), noise- induced tinnitus (NIT), spontaneous tinnitus (ST) in school children. Subjects and Methods: A total of 671 students aged 13-16 years old were asked to fill in a questionnaire containing items concerning TTS, NIT, ST, hearing loss (HL), heredity for HL, noise exposure, history of otitis media, symptoms of anxiety and depression, psychosocial factors and habits, life satisfaction, chronic medical conditions, age, gender and height. The questionnaire was filled in during school hours. Results: Correlations were found with exercise and eating habits, sleep disturbances, BMI, depressive and anxiety disorders, heredity for HL and noise exposure dosage. The risk for TTS was nine times higher in students who reported having a verified hearing loss than in subjects without subjective or verified complaints of hearing loss. The risk for NIT was approximately four times higher in the group who visited concerts 6-12 times per year as compared to those who never attended concerts. There was almost a threefold increase in the risk for ST in the group that sometimes experienced TTS, as compared to those without TTS, and a tenfold increase in risk for ST in those who reported having a verified hearing loss. Conclusion: In school children, exposure to leisure noise is correlated with tinnitus and the risk increases with increasing noise exposure. Sensitivity to subjective hearing loss has similar risk factors as seen for metabolic syndrome and we suggest that this sensitivity may be another side of metabolic syndrome.

Effect of exposure to a mixture of solvents and noise on hearing and balance in aircraft maintenance workers.

Abstract: Aircraft maintenance workers are exposed to a mixture of solvents in the presence of intermittent noise. For this study these workers exposed to solvent mix and noise, were compared with mill workers exposed to noise alone, printed circuit board operatives exposed to solvents alone and those exposed to none who acted as controls. Tympanometry, acoustic reflex thresholds, transient and distortion product otoacoustic emissions, auditory brainstem potentials, nystagmography and posturography were examined. There was a significant effect on pure tone thresholds for both noise and solvents+noise. The distortion product otoacoustic emissions declined with frequency and exhibited lower DP amplitude with noise compared to solvents and noise group. The transient emissions showed a similar effect. Over 32% of subjects with solvent and noise exposure had abnormalities of the auditory brainstem responses in terms of interwave interval prolongation. The mean acoustic reflex thresholds showed a pattern of differences which differentiate noise from solvent and noise groups. The contralateral pathway appears to be differentially affected by solvent exposure. 32% of subjects in the solvents and noise group had an abnormal posturographic finding. In the solvents and noise group 74% had abnormalities of saccades, 56% of pursuit and 45% of optokinetic nystagmus.

Confounding or aggravating factors in noise-induced health effects: air pollutants and other stressors.

Abstract: Different scientific groups have studied and continue to study the health impacts of physical and chemical agents in the environment. In most cases, every study group has considered the health effect as being solely due to the air pollutant(s) under investigation, for example air pollution without due regard for the simultaneous presence of noise pollution whereas both have an impact on the cardiovascular system. Or in the case of noise studies the contribution of solvent, asphyxiant or metal exposures has not been considered, which can have an impact on hearing impairment. One can, therefore, question the stringency of the available evidence of epidemiological studies in both fields to warrant the consideration of air pollutants as confounding or aggravating factors in studies of specific effects due to noise (and vice versa). In this paper we weigh the existing evidence on the association of noise and air pollutant exposure and associated health impacts. In forthcoming publications, the authors will consider the influence of other factors, which can confound noise studies but are currently not included in the analysis.

Combined effects of noise and styrene on hearing: comparison between active and sedentary rats.

