Introduction:
World Health Organization reported that 16% of the disabling hearing loss in adults is
attributable to occupational noise exposure [1]. The association between noise and noise-induced
hearing loss (NIHL) has been known since the 18th century. NIHL remains among the 10 leading
occupational diseases [2]. Noise-induced hearing loss usually progresses unnoticed until it begins
to interfere with communication, posing a serious safety hazard and a decrease in the quality of
life [3].The following categories are widely applied because they correspond to regulatory limits in
developed (usually 85 dB (A)) and many developing (usually 90 dB (A)) countries for 8-hour day:
Minimum noise exposure: 90 dB (A). [4]. Noise induced hearing loss is an irreversible and incurable
disease [5]. Noise exposure can create permanent threshold shifts (PTS); temporary threshold
shifts (TTS), permanent or temporary tinnitus and other physical side effects such as high blood
pressure. These types of hearing damage are often referred to as noise induced hearing loss
(NIHL) [6]. Noise induced hearing loss ranging from an average hearing threshold across 500,
1000, and 2000Hz of 25 dB or for OSHA [7].The higher frequencies are more commonly the first
to be damaged by the hazardous noise. Hazardous noise is generally any noise that is above 85
dBA [6].