A noise of 90 dB (A) SPL, 8 hours a day for 5 days per week is the maximum safe limit as recommended by Ministry of Labour, Govt. of India-Model rules under Factories act Noise induced hearing loss Hearing loss can result from damage to structures or nerve fibers in the inner ear that respond to sound. This type of hearing loss, termed "noise-induced hearing loss," is usually caused by exposure to excessively loud sounds and cannot be medically or surgically corrected. Noise-induced hearing loss can result from a one-time exposure to a very loud sound (at or above 120 decibels), blast, impulse, or by listening to loud sounds (at or above 85 decibels) over an extended period. The louder the sound, the shoer the time period before hearing damage occurs.