Abstract: In this study, two investigations were carried out with adult Long-Evans rats exposed to increasing concentrations of styrene. In the first experiment, the hearing of rats, which were forced to walk in a special wheel during the exposure, was compared to that of rats which were sleepy in their cage. The active rats were exposed to styrene concentrations ranging from 300 to 600 ppm, whereas the sedentary rats were exposed from 500 to 1000 ppm for 4 weeks, 5 days per week, 6 hours per day. In the second experiment, designed to evaluate the hearing risks at threshold limit values, active rats were exposed either to a noise having a Leq8h of 85 dB (equivalent level of a continuous noise for a typical 8-h workday), or to 400-ppm styrene or to a simultaneous exposure to noise and styrene. In both experiments, auditory function was tested by auditory-evoked potentials from the inferior colliculus and completed by morphological analyses of the organ of Corti. The results of the first experiment showed that the same amount of styrene-induced hearing loss can be obtained by using concentrations approximately 200 ppm lower in active rats than in sedentary rats. The second investigation showed that, in spite of the low-intensity noise and the low-concentration of styrene, there is a clear risk of potentiation of styrene-induced hearing loss by noise. These findings and exposure conditions were discussed and extrapolated with regard to the risk assessment for human beings. The authors propose to decrease the French threshold limit value of styrene for ensuring a high level of protection for human hearing.

Audiometric findings in petrochemical workers exposed to noise and chemical agents

Abstract: This study investigated the occurrence of hearing loss among workers of a petrochemical industry during a period of five years. The records of environmental noise and solvents measurements and the results of annual audiometry performed by the company were examined. The audiometric results of workers from olefin operational areas 1 and 2 and aromatic plant areas exposed to solvents and noise and utility area workers exposed only to noise were analyzed for the standard threshold shift (STS). Despite the low exposures to solvents and a moderate exposure to noise, 45.3% of workers had hearing losses and 29.6% had STS.

Health problems in musicians: A review

Abstract: Among artists, musicians suffer from special health problems related to their occupation and lifestyle. These mainly include musculoskeletal disorders, skin disorders, respiratory disorders, and noise induced hearing impairment. In this review we point out the most prevalent health problems that musicians face in their professional lives as well as the means to prevent them. The characteristics of individual performer and the type of instrument that he/she plays will determine the occupational disorder or disease that a musician may suffer from. The main worry about health problems in musicians is that they can become potentially career-ending disabilities. Therefore well-planned preventive strategies should be employed to help musicians in obtaining long and healthy career.

Could we all be a little more quiet, please? A behavioural-science commentary on 'Research fo a quieter Europe in 2020'

Abstract: European noise research and policy-making overall not so effective thus far is considered from a behavioural science perspective First, an overview is given of a recent strategy paper by the EU's CALM network1, focused on perception-related and emission-related research After a summary of noise effects on human well-being, environmental noise problems are discussed as socio-technical problems where the social part is just as important as the technical part The behavioural and social components of noise emission, transmission, exposure and effect are explicated Environmental stress is considered as a double-sided phenomenon involving subjects' threat appraisal and their coping appraisal, each comprising specific underlying variables From the wider perspective explained, several comments are given on the research strategy CALM is proposing It is argued that: increasing motorisation undermines noise abatement; dose-response relationships reflect only part of the problem; more attention is needed for the causative behaviour of noisy actors; technical noise-reduction measures are necessary but insufficient; and that noise as a daily stressor should be treated in the context of people's overall quality of life Specific suggestions are listed for EU noise research and policy-making One conclusion is that more effective and visionary European noise policies may well be started tomorrow and need not depend on 15 years more research as envisaged in the CALM strategy paper

A comparison of the protective effects of systemic administration of a pro-glutathione drug and a Src-PTK inhibitor against noise-induced hearing loss

Abstract: Both the antioxidant, n-l-acetyl cysteine (L-NAC) and the Src inhibitor, KX1-004, have been used to protect the cochlea from hazardous noise. To date, KX1-004 has only been used locally on the round window. In the current study, the two drugs were administered systemically. LNAC was delivered intraperitoneally at a dose of 325 mg/kg while KX1-004 was administered subcutaneously at a dose of 50 mg/kg. The noise exposure consisted of a 4 kHz octave band of noise at 100 dB SPL for 6 hours/day for 4 days. The drugs were administered once each day, 30 minutes prior to the onset of the noise exposure. The animals' hearing was estimated using the evoked response records from surgically-implanted chronic electrodes in the inferior colliculi. Animals treated with LNAC and KX1-004 had from10 to 20 dB less temporary threshold shift at day 1 and an average 10 dB less permanent threshold shift by day 21 when compared to control saline treated animals. There were no significant side effects (i.e.: appetite loss, weight loss, lethargy, etc.) related to either of the drug treatments. KX1-004 produced at least as much protection as L-NAC, but at a significantly lower concentration.

