Carha's notch in audiometry is seen in
In some cases of otosclerosis, there is a dip in bone conduction curve. It is different at different frequencies but maximum at 2000Hz and is called Carha's notch. (5db at 500Hz, 10db at 1000Hz, 15db at 2000Hz and 5db at 4000Hz) Ref: Diseases of EAR, NOSE and THROAT by PL Dhingra; 7th Edition; Page no.96
Ossicular discontinuity
Haemotympanum
Otomycosis
Otosclerosis
Ear