Diplacusis

Diplacusis is defined as the different perception of a sound in terms of either pitch (A) or time (B) (Moore, 2007; Shambaugh, 1940).

A. Diplacusis – pitch difference

B. Diplacusis – time difference

It can be:

unilateral (affects only in one ear) or
bilateral (it affects both ears)

The latter, binaural diplacusis, is the most common type of the condition.

It occurs when a person exposed to a given tone/ sound of a certain frequency perceives that tone differently in each ear and at different frequencies. Diplacusis is mainly associated with inner ear dysfunction (Knight, 2004)

Diplacusis in the general population

The rate of diplacusis in the general population is not yet identified. It is important to emphasize that diplacusis between the two ears in normal hearing individuals ranges from 3% to 7%. In recent studies, even a difference of one semitone between the ears is considered to be within normal limits (Colin et al., 2016).