Protection efficiency of hearing protectors against military noise from handheld weapons and vehicles.

Abstract: Noise attenuation against military noises has been measured in several cases under practical field conditions. Commercial and military versions of earmuff noise attenuation were measured against rifle noise. All the tested earmuffs attenuated the C-weighted peak level to less than 135 dB, which is less than the proposed recommendation value. Combat and shooting exercises create a risk of hearing damage, reaching a peak level of 180 dB. Measurements were done during attack exercises with blank and normal cartridges and during a defence exercise with normal cartridges. The noise exposure levels were relatively moderate (outside the ear 95-97 dB, in ear canal 82-85 dB) for military exercises. Peak levels of 110-120 dB for military trainers were measured in the ear canal during the conscript use of small-bore weapons. Combat vehicles and tanks are noisy, and for noise control during their use headgear with communication properties is worn. Noise inside such headgear was found to reach up to 120 dB, and the noise doses varied between 90 and 105 dB. Noise was also measured for aviation pilots in Finnish jet fighters. The cockpit values averaged 96 dB - 100 dB over the flight, whereas noise in the ear canal averaged 88 dB - 95 dB. The analyses indicated that radio noise is 4-10 dB higher inside the helmet than the background noise is, when measured as equivalent noise. The technicians on the ground were exposed to noise levels varying from 93 to 97 dB over the day. In practice, hearing protectors attenuate noise by 10-30 dB, depending on the frequency content of the noise sources. However, the difference when measured outside and inside hearing protectors varies by 5-10 dB because communication increases the noise level at the entrance of ear the canal. Currently the best protection for soldiers seems to be active noise cancellation ear muffs that are equipped for communication purposes and worn during the entire military exercise.

Therapeutic efficacy of magnesium after acoustic trauma caused by gunshot noise in guinea pigs

Abstract: Conclusions. The present findings show that magnesium administration can significantly reduce threshold shift 7 days after gunshot noise exposure. However, this improvement seems to be temporary, suggesting a probable advantage in prolonging the treatment. Objective. To evaluate the therapeutic efficacy of magnesium administration after hearing loss induced by gunshot noise. Material and methods. Forty-eight guinea pigs were exposed to an impulse noise (blank shot from a rifle; 170 or 176 dB SPL peak). The therapeutic efficacy of magnesium was evaluated by administering either the treatment or a placebo to the traumatized animals for 7 days, beginning 1 h after the trauma. Auditory function was explored for up to 14 days of recovery by recording the compound action potential in the round window. The functional study of hearing was supplemented by histological analysis. Results. The threshold shifts of the 170-dB SPL group that received magnesium were significantly lower than those of controls after 2 and ...

The influence of aging on the noise attenuation of ear-muffs.

Abstract: Ear-muffs are commonly used as personal protectors against the effect of noise. The methods of calculation the A-weighted sound pressure level under the cups of ear-muffs are based on the results of laboratory measurements of noise attenuation, which are carried out in the certification process of the product on brand new samples. Hearing protectors are usually stored for certain periods of time. Next, workers use them in different ambient outdoor conditions as long as there are no signs of their physical damage. The question is. What is the influence of ambient outdoor conditions, usage and storage time of ear-muffs on their attenuation? To answer this question, a three-year study has been undertaken. Four types of ear-muffs, most popular in the Polish work environment, made in Europe, meeting the certification requirements and granted a certification mark, were used in this study. Sixty samples of ear-muffs were worn by workers at noisy workplaces, 40 samples were stored and another 40 were exposed to ambient outdoor conditions. The workers were asked to evaluate subjectively the noise attenuation of the ear-muffs. After one, two and three years time of usage and storage, the sound attenuation of ear-muffs was measured. After the two years the headband force and the cushion pressure of tested samples were measured. The results of sound attenuation measurements were used to calculate the attenuation against high- (H), medium- (M) and low- (L) frequency noise and single number rating (SNR) of the tested earmuffs. The results of the study showed that the attenuation of ear-muffs can be significantly reduced as a function of usage, storage, and exposure to ambient outdoor conditions. The observed decrease of the ear-muffs attenuation corresponded to decrease of the cushion contact area but did not correspond to the subjective workers' assessment.

