Annoyance and health risk caused by military low-altitude flight noise

Summary Effects of noise of low-flying military jet aircraft were investigated from demoscopic and epidemiological points of view. Areas with different low-altitude flight noise exposure were compared with one another as to subjective annoyance, casual blood pressure and ear symptoms. With the same energy equivalent sound pressure level (Leq), the subjective disturbance caused by military low-altitude flight noise was essentially greater than that due to ordinary flight noise (in the neighbourhood of civil airports). A comparison of several areas revealed that frequencies of ear symptoms (tinnitus lasting more than one hour and permanent hearing threshold shifts of > 30 dB) were higher only in areas where maximal flight noise levels considerably exceeded 115 dB (A) accompanied by rapid noise level increases. Blood pressure measurements yielded significantly higher values (group difference 9 mm Hg systolic) in girls living in these highly exposed areas. Acoustic limits are proposed with respect to public health.     

High-frequency audiometry for the early diagnosis of occupational acoustic trauma

We investigated a total of 537 patients (68 men, 469 women) working in the textile industry to ascertain their hearing level in the conventional hearing range as well as in the HF range. The persons tested work at 3 different noise levels (80-84, 85-89 and 90-94 dB [A] Leq). The differences in the hearing thresholds of the three sound level groups mentioned above were checked by means of discrimination analysis. The first hearing level changes noise levels below 90 dB develop mainly in the HF range; in the conventional hearing range, however, the hearing levels remain unchanged even during long exposure times. Hearing level impairment in the conventional range occurs only in the sound level group of 90-94 dB (A) Leq without attaining any social importance. The tests clearly show that if the noise level damage risk criterion of 85 dB (A) Leq at which hearing is impaired, is not exceeded any hearing lesions involving social hearing loss are definitely avoided.     

某市金属制造业工人噪声危害知、信、行与听力水平关联性分析

目的 调查某市金属制造业工人噪声危害知、信、行与纯音听力水平现状,并分析其关联性.方法 选择金属制造业的噪声作业者作为研究对象,问卷法调查其对噪声危害的知、信、行现状,并检测其接触的噪声声级和纯音听力水平.结果 本次共纳入188名研究对象,噪声性听力损失(noise-induced hearing loss,NIHL)...     

噪声作业场所环境危险因素对噪声性听力损失的影响

目的 探讨噪声作业场所除噪声外其他环境危险因素对个体听力损失的影响,从环境因素出发寻找噪声性听力损失(NIHL)的高危易感人群.方法 采用病例对照研究方法,选择南方某市某大型空调生产企业连续性噪声暴露强度在75～120 dB范围内2400名作业工人为研究对象,比较同一噪声暴露组内噪声作业人员的左耳3000 Hz频段听阈位移情况,筛选出听阈位移最大的10%个体作为本研究的易感人群组,共202例;听阈位移最小的10%个体作为耐受人群组,共204例.并对两组人群进行作业场所职业卫生调查和问卷调查,通过单因素和多因素分析环境因素对噪声性听力损失的影响.结果 单因素logistic回归分析发现,噪声作业人员中吸烟、饮酒、工作接触有机溶剂、接触重金属、接触高温、接触粉尘人群是NIHL的高危易感人群.进一步的多因素分析发现,仅工作过程中接触高温是NIHL的高危因素,噪声暴露中同时接触高温的NIHL危险度是单纯噪声暴露的1.804倍(95%CI:1.101～2.958).结论 噪声作业同时有高温暴露的人群是NIHL的高危易感人群.     

High-frequency audiometry: a means for early diagnosis of noise-induced hearing loss

Noise-induced hearing loss (NIHL), an irreversible disorder, is a common problem in industrial settings. Early diagnosis of NIHL can help prevent the progression of hearing loss, especially in speech frequencies. For early diagnosis of NIHL, audiometry is performed routinely in conventional frequencies. We designed this study to compare the effect of noise on high-frequency audiometry (HFA) and conventional audiometry. In a historical cohort study, we compared hearing threshold and prevalence of hearing loss in conventional and high frequencies of audiometry among textile workers divided into two groups: With and without exposure to noise more than 85 dB. The highest hearing threshold was observed at 4000 Hz, 6000 Hz and 16000 Hz in conventional right ear audiometry, conventional left ear audiometry and HFA in each ear, respectively. The hearing threshold was significantly higher at 16000 Hz compared to 4000. Hearing loss was more common in HFA than conventional audiometry. HFA is more sensitive to detect NIHL than conventional audiometry. It can be useful for early diagnosis of hearing sensitivity to noise, and thus preventing hearing loss in lower frequencies especially speech frequencies.     

