There is an estimated 10 million Americans that suffer from permanent, irreversible hearing loss from their workplace. Many soldiers come back from battle with this damage, mainly from the high sound levels of their weapons that they are exposed to. The U.S. government spends over $250 million a year in compensation to those whose hearing has been damaged. There are current medicines that have proven to help eliminate or lessen the affects from certain types of noise induced hearing loss, specifically from prolonged expose. A noise exposure system was needed to be built for impulse noise induced hearing loss testing. That would help lead to a medicine for impulse noise induced hearing loss. A system was designed and built to replicate the noise signal of an M-16 rifle. The system's digital noise signal produced was comparable to the recorded M-16 noise signal, which reached a 145 dB level. Testing showed that the relationship between the amplitude and the maximum levels measured were linear. Sound levels of the produced impulse waves had a maximum limit of approximately 160 dB. The system was designed with the idea of customization. There are multiple parameters that can be adjusted to best fit the testing needs. The noise exposure system will be used by researchers in the SIU school of medicine in research designed to test the effect. The results from Dr. the research will validate the effectiveness of the noise exposure system that was built.

Thesis (M. Phil.)--University of Hong Kong, 1983.

Background: Noise is one of the most important forms of environmental pollution among developed and developing countries. A report from UK National Study of Hearing estimated that around 440 million people suffer from noise induced hearing loss in EU countries with 1–1.6 million disability-adjusted life year lost. In China, the Second China National Sample Survey on disability in 2007 revealed that about 27.8 million people suffered from hearing impairment, and 73.4% of which (about 20 million) were diagnosed with disability. The prevalence of hearing impairment was estimated to be 2.1% in the general population, and increased to 11.0% among those aged greater than 65 years. Objective: To find out the effect of earplug on noise induced hearing loss (NIHL), as well as understanding the source and exposure of noise in the industry, to estimate the prevalence of NIHL in factories with noise exposure, to analyze relationships between NIHL and age, sex, dose and duration of occupational noise exposure, type of work, use of hearing protection products, education level and other factors. Significant risk factors identified were used to provide evidence-based recommendations in prevention and control of NIHL. Study Design: Retrospective, cross-sectional study Method: A total of 1874 workers exposed to noise in a compressor factory in Guangzhou, China were included. Between September 2011 and January 2012, physical examination including a screening program of hearing loss, pure tone audiometry test were carried out among workers including information on age, sex, work types, noise exposure level, exposure time, as well as the questionnaire about earplug using status, status of using ear products report by company, smoking status, education level, discharge of ear, history of herpes zoster, history of using ototoxic drugs, history of ear surgery, family history of NIHL, systolic blood pressure, diastolic blood pressure. The outcome variable is the audiometric mean value which reflects hearing status of the subjects. Subgroup differences in mean value of audiometry were compared by independent sample t-test. Multiple linear regression and logistic regression models were used to evaluate associations between earplug use and NIHL, adjusted for other potential confounders. Factors associated with earplug use were also identified. Result: 1873 workers took part in the study (both physical examination and questionnaire) The prevalence of NIHL is 381 (20.3%) from study, and an average noise level of 83.5 dB was detected in the factory across different types of working place. The pure tone audiometric mean value (PTA) is 26.7 dB with a standard deviation of 4.8. The mean PTA value for those using earplug is 25.81 dB, which was significantly lower than those not using earplug with a mean PTA value of 1.54 dB (p < 0.001). A 0.962 mean difference is detected between noncontinuous earplug usage group and continuous usage group. Multiple linear regression model showed a dose response effect in use of earplug on NIHL, with an estimated mean PTA 1.49 dB (p-value <0.001) and 0.96 dB (p-value = 0.001) lower than those not using earplug at all. Hearing protective effect with part of dose response relationship is found in education level groups as well. Workers from technical school have a 5.974 dB lower of mean PTA, where the decrease is 3.909 dB in high school group, reference of primary level. Moreover, ever smokers show 1.557 dB higher on reference as nonsmoker. Other significant results can be found in family history of NIHL, ototoxic drug using, with statistical significant, respectively, with the direction of positive to NIHL, which shows harmful effect on workers’ hearing. Multivariable logistic regression model is used to find out factors associated with earplug usage. In the model, higher education level is found to be associated with higher earplug usage, especially among participants from technical schools, with an adjusted odds ratio (AOR) of 34.07, whereas those from high school group have an AOR of 12.35.(With Primary school group being the reference group.) Workers whose daily tasks involve phosphorus board, punching press, compressor are found to have a relatively low percentage on earplug usage compliance, with AOR of 0.55, 0.41, 0.23 respectively. (Those from machine shops are used as the reference group.) The result is in accordance with their positive correlation on NIHL. Conclusion: Use of earplug was found to be protective to NIHL. Factors such as education level, smoking status, discharge of ear, family history of NIHL and certain types of work were found to be associated with lower risk of NIHL. To protect hearing of the workers and reduce NIHL prevalence, provision of and education on hearing protection products and supervision of continuous use of earplug in noise exposed industry should be implemented. Occupational health monitoring to the enterprises should be enhanced by health sectors of Chinese government. Due to the limitation of retrospective design of this dissertation, further cohort studies are called for to provide stronger evidence of factors’ effect on NIHL. / published_or_final_version / Public Health / Master / Master of Public Health