Complaint data as an index of annoyance--theoretical and methodological issues.

Abstract: Complaining constitutes one facet of all reactions to noise annoyance and is one way to cope with annoyance due to aircraft noise. In order to value and to establish the usefulness of complaint data as an index of annoyance, four questions need to be answered: Which factors lead annoyed residents to complain about aircraft noise or related issues? Which factors keep annoyed residents from complaining? Are the existing ways to handle annoyance adequate and efficient (e.g. keeping track of complaints, reaction to complains, kinds of complaint services)? Which are new ways to handle annoyance adequately and efficiently? In this paper a first attempt to answer these questions is made. Obviously, complaint data do not reflect noise annoyance in the surroundings of airports to the full extent as there are residents living in affected areas who do not complain, as well as residents living in areas with relatively low noise levels who complain. Also there is a large group of people who declare to be highly annoyed and yet, they do not lodge any complaint. Possible intervening factors are gathered that determine if an annoyed resident takes action and complains. It was found that noise levels per se are not the crucial factor for residents' decisions to complain or not to complain. Personal as well as feasibility factors play a vital role. Yet, the ongoing controversy on the relation between annoyance and complaint behaviour seems not resolved yet. However, complaint behaviour seems to be influenced by various aspects and complaint data consequently cannot be accepted as an accurate measure of public annoyance. Further research is required to address the preferred method of handling reaction to noise and the extent to which complaint itself helps with coping, for different groups of residents.

Sleep quality in noise exposed Brazilian workers

Abstract: This study investigated the effect of chronic workplace exposure to excessive noise on sleep quality. It involved 40 male workers aged 33 to 50 years, 20 of whom had been exposed to environmental workplace noise levels of 85 dB or more on 40-hour-a-week jobs. Another 20 workers who were not exposed to excessive noise were used as controls. All subjects were interviewed and submitted to physical examination, pure tone and speech audiometry, immittance testing and nocturnal polysomnography. Comparative analysis demonstrated that the two groups were similar, except for the exposure to noise. Fisher's test comparison of pure tone and speech audiometry and immittance testing revealed mild to moderate noise-induced hearing loss ( P <0.001) in the ≥ 85-dB group. Indicators of sleep continuity were abnormal in both groups, demonstrating poor sleep quality; however, sleep quantity was normal. Of the 40 individuals, 13 (32.5%) presented respiratory sleep disorders. Of those 13, 10 presented daytime somnolence according to the Epworth Scale. The Mann-Whitney test showed that sleep was identical in the two groups. Fisher's exact test revealed no association between altered sleep and hearing status in either group. Our results show that active men working 40-hour-a-week in the presence of excessive noise without adequate protection for more than eight years presented with noise-induced hearing loss but their quality or quantity of night sleep was unaffected. Sensori-neural deafness may represent an element of adaptation against noise during sleep.

The use of hearing protectors among forest, shipyard and paper mill workers in Finland--a longitudinal study.

Abstract: From 1953 to 1995 the usage rate of hearing protective devices (HPD) was tracked at a paper mill, a shipyard, and in selected areas of forestry work. For each work period, observations were made of HPD use among workers. In the paper mill, the usage rate increased steadily from 1965. In 1990, 39% of workers used HPDs full-time. At the shipyard, the usage rate remained low up to the mid-1980s, but thereafter the proportion of full-time users rose to 70%. A similar trend was noted in forest workers, with the full-time use at 97% by the 1990s. Due to the increased usage rate in all measured industries, the mean effective noise level at the ear has decreased to below 85 dB.

Risk by use of hearing protectors--expert programme supports SMEs in appropriate selection and use.