Program for hearing loss prevention in four metallurgical factories in Piracicaba, São Paulo, Brazil

This study analyzes noise control programs in four metallurgical factories in Piracicaba, S?o Paulo, Brazil. From 1997 to 2001, 741 workers were examined and the programs were analyzed based on workers' profiles (2,270 audiometric exams) and documents on hearing preservation programs. 41% of workers presented hearing loss (mean age 42.3; mean years of work 16.7). 104 workers with more than one audiometric exam presented changes in hearing threshold. 36.5% (38 workers) developed noise-induced hearing loss (NIHL) and 63.5% (66 workers) with existing NIHL showed worsening of their hearing threshold. In these factories, 69.5% of workers were exposed to > or = 84dB(A). We concluded that the hearing preservation programs are not adequately organized and that workers are still exposed to high noise levels at work, posing a risk for NIHL. In addition, the current legislation on hearing loss prevention is not enforced.     

Amplitude changes in otoacoustic emissions after exposure to industrial noise

Noise-induced hearing loss (NIHL) is a frequent problem in industrial settings, especially where a high noise level is present. It is permanent, and irreversible, but preventable. Routine audiometry (an objective and time consuming) test is used for NIHL screening. Otoacoustic emissions (OAEs) are recently proposed as a more sensitive test for early diagnosis of NIHL. In this study, we aimed to compare the results of pure tone audiometry (PTA) with OAE in the diagnosis of NIHL. In a cross-sectional study on 120 workers (in three groups: Not exposed to noise, exposed to noise without NIHL and exposed to noise with NIHL), we compared the results of PTA and OAE. OAE can detect some changes in the function of hearing system in subjects exposed to noise, and these changes are apparently prior to hearing loss, which is diagnosed by PTA. OAE is a more sensitive method for the early diagnosis of cochlear damage than PTA, and can be performed in industrial settings for NIHL screening.     

某市职业人群噪声性听力损失的双向队列研究

目的 了解某市职业人群噪声性听力损失情况及其影响因素,分析不同噪声接触声级的相对危险度、归因危险度。方法 采用整群抽样方法,选择2010年1月1日—2016年12月31日进行职业健康体检的20家企业接触噪声的3 580名作业工人为研究对象。2017年1月1日建立动态研究队列,观察终止时间为2019年12月31日。收集研究对象2017年之前的现场检测和体检数据,并开始观察对象2017年1月1日之后3年的听力损失情况,采用多因素Cox比例风险模型研究工人噪声性听力损失发生的影响因素。结果 3 580名工人中男性2 849人,女性731人;平均年龄（39.42±7.69）岁;平均工龄（11.50±7.06）年。随访时间共计28 585.65人年,发生噪声性听力损失91例,发病密度为0.003 2/人年。随着接触噪声声级的增加,工人噪声性听力损失发病密度、相对危险度（RR）、归因危险度百分比（AR%）也随之增加。Cox比例风险模型的回归分析结果显示：女性发生听力损失的风险是男性的0.148倍;防护用品合适且全程佩戴工人发生听力损失的风险是不合适或不佩戴的0.407倍;年龄每增加1岁,工人发生听...     

Combined exposure to noise and vibration and its effects on workers' hearing

OBJECTIVE: To assess the exposure of bus drivers to noise and whole-body vibration (WBV) and to examine the possibility of an association between these risk factors for noise-induced hearing loss. METHODS: A cross-sectional study was carried out among 141 bus drivers who underwent an audiometry test. This group was classified and internally stratified in subgroups of "exposed" and "controls" according to cumulative working time as bus drivers. Their exposure to noise and vibration was assessed. The association between noise-induced hearing loss (NIHL) and the set of explanatory variables was analyzed through logistic regression. RESULTS: The average (+/- standard deviation) weekly noise exposure of front-engine bus drivers was 83.6 +/- 1.9 dB(A), while rear-engine bus drivers were exposed to 77.0 +/- 1.1 dB(A). The weighted average of vibration acceleration was 0.85/m(2). In the best adjusted model, the multivariable analysis showed that age (>44; OR=2.54; 95% CI=1.15-5.62), diabetes (OR=5.46; 95% CI=0.95-31.4), and the level of noise emission [>86.8 dB(A); OR=2.76; 95% CI=1.24-6.15] were risk factors for NIHL. In another model studied, WBV exposure was significant in determining NIHL. CONCLUSIONS: Bus drivers were exposed to significant WBV levels. The noise exposure was more pronounced in front engine than in rear-engine vehicles. No association between WBV exposure and NIHL was observed and no interaction was found between WBV and noise exposure. Further studies are required as other model indicated an association between WBV and NIHL.     

