Carhart's notch is seen in-

Ans. is 'b' i.e., Otosclerois Pure tone audiometry in otosclerosiso Shows loss of air conduction, more for lower frequencies with characteristic rising patterno Bone conduction is normal. However in some cases, there is a dip in bone conduction curve which is maximum at 2000 Hz (2 KHz) and is called the Carhart's notcho Dip in bone conduction in otosclerosis (Carhart's notch) - 2000 Hzo Dip in noise induced hearing loss (Acoustic dip) - 4000 Hz