High-frequency (10-18 kHz) hearing thresholds: reliability, and effects of age and occupational noise exposure.

The objective was to investigate the reliability and effects of age and noise on high-frequency hearing thresholds. A cross-sectional study was used involving 187 exposed and 52 non-industrial noise-exposed subjects selected randomly from noise-exposed and non-industrial noise-exposed subjects, respectively. Each subject was tested with both conventional-frequency (0.25-8 kHz) and high-frequency (10-18 kHz) audiometry. Test-retest results showed that high-frequency audiometry (HFA) was as reliable as the conventional procedure. Although the inter-subject variation was large, the intra-subject variation was small, indicating that HFA can be used more reliably than the conventional procedure to monitor individual cases over time. Both the hearing threshold at high frequencies and the upper frequency limit deteriorated as a function of age and frequency. The exposed subjects had significantly higher hearing thresholds than the non-exposed subjects at all the high frequencies tested, the difference between the two groups being greatest at 14 kHz. Multivariate analysis indicated that age was the primary predictor and noise exposure the secondary predictor of hearing thresholds in a high frequency range (10-18 kHz). In contrast, multivariate analysis indicated the reverse order-noise exposure as the primary predictor, then age-for a conventional frequency range (0.25-8 kHz). The results of this study suggest that HFA might be used as an early indicator for noise-induced hearing loss and acoustic trauma rather than audiometry at a conventional frequency (4 kHz), particularly for younger groups.     

Noise-induced hearing loss and hearing conservation in mining

BACKGROUND: Noise exposure is prevalent in mining, and as the prevalence of noise-induced hearing loss has not changed much in the past two decades, hearing conservation is an important issue. OBJECTIVES: To review the literature and highlight important developments in the field. METHODS: A review of the literature using OVID as the primary search engine, using the search terms as: noise, occupational; hearing loss, noise induced; ear protective devices; and mining. RESULTS: A total of 66 articles were found, but only 11 were in the English language and few were published in the past 10 years. This is disappointing, because neither noise exposure nor the consequent risk of noise-induced hearing loss seems to have changed much in the past 20 years. Noise is, however, a generic hazard, and this article reviews current best practice in prevention.     

Occupational noise-induced hearing loss

Occupational noise-induced hearing loss is, at least in theory,preventable. One way to assess the problem and whether preventativemeasures are effective is to assess employees' hearing. In orderto minimize cost and time off work this can be carried out effectivelyin the workplace as long as certain conditions are met.     

Surveillance for work-related hearing loss in the UK: OSSA and OPRA 1997-2000

Surveillance data on occupational audiological disorders have been collected by the Occupational Surveillance Scheme for Audiological Physicians (OSSA) since October 1997 and by the Occupational Physicians Reporting Activity (OPRA) from January 1996. During the 3 years ending in September 2000, a total of 1620 new cases were received from consultant audiological physicians; 988 new cases were estimated from reports by occupational physicians in the period from October 1997 to September 2000. The annual incidence of occupational noise-induced hearing loss (NIHL) was 1.94 and 1.23 per 100 000 workers for the OSSA and OPRA schemes, respectively. The median age at diagnosis with NIHL was 59 years in OSSA reports and 50 years in OPRA; nearly all cases were seen in men (95.6 and 92.5% male cases for OSSA and OPRA, respectively). High incidence rates based on OSSA reports were seen in foundry labourers (64.0 per 100 000 employed), coal gas and coke oven furnace workers (54.6), workers in transport and communication (43.1), metal workers (31.3), and members of the armed forces (28.3). Data from occupational physicians point to high rates in sawyers and woodworking machinists, metal furnace workers, coach and carriage builders, maintenance fitters, and engineering labourers. Among workers aged < or =45 years, those in manufacturing and the armed forces were prominent. The long latency of occupational hearing loss makes surveillance difficult, but consistent patterns in occupational risk suggest targets for preventive efforts.     

Dog noise as a risk factor for hearing loss among police dog handlers

AIM: To determine the sources of noise exposure among police dog handlers and to examine whether these levels might lead to noise-induced hearing loss. METHODS: We conducted a cross-sectional study at four Royal Air Force bases using a noise survey, a postal questionnaire and medical record review. The noise survey was conducted following task analysis. We surveyed police dog handlers and a comparison group of police who had never been dog handlers, using a postal questionnaire on noise exposures and confounders. Audiometric and otological data were extracted from medical records. RESULTS: The noise survey revealed significant exposures due to dogs, travelling in vans and aircraft noise during foot patrol. The overall response rate to the questionnaire was 56% (29 police dog handlers, 24 police officers). Five subjects (9.4%) had age-corrected hearing loss exceeding 10 dB, averaged over the 4 and 6 kHz frequencies, affecting the left ear only, but there were no differences between dog handlers and controls. CONCLUSION: Although the measured noise exposures of police dog handlers did not exceed current legal limits, the noise levels at times are such that the proposed Physical Agents (Noise) Directive has implications for employers who use dogs for security purposes.     