Prevalence of permanent hearing threshold shift among workers of Indian iron and steel small and medium enterprises: a study

Occupational noise exposure and noise-induced hearing loss (NIHL) have been recognized as a problem among workers in Indian industries. The major industries in India are based on manufacturing. There are appreciable numbers of casting and forging units spread across the country. The objective of this study is to determine the prevalence of permanent hearing threshold shift among the workers engaged in Indian iron and steel small and medium enterprises (SMEs) and compared with control group subjects. As a part of hearing protection intervention, audiometric tests were conducted at low (250-1000 Hz), medium (1500-3000 Hz), and high (4000-8000 Hz) frequencies. The occurrence of hearing loss was determined based on hearing threshold levels with a low fence of 25 dB. Comparisons were made for hearing threshold at different frequencies between the exposed and control groups using Student's t test. ANOVA was used for the comparison of hearing threshold dB at different frequencies among occupation and year of experience. A P value <0.05 was considered as statistically significant. All data were presented as mean value (SD). Over 90% of workers engaged in various processes of casting and forging industry showed hearing loss in the noise-sensitive medium and higher frequencies. Occupation was significantly associated with NIHL, and hearing loss was particularly high among the workers of forging section. The analyses revealed a higher prevalence of significant hearing loss among the forging workers compared to the workers associated with other activities. The study shows alarming signals of NIHL, especially in forging workers. The occupational exposure to noise could be minimized by efficient control measures through engineering controls, administrative controls, and the use of personal protective devices. Applications of engineering and/or administrative controls are frequently not feasible in the developing countries for technical and financial reasons. A complete hearing conservation programme, including training, audiometry, job rotation, and the use of hearing protection devices, is the most feasible method for the protection of industrial workers from prevailing noise in workplace environments in the developing countries.     

Detection and Clinical Diagnosis of Noise-Induced Hearing Loss by Otoacoustic Emissions

The purpose of this study was to explore the application of the click-evoked and distortion products otoacoustic emissions (CEOAEs and DPOAEs, respectively) in the diagnosis and detection of noise-induced hearing loss (NIHL). The study group consisted of 283 noise-exposed subjects and 176 subjects with a history of noise exposure but with a normal audiogram. Findings were also compared with those in 310 young military recruits with no reported history of noise exposure and normal bilateral audiogram. In general, the features of noise-induced emissions loss (NIEL) closely resembled the behavioural NIHL parameters: both were bilateral and both affected primarily the high frequencies, with a "notch" at around 3 kHz in the DPOAEs. On average, CEOAEs were recorded up to 2 kHz, indicating that up to this frequency range (speech area), cochlear functioning is intact and the hearing threshold s better than 25 dBHL. A clear association between the OAEs and the severity of the NIHL was noted. As the severity of NIHL increased, the emissions range became narrower and the amplitude smaller. OAEs were found to be more sensitive to noise damage than behavioural audiometry. NIEL was found in subjects with normal audiograms but with a history of noise exposure. Owing to their objectivity and sensitivity, OAEs may sometimes provide indispensable information in medico-legal cases, in which the configuration of the audiometric threshold is needed to obtain an accurate diagnosis of NIHL and compensation is proportional to the severity of NIHL. Furthermore, OAE testing between ears with and without NIHL revealed a high sensitivity (79 - 95%) and specificity (84 - 87%). This study shows that OAEs provide objectivity and greater accuracy, complementing the behavioural audiogram in the diagnosis and monitoring of the cochlear status following noise exposure.     

hOGG1、APEX1和XRCC1基因单核苷酸多态性与噪声性听力损失的关联研究

目的 探讨人类8-羟基鸟嘌呤糖苷酶基因（hOGG1）、脱嘌呤脱嘧啶核酸内切酶1基因（APEX1）、X射线损伤修复交叉互补基因（XRCC1）多态性与中国汉族人群噪声性听力损失（noise-induced hearing loss,NIHL）的易感关联性。
方法 以江苏省某化纤公司下属3个子公司接触噪声的作业工人为研究对象,结合工作场所噪声声级测量结果和工人纯音测听结果,筛选病例组585人和对照组619人。获取两组人群周围血基因组DNA,采用TaqMan探针法对所选基因的单核苷酸多态性位点进行基因分型。
结果 共筛选3个候选基因:hOGG1、XRCC1和APEX1。logistic回归分析结果显示:在显性模型中,相比GG基因型,rs2072668 CC+CG基因型可能是噪声性听力损失发病的危险因素,其调整的OR值及95% CI值为1.40（1.10~1.78）;在90~95 dB（A）·年累积噪声暴露量下,相比GG基因型,rs2072668位点CC+CG基因型可能是噪声性听力损失发病的危险因素,其调整的OR值及95% CI值为2.11（1.16~3.82）;在 < 90 dB（A）·年累积噪声暴露量下,相比TT基因型,rs 1130409 GG+GT基因型可能是噪声性听力损失发病的危险因素,其调整的OR值及95% CI值为2.76（1.13~6.73）。单体型分析结果显示,CTG（rs2072668-rs1799782-rs2230409）可能是噪声性听力损失发病的危险因素,相比对照组,其调整OR值及95% CI值为1.78（1.21~2.61）。
结论 rs2072668 CC+CG基因型增加了噪声作业工人患NIHL的风险,提示hOGG1基因单核苷酸多态性可能与NIHL易感性有关。
     

