<prompt> In noise induced hearing loss , audiogram shows a Boilers notch at ?1000 Hz2000 Hz3000 Hz4000 Hz  <response>: Noise induced hearing loss Boiler notch at 4000 HZ Max seen at 3000 - 6000 HZ Sterocilia of outer hair cells are 1st to be affected . Carhas notch - dip is present at 2000 HZ .seen in otosclerosis 