Audiometric notch as a sign of noise induced hearing loss

OBJECTIVES—To investigate the relation between different types of exposure to noise and a classic sign of noise induced hearing loss (NIHL), the audiometric notch.METHODS—The study sample had exposure to both continuous and impulse noise and was drawn from a population of electrical transmission workers. Audiograms, taken as part of a hearing conservation programme, were read by three clinicians experienced in the assessment of NIHL. Working independently and using their clinical judgment, they were asked to identify localised increases in the threshold of hearing (audiometric notches) which they would attribute to noise, had a suitable history of exposure been elicited. Prevalent cases of NIHL were identified by the presence of a notch in either ear. Risk factors for NIHL were assessed by a questionnaire which sought information about exposure to air blast circuit breaker noise; firearms; explosions, and continuous noise. The odds of exposure to these factors in those with and without hearing loss were calculated, and odds ratios (ORs) and 95% confidence intervals (95% CIs) were estimated by logistic regression.RESULTS—Of the 648 questionnaires sent out 357 were returned, a response rate of 55%. Of these, at least two out of the three assessors identified 175 (49%) people with a notch at any audiometric frequency. There was no association between these cases and the NIHL risk factors identified by the questionnaire, but a further frequency specific analysis showed a small proportion of people (15 (4%)) with notches at 4 kHz who had the expected associations with exposure to noise and a significant OR for firearms of 4.25 (95% CI 1.28 to 14.1). The much larger proportion of people with 6 kHz notches (110 (31%)) did not show these associations.CONCLUSIONS—To diagnose NIHL it is important to elicit a detailed and accurate history of exposure to noise: although the notch at 4 kHz is a well established clinical sign and may be valuable in confirming the diagnosis, the 6 kHz notch is variable and of limited importance.     

Noise-induced hearing loss,nationality, and blood pressure

Noise exposure has been associated with increased catecholamine production and blood pressure elevation in laboratory studies and in human volunteers. Epidemiologic studies have given conflicting results. In order to determine whether noise-induced hearing loss predicts a rise in blood pressure, we reviewed occupational medicine records in an occupational health center serving three companies where noise exposure is commonly found. Height, weight, blood pressure, and screening audiometry are obtained as par of routine occupational health screening, and the results of the screening visit are abstracted from written clinical records. The results of pure tone screening audiometry are reported in nonstandardized fashion (Normal, WNL, NAD, for example, for normal). We reviewed records from 1990 and 1991 inclusive. One investigator, blind to blood pressure status, assigned each record to “no hearing loss,” “not codable,” or “hearing loss assumed to be due to noise” on the basis of the written audiometry report. Hearing loss due to causes other than noise was considered not codable. No attempt was made to quantify severity of hearing loss. Two hundred and sixteen charts were excluded as “not codable,” 1,535 were classified as having no hearing loss, and 610 had some degree of hearing loss, most probably due to noise exposure. To adjust for confounding covariates, multiple regression analysis was used and indicated that hearing status improves the regression model for predicting diastolic blood pressure (p = 0.04), following age, nationality, body mass index (BMI), and month of testing, although the effect is small. Stratification by age and BMI revealed increased diastolic pressure in the group with hearing loss under age 45, regardless of obesity. Only age and BMI significantly improved the regression model for systolic blood pressure for the group as a whole. However, when large national groupings were evaluated independently, noise-induced hearing loss was associated with higher systolic and diastolic readings among Asians (n = 539) and Sub-Saharan Africans (n = 75), with correlation coefficients ranging from 0.18 to 0.32. Noise-induced hearing loss failed to improve the blood pressure regression model for Europeans/North Americans (n = 150), Arabs (n = 1020), or North Africans (n = 352). In this study, hearing loss attributed to industrial noise exposure appears to be associated with elevated resting blood pressure only within certain ethnic groups.     

