diplacusis

Diplacusis, also known as diplacusis binauralis, binauralis disharmonica or interaural pitch difference (IPD), is a hearing disorder whereby a single auditory stimulus is perceived as different pitches between ears. It is typically experienced as a secondary symptom of sensorineural hearing loss, although not all patients with sensorineural hearing loss experience diplacusis or tinnitus. The onset is usually spontaneous and can occur following an acoustic trauma, for example an explosive noise, or in the presence of an ear infection. Sufferers may experience the effect permanently, or it may resolve on its own. Diplacusis can be particularly disruptive to individuals working within fields requiring acute audition, such as musicians, sound engineers or performing artists.

==Diplacusis of pure tones== The term diplacusis has been used in cases which people with unilateral cochlear hearing losses or asymmetrical hearing losses, the same tone presented alternately to the two ears may be perceived as having different pitches in the two ears. The magnitude of the shift can be measured by getting the subject to adjust the frequency of a tone in one ear until its pitch matches that of the tone in the other ear. On presentation of a single tone alternating between ears (i.e. 1000 Hz left, 1000 Hz right, 1000 Hz left, ...), a given person will consistently mismatch these sinusoids the same amount between trials if doing a pitch-matching task. For example, a 1000 Hz tone in an unaffected ear may be heard as a slightly different pitch in the opposite ear, or have an imperfect tonal quality in the affected ear.