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Unilateral hearing loss |
| Unilateral hearing loss Classification and external resources |
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| ICD-10 | H90.1, H90.4, H90.7 |
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Unilateral hearing loss (UHL) or single-sided deafness (SSD) is a type of hearing impairment where there is normal hearing in one ear and impaired hearing in the other ear.
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Patients with unilateral hearing loss have difficulty in
In quiet conditions, speech discrimination is approximately the same for normal hearing and those with unilateral deafness1; however, in noisy environments speech discrimination varies individually and ranges from mild to severe23.
Known causes include physical trauma, acoustic neuroma, microtia, meningitis, or mumps (Epidemic parotitis).
A 1998 study of schoolchildren found that per thousand, 6-12 had some form of unilateral hearing loss and 0-5 had moderate to profound unilateral hearing loss. It was estimated that in 1998 some 391,000 school-aged children in the United States had unilateral hearing loss.4
Profound unilateral hearing loss is a specific type of hearing impairment when one ear has no functional hearing ability (91dB or greater hearing loss). People with profound unilateral hearing loss can only hear in monaural (mono). It is known to cause:
Learning of the central nervous system by "plasticity" or biological maturation over time does not improve the performance of monaural listening5.
A recent study compared the CROS hearing aid with a bone anchored CROS system and found that the latter yields greater benefit on the deaf ear8.
When wearing stereo headphones, people with unilateral hearing loss can hear only one channel, hence only half of the components of the music, e.g., bass or piano, but not both (although most modern recordings feature amplitude difference in instruments between the channels, rather than complete silence in one channel and full volume on the other, with respect to one specific instrument). The need for headsets for cellphones and VOIP communication has made monaural headphones, which often combine stereo to mono sound, readily available to solve the problem. Stereo headphones may also be connected to a sound source with a stereo-to-monaural adapter to achieve a similar effect (the two stereo channels going into one headphone).
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