It is generally accepted that Carhart’s “dip” in otosclerosis develops as a result of the absence of the middle ear osteotympanic component of the bone conduction due to a block of the oval window. In the submitted article the authors summarize reasons which cast doubts on this view. The authors assume that Carhart’s “dip” oceurs as a result of the mechanical and hydrodyna- mic changes in the cochlea.

        Key words: Carhart’s “dip”, otosclerosis, bone conduction hearing threshold.