Thesis (M. Sc.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves 39-43).

Thesis (M. Aud.)--University of Canterbury, 2009. / Typescript (photocopy). Includes bibliographical references (leaves 76-90). Also available via the World Wide Web.

Thesis (M. Sc.)--University of Hong Kong, 1995. / Includes bibliographical references (leaves 72-75).

ABSTRACT It is well documented that repetitive exposures to high intensity sound can cause acoustic trauma to the ear resulting in hearing loss, and that occupational noise is a significant cause of adult-onset hearing loss. Research world wide has indicated a significant number of workers with hearing loss attributed to noise exposure. Noise-Induced Hearing Loss (NIHL) claims are responsible for the majority of occupational disease payouts. The study was undertaken in order to determine the extent of hearing loss due to noise exposure that could be ascribed to excessive exposure to noise, and to describe the noise-induced hearing loss by severity, type of work, and area of work and duration of service. The cross-sectional study included 466 workers employed in a pulp and paper mill in KwaZulu Natal (KZN) South Africa. It involved the assessment of 932 individual audiograms to diagnose noise-induced hearing loss and the calculation of the percentage loss of hearing from pre placement to the year 2005. Audiometry results were presented for noise-induced hearing loss in relation to area of work, duration of service, categories of severity and age group. The prevalence of noise-induced hearing loss in the pulp and paper mill was 21% (98/466) and with 79% (368/466) of workers whose audiograms returned results not indicating NIHL. 75 workers were excluded due to workplace transfers. Type of work, area of work and years of service correlated significantly with a diagnosis of noise-induced hearing loss. As a department, the wood yard (which included the wood chipping facility, maintenance workers and workers with 10 – 20 years of service) showed the most significant association. In categories of severity 16.7% of workers suffering from NIHL fall in the ≤ 5 Percentage Loss of Hearing PLH category. This study has confirmed the findings of others that noise exposure is a significant hazard in industry and an effective noise control programme is the only way to reduce the risk of NIHL. _____________________________________________________________________

Thesis (M. Communication Pathology)--University of Pretoria, 2003. / Summary in English and Afrikaans. Includes bibliographical references.

Children suffering from noise-induced hearing loss could have disease burden such as communication difficulties, frustration, isolation as well as impaired self-cognition due to different degrees of hearing loss. Lack of hearing protection was the easiest way to tackle among the risk factors. Hence, the aim of this review is to review and synthesize existing evidence to show the effects of hearing conservation programs targeted on children and adolescents. Six studies included meeting strict requirements of inclusion and exclusion criteria. Significant improvements were shown in knowledge, attitude, intended behavior as well as hearing protective devices use regarding educational programs. However, limited effective consequence was shown in terms of audiometric threshold testing, thus, indicating limited effectiveness of educational programs in noise-induced hearing loss prevention. The results of hearing conservation programs were illustrated in details. And limitations as well as implications were discussed. / published_or_final_version / Medicine / Master / Master of Public Health

published_or_final_version / Industrial Engineering / Master / Master of Philosophy