<prompt> In otosclerosis Carharts notch dips at:1000 Hz in AC1000 Hz in BC2000 Hz in AC2000 Hz in BC  <response>: d 2000HzinBCRef. Shambaugh, 6th ed., 532In otosclerosis the dip at 2000Hz is seen in bone conduction curve which is known as Carharts notch. Mnemonic: Carharts in Bone Conduction, CBC. 