A study of noise exposure and noise induced hearing loss among workers at wood manufacturing industries in Shah Alam, Selangor / Rohaizat Mohd Noordin

Noise is unwanted sound and when people are exposed to the higher levels of noise it can damage the ear. Exposure to high levels of noise that exceed safe levels can lead to noise induced hearing loss which is a major hazard in many workplace and in society. The National Institute of Occupational Safety and Health estimates that more than 30 million worker (almost 1 in 10) are exposed to unsafe noise levels on the jobs. Wood manufacturing industries workers work in an environment which exposed to machineries noise makes the issue of damaging ears and hearing loss. A cross sectional study has been carried out to determine the relationship between noise exposure and hearing loss among 38 exposed workers (n=38). Respondent were selected based on their work process (stratified random sampling). Noise measurement has been done using the sound level meter at four (4) points at every factory involved (10). Noise dosimeter were used to measure personal exposure (TWA for 8 hours) and for this purpose 38 workers being selected (n=38). A structured questionnaire also being distributed to 38 workers that workers to identify the health effects (n=38). Audiometric test have been done to the 38 workers with supervision by OSH Doctor. Result shown there is no significant difference between right ear (p=0.122) and left ear (p=0.317) in noise exposure levels among exposed workers [85 dB to > 90 dB (A)]. Hearing loss symptoms shown significant difference for buzzing in the ear (p=0.000), difficulty to hear in noisy environment (p=0.000), raising the voice to communicate (p=0.000) and raising the radio volume after work (p=0.000). Audiometric testing results had shown that the group developing NIHL with 63.2%. Study also found there is no significant association between noise exposure level and noise-induced hearing loss for the group (p=0.000). This is supported by direct observation where 60% of exposed workers wore hearing protection device (HPD) as required. Since evidence indicated that they were symptoms and development of hearing loss, audiometric testing is suggested to be performed within the first six months of employment to monitor workers hearing ability.