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.
It also estimated that in middle-age as many as 9% of women and 24% of men were affected, undiagnosed and untreated.The costs of untreated sleep apnea reach further than just health issues. It is estimated that in the U.S., the average untreated sleep apnea patients annual health care costs $1,336 more than an individual without sleep apnea. This may cause $3.4 billion/year in additional medical costs. Whether medical cost savings occur with treatment of sleep apnea remains to be determined. Frequency and population
Sleep disorders including sleep apnea have been become an important health issue in the United States. Twenty-two million Americans have been estimated to have sleep apnea, with 80% of moderate and severe OSA cases undiagnosed.OSA can occur at any age, but it happens more frequently in men who are over 40 and overweight. History
A type of CSA was described in the German myth of Ondines curse where the person when asleep would forget to breathe. The clinical picture of this condition has long been recognized as a character trait, without an understanding of the disease process. The term "Pickwickian syndrome" that is sometimes used for the syndrome was coined by the famous early 20th-century physician William Osler, who must have been a reader of Charles Dickens.