Audiometric "early flags" for occupational hearing loss

OBJECTIVE: OSHA criteria for recording occupational noise-induced hearing loss (NIHL) do not ensure early detection, yet scientific consensus is lacking regarding optimal "early flags" for NIHL. This study compares early flag metrics to the subsequent development of recordable hearing loss. METHODS: In a longitudinal analysis of industrial audiograms, we calculated time from flag event to recordable hearing loss as well as 10 year risk of recordable hearing loss following flag occurrence. RESULTS: The 10 dB non-age-corrected STS and the 8 dB age-corrected shift at 2, 3, and 4 kHz optimally combined positive predictive value and length of time to recordable hearing loss. CONCLUSIONS: Professionals supervising audiometric surveillance must balance predictive value of early flags with timeliness of detection. This study provides a framework for validation and selection of audiometric early flags in hearing conservation settings.     

Efficacy of an intervention to promote use of hearing protection devices by firefighters

Numerous cases of hearing loss consistent with noise-induced damage were noted among firefighters in the city of Columbia, MO. A survey of firefighting vehicles in operation showed that the firefighters were exposed to excessive noise levels and put at risk for noise-induced hearing loss (NIHL). Audiologic evaluation showed that 36 percent of the firefighters had moderate or severe hearing loss (a threshold of 40 decibels (dB) or more at 3,000, 4,000, or 6,000 hertz (Hz) in either ear). An educational program on NIHL was then carried out to increase the use of hearing protection devices (HPDs) by firefighters, followed by an evaluation of the intervention. The educational intervention successfully increased knowledge of NIHL, positive attitudes toward HPDs, and resulted in more frequent use of HPDs. After the intervention, 85 percent of firefighters regularly used HPDs compared with 20 percent before the intervention. Recommendations are made for fire departments to reduce the risk of NIHL.     

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

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

Hearing status among cabin crew in a Swedish commercial airline company

Purpose  To study hearing loss in commercial airline cabin crew (CC). Methods  Totally 155 male and 781 female CC (n = 936) in a Swedish airline company underwent repeated audiometric tests during 1974–2005. The last test was used to study hearing loss. The mean test values at 3, 4, 6 kHz were used for the ear with worse hearing loss. Data were compared with a Swedish population (n = 603) who were not occupationally exposed to noise. Equivalent noise levels (Leq) were measured in different aircraft. Results  Leq was 78–84 dB (A), maximum A-weighted exposure was 114 dB. Median values for all ages were close to the reference group. No association was found between years of employment and hearing loss, when adjusting for age and gender by multiple logistic regression analysis. Conclusion  Cabin crew are exposed to equivalent noise levels below the current Swedish occupational standard, and have normal age-matched hearing threshold levels.     

职业噪声暴露与吸烟联合作用对听力影响的研究进展

职业噪声暴露所导致的职业性听力损伤是世界范围内的主要职业性疾病，但噪声并不是引起职业性听力损伤的惟一因素。研究发现吸烟也是听力损伤的重要危险因子之一，吸烟可能通过损伤内耳毛细胞及导致内耳组织缺氧加重噪声暴露所导致的听力损伤。     

学校噪声的污染现状及其行为毒理学研究

本文从环境卫生学和行为毒理学的角度，研究了学校噪声的来源、污染现状及其对实验动物和中小学师生行为的影响。结果表明，学校噪声污染严重，等效声级平均为６２ｄＢ（Ａ），超过６５ｄＢ（Ａ）的学校占被调查学校的３３．３％。噪声主要来源于交通噪声。根据行为毒理研究结果，提出学校室外１ｍ噪声标准的建议值（Ｌｅｇ）为５５ｄＢ（Ａ）。本研究为制订学校噪声标准和噪声防治提供了科学依据。