Air blast circuit breaker noise and hearing loss: a multifactorial model for risk assessment

The assessment of the risk to hearing from impulse noise exposure may be a problem for the occupational physician because existing legislative and international noise exposure standards deal primarily with continuous noise, and are not valid in excess of the peak exposure limit of 200 pa (140 dB). Noise exposure in excess of this level, for example that due to firearms, is frequently perceived as harmful, but this is not necessarily the case, as impulse noise standards do, in fact, allow exposure with a maximum in the order of 6.3 kPa (170 dB). To illustrate this, a cross-sectional group of electrical transmission workers have been studied who were exposed to significant levels of impulse noise from air blast circuit breakers and firearms. Important hearing loss factors have been identified by means of a specially designed questionnaire. Using the Health & Safety Executive definition, the risk of hearing loss was determined by calculating prevalence odds ratios (ORs) for exposure to these factors. The OR for those with fewer than eight unprotected air blast circuit breaker exposures was 2.27 (95% confidence interval (CI), 1.01-5.08), whilst for those with more than eight exposures the OR was 2.10 (95% CI, 0.97-4.54). For firearm exposure, ORs of 1.61 (95% CI, 0.95-2.74) were noted in the medium exposure group and 2.05 (95% CI, 1.08-3.86) in the high exposure group. When all the factors were included in the model, the most significant factor was age. The study gives support to the impulse noise exposure criteria, confirming the borderline risk from air blast circuit breaker noise exposure and the relative safety of moderate gunfire exposure.     

Noise-induced hearing loss in randomly selected New York dairy farmers

To understand better the effects of noise levels associated with dairy farming, we randomly selected 49 full-time dairy farmers from an established cohort. Medical and occupational histories were taken and standard audiometric testing was done. Forty-six males (94%) and three females (6%) with a mean age of 43.5 (+/- 13) years and an average of 29.4 (+/- 14) years in farming were tested. Pure Tone Average thresholds (PTA4) at 0.5, 1.0, 2.0, and 3.0 kHz plus High Frequency Average thresholds (HFA3) at 3.0, 4.0, and 6.0 kHz were calculated. Subjects with a loss of greater than or equal to 20 db in either ear were considered abnormal. Eighteen subjects (37%) had abnormal PTA4S and 32 (65%) abnormal HFA3S. The left ear was more severely affected in both groups (p less than or equal to .05, t-test). Significant associations were found between hearing loss and years worked (odds ratio 4.1, r = .53) and age (odds ratio 4.1, r = .59). No association could be found between hearing loss and measles; mumps; previous ear infections; or use of power tools, guns, motorcycles, snowmobiles, or stereo headphones. Our data suggest that among farmers, substantial hearing loss occurs especially in the high-frequency ranges. Presbycusis is an important confounding variable.     

Risks of developing noise-induced hearing loss in employees of urban music clubs

Noise-induced hearing loss has previously been reported among rock musicians. This study sought to determine whether a hazard of noise-induced hearing loss exists for music club employees other than musicians themselves. Sound levels at eight live-music clubs were measured and symptoms of noise exposure in 31 music club employees were assessed by questionnaire. The average sound level at the various clubs during performances ranged from 94.9 to 106.7 dBA. The overall sound level average, including both performance and ambient levels, ranged from 91.9 to 99.8 dBA. Symptoms of noise exposure, such as tinnitus and subjective hearing loss, correlated with sound intensity. Only 16% reported regular use of hearing protection. We conclude that employees of music clubs are at substantial risk of developing Noise-Induced Hearing Loss, due to chronic noise exposure which consistently exceeded safe levels. Hearing protection is used much too infrequently. The development of hearing conservation programs for this large group of workers is essential. Am. J. Ind. Med. 31:75–79 © 1997 Wiley-Liss, Inc.     

Occupational noise exposure and hearing loss: A study of knowledge,attitude and practice among Tanzanian iron and steel workers

Abstract

We assessed Knowledge Attitude and Practice (KAP) regarding occupational noise exposure, Noise-induced hearing loss, audiometry and use of hearing protection devices among iron and steel factory workers exposed to high noise level. A modified, validated, structured questionnaire was used to collect information from 253 male workers randomly selected from the four factories. The sum scores for each domain of KAP were computed. Scores above 75% were defined as good knowledge and positive attitude. For practice, scores of >50% were defined as good. Independent samples t-test and Chi-squared test were used to analyze association between KAP and continuous/categorical variables respectively. Majority of workers displayed poor knowledge and poor practice (94%), but 76% displayed a positive attitude. Most of the workers (86%) had never been provided with hearing protection devices. The mean scores for attitude and practice differed significantly between the four factories (one-way ANOVA, p?<?0.001). Implementation of hearing conservation program with provision of hearing protection devices are suggested.     

Cardiovascular conditions,hearing difficulty,and occupational noise exposure within US industries and occupations

Background

The purpose of this study was to estimate the prevalence of occupational noise exposure, hearing difficulty and cardiovascular conditions within US industries and occupations, and to examine any associations of these outcomes with occupational noise exposure.

Methods

National Health Interview Survey data from 2014 were examined. Weighted prevalence and adjusted prevalence ratios of self‐reported hearing difficulty, hypertension, elevated cholesterol, and coronary heart disease or stroke were estimated by level of occupational noise exposure, industry, and occupation.

