Caraha's notch: Is classically found in bone conduction audiograms of patients with otosclerosis. This is actually a dip centered around 2000 Hz. Some authors consider carha's notch to be an aifact. This notch is closely related to the carha's effect.Carha's effect: was initially described following successful stapes surgery. There was an over closure of air bone gap following successful surgery. Classically this effect lead to an improvement in hearing levels paicularly at 2 KHz frequency levels.