<prompt> Auditory fatigue is seen at90 dB, 4000Hz110 dB, 4000Hz130 dB, 4000Hz150 dB, 4000Hz  <response>: 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 