Results

Twenty‐five percent of current workers had a history of occupational noise exposure (14% exposed in the last year), 12% had hearing difficulty, 24% had hypertension, 28% had elevated cholesterol; 58%, 14%, and 9% of these cases can be attributed to occupational noise exposure, respectively.

Conclusions

Hypertension, elevated cholesterol, and hearing difficulty are more prevalent among noise‐exposed workers. Reducing workplace noise levels is critical. Workplace‐based health and wellness programs should also be considered.

     

Noise and hearing loss: a review

BACKGROUND: Noise-induced hearing loss is a major cause of deafness and hearing impairment in the United States. Though genetics and advanced age are major risk factors, temporary and permanent hearing impairments are becoming more common among young adults and children especially with the increased exposure to portable music players. Though treatment options are limited for most people with noise-related hearing loss, several modifiable health behaviors that should begin in childhood might prevent or delay the onset of hearing impairment. The purpose of this article is to review modifiable and non-modifiable risk factors, comorbidity, and the role of health education in the prevention of noise-induced hearing loss. METHODS: Review of current literature in the etiology, prevention, and treatment of noise-induced hearing loss as well as the role of health education. RESULTS: Non-modifiable risk factors related to noise-related hearing loss include increasing age, genetics, male gender, and race. Modifiable risk factors are voluntary exposure to loud noise, nonuse of hearing protection, smoking, lack of exercise, poor diet, tooth loss, and the presence of diabetes and cardiovascular disease. CONCLUSIONS: As hearing impairment among children and teenagers rises due to mostly voluntary exposure to loud noise, there are many implications for health education. Health educators need to address barriers to the use of hearing protection, deliberate exposure to loud music, and other modifiable risk factors, which cause and exacerbate hearing loss among those exposed to loud noise.     

某纺织厂噪声作业工人听力损失调查

目的:通过对某纺织厂噪声强度监测和对作业人员的听力检测,掌握噪声强度及听力损失的发生情况,为采取积极有效的防护措施提供依据。方法:用HS6288系列噪声分析仪监测作业场所噪声强度,并进行频谱分析,计算累积噪声暴露量(CNE);对某纺织厂接触噪声作业的无耳疾患的931人进行听力检测;用EpiData建立数据库,SAS软件8.0统计包进行统计分析。结果:该厂噪声车间的连续等效A声级均超过了85db(A),主要为中高频噪声;噪声作业人员有高频听力损失264人,检出率为28.36%,语频听力损失9人,检出率为0.97%;高频和语频听力损失的发生率均随累积接触噪声剂量的增加而升高;听力损失发生率及程度与工龄密切相关;织一车间和织二车间噪声平均>100dB(A),高频听损率分别为43.68%和42.62%,在强噪声车间作业戴耳塞者高频听损检出率低于不戴耳塞者,但高频听力损失的检出率仍然明显高于其他车间;听力损失曲线以高频凹陷谷点为3kHz及4 kHz的“V”字型为主,占高频听力损失的73.0%。结论:该厂噪声污染较严重,对作业人员听力已经产生了明显影响,应采取积极的综合预防性措施来控制噪声对作业人员健康的影响。     

电厂噪声作业工人累积接噪量与听力损害关系

目的　了解电厂噪声作业工人的听力损失发生状况以及与噪声累积暴露量的关系。方法　采用横断面研究方法 ,研究对象为参加噪声作业一年以上的无耳疾患史的 35 6名工人 ,调查年龄、性别、噪声作业的工龄、听力损失情况和作业场所噪声强度。结果　作业工人听力损失的发生率为 31.74%(按人数计 )。听力损失发生率在男、女性别上的分布差别无显著意义。听力损失发生率随累积接触量的增加而增加 ,存在典型的剂量 -反应关系 ,呈明显正相关 (r =0 .9916 ,P <0 .0 5 )。结论　累积接噪量能较全面反映噪声作业工人噪声接触水平 ,是评价噪声暴露与听力损害剂量 -反应关系最好的暴露评价指标。     

高温作业与噪声对人耳听力的联合影响

目的为探讨高温与噪声联合作用对作业工人听力的影响。方法联合作用组(A组)67名,单纯噪声组(B组)56名,对照组54名(C组)进行听力损伤的调查。结果噪声强度A组LAeq87．4dB(A),B组LAeq87．0dB(A);各组听损发生率A组＞B组＞C组,组间比较(P＜0．01);各组间不同频率的听阈均值对比中,2、3、4、6kHz以A组＞B组＞C组,各组间比较(P＜0．01)。结论提示高温与噪声对工人高频听阈有协同作用。