Auditory fatigue is seen at: (A) 90 dB, 4000Hz, (B) 110 dB, 4000Hz, (C) 130 dB, 4000Hz, (D) 150 dB, 4000Hz
Answer is A. Auditory fatigue occurs at 90dB, 4000Hz. 90dB for 8hour a day for 5weeks is the maximum safe limit. (Ref: Diseases of EAR, NOSE AND THROAT by PL DHINGRA - 6th Edition)