any structural anomaly in the sensory cells of the organ of Corti which are in synaptic contact with sensory as well as efferent fibers of the auditory nerve; there are three rows of columnar outer hair cells largely surrounded by cortilymph and supporting phalangeal cells; the apical end of each cell is anchored to the cuticular plate and about 100 stereocilia arranged in a V-shaped pattern extend from the cell's surface through the cuticular plate into the tectorial membrane