Abstract: Comprehensive protection by use of PPE against the hazards at work requires more than proper selection based on the protection level needed: The PPE user directive (Council Directive 89/656/EEC, Official Journal of the European Communities L 393, 30/12/1989 p.0018 - 0028) requires an assessment of personal protective equipment itself, which has to consider the risks which may be introduced by use of PPE or use of combinations of PPE. As an example risks which may be introduced by use of hearing protectors are described. Assistance in the assessment required by PPE user directive (Council Directive 89/656/EEC, Official Journal of the European Communities L 393, 30/12/1989 p. 0018 - 0028) and in selection and use of hearing protectors with regard to this assessment is presented.

Sound source identification with ANR earmuffs

Abstract: The effect of hearing protective earmuffs which incorporate active noise reduction (ANR) on sound source identification was studied. The purpose was determine whether ANR interfered with the encoding of cues normally used for directional hearing. Right/left, front/back and within quadrant confusions were assessed in quiet using a circular array of eight loudspeakers. Three stimuli, one-third octave bands centered at 0.5 kHz and 4 kHz and broadband noise, were presented. These enabled an assessment of the utilization of mainly interaural time-of-arrival and level differences, and binaural and spectral cues in combination, respectively. Two groups of normal hearing subjects aged 18-30 and 40-55 years, half male and half female, participated. Overall, age, gender, and ANR were not significant determinants of outcome. The probably of correctly discriminating among the eight speakers decreased significantly with the muffs worn, relative to unoccluded listening by 10%, 35% and 40% for the 0.5 kHz, 4 kHz and broadband stimuli, respectively. The pattern of errors indicated that the earmuffs interfered with the encoding of both binaural (interaural level differences) and spectral cues. With ANR small additional right/left confusions were observed for the low-frequency stimulus (time-of ­arrival cue) for speakers close to the midline axis. The results provide further evidence that earmuffs should not be used in situations where the perception of the direction of hazard is a concern. ANR technology does not appear to increase the handicap.

The benefit method: fitting hearing aids in noise.

Abstract: The most common complaint among individuals with hearing impairment is the inability to follow a conversation when several people are talking simultaneously, a noisy listening situation which is completely different from the quiet surrounding of the conventional pure tone audiometry used as basis for the hearing aid settings. The purpose of this report was to present important characteristics of the BeneFit Method (BFM), a procedure that fits the hearing aid under simulated conditions of competing speech and also a clinical pilot evaluation study comparing the BFM to the NAL-R recommendations and also to the Logic procedure, a GN resound proprietary fitting algorithm representing a modern digital hearing aid fitting procedure. Speech recognition scores in noise (SRSN) using monosyllabic words presented under different background noise levels were evaluated on 21 randomly selected subjects with hearing impairment. The subjects were fitted with the same type of hearing aid Danalogic 163D according to the BFM procedure as well as the logic procedure, the latter developed and recommended by the manufacturer. A comparison of the SRSN when using the subjects' current hearing aid fitted according to the NAL-R procedure was also made. Only the BFM procedure provided a significant SRSN improvement compared to the unaided condition (P<0.01) in a signal/speech-noise level of 75/65 dB corresponding to a normal cocktail party condition. Moreover, patients performed significantly higher SRSN when fitted according to the BFM, than when fitted according the Logic or NAL-R procedures. The BFM procedure, which is based on individual and functional detection of hearing thresholds in noise levels corresponding to a cocktail party condition, can improve SRSN significantly. Hearing aids should be fitted under conditions similar to those when the hearing disability is perceived the most, i.e., in an environment with background noise.

Combined effects of noise and gentamicin on hearing in the guinea pig.

Abstract: The last ten years, the use of gentamicin has increased due to antibiotic resistance among bacterial pathogens. One of the side effects of gentamicin is its toxicity on hearing. Several authors had even pointed out synergistic effects of gentamicin and noise on hearing. It was therefore reasonable to think that the damaging effects of noise could be emphasized by a gentamicin treatment of the subjects. In order to test the applicability of the Leq8h for estimating the hazard of noise on animals treated with a non-ototoxic dose of gentamicin (40 mg/kg for 8 days), two experiments were carried out with guinea pigs. The animals were exposed to octave band noises centred at 8 kHz and treated with gentamicin either simultaneously or sequentially with regard to the noise exposure. Two noise exposures having different acoustic energy, respectively Leq8h = 85 dB and 98.8 dB SPL, were tested. The auditory function of the guinea pigs was tested by recording auditory-evoked potentials. The electrophysiological findings were completed by histological data. The gentamicin treatment tested in the current studies did not cause any auditory permanent threshold shift neither cochlear disruptions, although the treatment could be considered as approximately ten times the therapeutic dose used in human. The auditory deficit induced by the mixed exposures to noise and gentamicin did not worsen the noise effect alone in our experimental conditions. As a result, the European value recommended for noise exposure (Leq8h=85 dB) seems to be robust enough to protect gentamicin-treated workers.

Hearing protector performance and standard deviation

Abstract: The attenuation performance of a hearing protector is used to estimate the protected exposure level of the user. The aim is to reduce the exposed level to an acceptable value. Users should expect the attenuation to fall within a reasonable range of values around a norm. However, an analysis of extensive test data indicates that there is a negative relationship between attenuation performance and the standard deviation. This result is deduced using a variation in the method of calculating a single number rating of attenuation that is more amenable to drawing statistical inferences. As performance is typically specified as a function of the mean attenuation minus one or two standard deviations from the mean to ensure that greater than 50% of the wearer population are well protected, the implication of increasing standard deviation with decreasing attenuation found in this study means that a significant number of users are, in fact, experiencing over-protection. These users may be disinclined to use their hearing protectors because of an increased feeling of acoustic isolation. This problem is exacerbated in areas with lower noise levels.

Noise-induced hearing loss in young people

Abstract: To the Editor— The excellent article by Chung et al1 concluded that 61% of the young people who responded to their Web-based survey experienced tinnitus or hearing loss as a result of attending loud music concerts Also, 43% of the respondents experienced these auditory symptoms after exposure to loud music in clubs However, only 14% of the respondents ever wore ear plugs at a venue in which loud music was played Fortunately, a majority of the respondents (66%) could be motivated to try hearing …

Hearing in military pilots: One-time audiometry in pilots of fighters, transports and helicopters

Abstract: INTRODUCTION: Pilots are exposed to potentially harmful levels of noise, the actual consequences of which are still poorly documented. We have determined the audiometric profiles of pilots as a function of age and type of aircraft (i.e., fighter, transport, helicopter) and have searched for risk factors of deafness other than noise in a pilot population. METHODS: We examined 521 French military pilots ages 20-40 yr during their annual medical check-ups. Pilots were interviewed using a standardized questionnaire and data from tonal audiograms of both ears were collected. Hearing levels were compared between groups of age and aircraft category. RESULTS: Abnormal hearing levels in pilots were found essentially at high frequencies with a marked notch on audiograms at 6 kHz. Left ears had a significantly poorer performance compared with right ears. At a given age, transport pilots had, on average, better hearing at 8 kHz than other pilots, despite a higher number of flying hours. In addition to the 6 kHz notch, helicopter pilots showed a significant hearing loss at 3 kHz. Such an enlargement of the impaired frequency range can disturb speech communication. Prevalence of otitis media in childhood was significantly higher in pilots with abnormal hearing. DISCUSSION: Pilots flying fighter and helicopter aircraft are at a higher risk of hearing loss compared with pilots flying transport aircraft. Improvements in ear protection seem particularly needed for the left ear. Hearing losses can potentially compromise speech communication in helicopter pilots. Language: en

Noise-induced hearing loss is exacerbated by long-term smoking

Abstract: Objective: To analyse the influence of long-term smoking on the hearing threshold of individuals subjected to occupational noise exposure. Design: Prospective observational cohort study. Setting: Occupational health examination of noise-exposed employees in the brick manufacturing industry. Participants: A study group of long-term smokers (n = 30) and a control group of non-smokers (n = 58) were identified from a population of 227 male noise-exposed employees. Individuals of both groups were employed for 10 years or more at a single brick manufacturing plant. Data on noise exposure, smoking habits, medical and otological history were collected and standard pure tone audiometry was obtained. Exclusion criteria included asymmetrical or conductive hearing loss, uncontrolled systemic illnesses, history of head injury, chronic middle ear pathology or major ear operations. Main outcome measure: Pure tone audiometry. Results: Both groups had similar mean age and total duration of occupational noise exposure. The median age-corrected hearing thresholds at 3 and 4 kHz in the smokers group were significantly higher (∼7dB) than those in the non-smokers group. No statistical difference in the hearing thresholds between both groups was found in any other tested frequency (0.5, 1, 2, 6 and 8 kHz). Conclusion: Long-term smokers with occupational noise exposure may, on the basis of this limited study, have a higher risk of developing permanent hearing loss at 3 and 4 kHz when compared with non-smokers with a similar occupational history.

European standardisation of hearing protectors

Abstract: European legislation based on the New Approach requires that technical requirements for products are given in harmonised European standards. The Directive 89/686/EEC on Personal Protective Equipment came into force in 1995. The existence of product and testing standards is a prerequisite for the effective implementation of the directive. There was a need to develop several standards in a very short time period and the basic standards for hearing protectors have already been revised once. It is important to continue the validation of the standardized testing methods and requirement levels. This requires good co-operation and research between test laboratories and research institutes, especially as it is necessary to ensure new products comply with these technical requirements.

Effects of coldness on the protective performance of earmuffs.

Abstract: The type test of hearing protectors (HPD) for certification purposes will be conducted in laboratory at room temperature. Optionally, the mechanical durability of HPDs will be tested in cold environment by a drop test. The purpose of this study was to find out the relevance of the drop test, the change of performance in HPD protection, and finally to estimate the possible change of protection efficiency against noise in cold environment. In total, 22 HPDs were selected to the measurements: 18 earmuffs, and 4 earmuffs attached to an industrial helmet. Attenuation of each earmuff cup was measured by applying insertion loss method for the test subjects in cold. The change of attenuation and temperature of cushion ring was followed up to nine minutes using 30-second intervals for sampling. Three HPDs were damaged in the test. The replaceable cushion was broken in two earmuffs and in one helmet-mounted HPD. The replaceable parts were replaced, and the HPD with attachment failure was removed from insertion loss measurement. In nine HPDs the relative change was less than 3 dB, and was at worst 10 dB. This change was typically at low frequencies, 125 Hz at the beginning when cooled HPDs were placed. In various HPDs the time to get the attenuation levelled varied from 1.5 minutes to 8 minutes. The recovery was dependent on the temperature of the cushion ring. In all cases the temperature of the full attenuation was achieved when the cushion ring reached 7oC. This temporary decrease in attenuation will have a minor effect to the protection efficiency, when the HPD is used full time during the whole exposure duration. A typical group of forest workers will have their exposure interrupted. The chain saws have to refuel, and the chain needs to be sharpened about every 40 minutes. During 6 hour daily operational time there will be about 9 - 10 minute break, long enough to cool the cushion ring back to below zero at -10oC, if the helmet mounted earmuffs are placed in stand-by position. In the worst case this will cause 1.6 dB increase in daily exposure level to noise.

The role of oxidative stress in noise-induced hearing loss

Abstract: Modern research has provided new insights into the biological mechanisms of noise-induced hearing loss, and with these new insights comes hope for possible prevention or treatment. Underlying the classic set of cochlear pathologies that occur as a result of noise exposure are increased levels of reactive oxygen species (ROS) that play a significant role in noise-induced hair cell death. Both necrotic and apoptotic cell death have been identified in the cochlea. Included in the current review is a brief review of ROS, along with a description of sources of cochlear ROS generation and how ROS can damage cochlear tissue. The pathways of necrotic and apoptotic cell death are also reviewed. Interventions are discussed that target the prevention of noise-induced hair cell death: the use of antioxidants to scavenge and eliminate the damaging ROS, pharmacological interventions to limit the damage resulting from ROS, and new techniques aimed at interrupting the apoptotic biochemical cascade that results in the death of irreplaceable hair cells.