|Classification and external resources|
Hyperacusis (or hyperacousis) is a debilitating hearing disorder characterized by an increased sensitivity to certain frequency and volume ranges of sound (a collapsed tolerance to usual environmental sound). A person with severe hyperacusis has difficulty tolerating everyday sounds, some of which may seem unpleasantly or painfully loud to that person but not to others.
It can be acquired as a result of damage sustained to the hearing apparatus, or inner ear. There is speculation that the efferent portion of the auditory nerve (olivocochlear bundle) has been affected (efferent meaning fibers that originate in the brain which serve to regulate hearing). This theory suggests that the efferent fibers of the auditory nerve are selectively damaged, while the hair cells that allow the hearing of pure tones in an audiometric evaluation remain intact. In cases not involving aural trauma to the inner ear, hyperacusis can also be acquired as a result of damage to the brain or the neurological system. In these cases, hyperacusis can be defined as a cerebral processing problem specific to how the brain perceives sound. In rare cases, hyperacusis may be caused by a vestibular disorder. This type of hyperacusis, called vestibular hyperacusis, is caused by the brain perceiving certain sounds as motion input as well as auditory input.
Although severe hyperacusis is rare, a lesser form of hyperacusis affects musicians, making it difficult for them to play in the very loud environment of a rock band or orchestra which previously gave them no problems. It also makes attendance at loud discos or live events difficult for a portion of the population, given that sound levels at such events usually exceed recommended safe levels of exposure. This is a problem which may be caused by genetic differences, stress or ill-health, or by abnormal responses in the tensor tympani (tonic tensor tympani syndrome) and stapedius muscles, which function in the normal acoustic reflex response that protects the inner ear from loud sounds.
Signs and symptoms
In hyperacusis, the symptoms are ear pain, annoyance, and general intolerance to many sounds that most people are unaffected by. Crying spells or panic attacks may result from the experience of hyperacusis. Hyperacusis may affect either or both ears. As many as 86% of people with hyperacusis also have tinnitus. Hyperacusis can result in anxiety, stress and phonophobia. Avoidant behaviour is often a response to prevent the effects of hyperacusis and this can include avoiding social situations.
A person with hyperacusis might be startled by very low sound levels. Everyday sounds like shutting doors, ringing phones, television, running water, ticking clocks, chewing gum, cooking, normal conversation, eating, dishes, and other sounds will cause varying levels of annoyance and can potentially pain the ears. In many people with hyperacusis, an increased activity develops in the tensor tympani muscle in the middle ear as part of the startle response to some sounds. This lowered reflex threshold for tensor tympani contraction is activated by the perception or even anticipation of loud sound, and is called tonic tensor tympani syndrome (TTTS). In some people with hyperacusis, the tensor tympani muscle can contract just by thinking about a loud sound. Following exposure to intolerable sounds, this contraction of the tensor tympani muscle tightens the ear drum, which can lead to the symptoms of ear pain/a fluttering sensation/a sensation of fullness in the ear (in the absence of any middle or inner ear pathology).
Sometimes hyperacusis can affect the vestibular system giving problems of balance, and this is referred to as vestibular hyperacusis. Vestibular hyperacusis, can also involve feelings of dizziness, nausea, or a loss of balance when sounds of certain pitches are present. For instance, people with vestibular hyperacusis may feel like they are falling and as a result involuntarily grimace and clutch for something to brace themselves with. The degree to which a person is affected depends on not only the overall severity of the symptoms but also whether the person can detect sounds in that frequency range at the volume in question, as well as on the person's preexisting muscle tone and severity of startle response.
The most common cause of hyperacusis is overexposure to excessively high decibel levels (or sound pressure levels). Some come down with hyperacusis suddenly as a result of acoustic shock as by firing a gun, having an airbag deploy in their car, experiencing any extremely loud sound, taking ear sensitizing drugs, Lyme disease, Ménière's disease, temporomandibular joint disorder, head injury, or surgery. Others are born with sound sensitivity, develop Superior Canal Dehiscence Syndrome, have had a history of ear infections, or come from a family that has had hearing problems. The Diagnostic and Statistical Manual of Mental Disorders (DSM) that is published by the American Psychiatric Association lists hyperacusis as one of the possible signs indicating phencyclidine (PCP or Angel-dust) intoxication.
Causes include, but are not limited to:
The most common treatment for hyperacusis is retraining therapy which uses broadband noise. Tinnitus retraining therapy, a treatment originally used to treat tinnitus, uses broadband noise to treat hyperacusis. Pink noise can also be used to treat hyperacusis. By listening to broadband noise at soft levels for a disciplined period of time each day, patients can rebuild (i.e., re-establish) their tolerances to sound. When seeking treatment, it is important that the physician determine the patient's Loudness Discomfort Levels (LDL) so that hearing tests can be adjusted accordingly (brainstem auditory evoke response). If people have access to medical care, steroids are used to treat hyperacusis within 72 hours of the onset of the condition.
- Ludwig van Beethoven suffered from hyperacusis, alongside tinnitus and hearing loss.
- Musician Jason DiEmilio of Azusa Plane suffered from hyperacusis. His story was told in BuzzFeed.
- Musician Stephin Merritt suffers from monaural hyperacusis in his left ear, which influences the instrumentation of his band, The Magnetic Fields, leads him to wear earplugs during performances and to cover his affected ear during audience applause.
- Musician Laura Ballance of Superchunk suffers from hyperacusis and no longer tours with the band.
- Chess legend Bobby Fischer is said[by whom?] to have had hyperacusis, and he needed total silence in order to concentrate on his games.
- American politician, LGBT activist, and film producer Michael Huffington has mild hyperacusis and underwent sound therapy after finding that running tap water caused ear pain.
- Russian communist revolutionary, politician, and political theorist Vladimir Lenin was reported seriously ill by the latter half of 1921, suffering from regular headache, insomnia and hyperacusis.
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- Anxierty caused hyperacusis
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- Shub 1966, p. 426; Rice 1990, p. 187; Service 2000, p. 435.
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- "Decreased Sound Tolerance", by Pawel J. Jastreboff and Margaret J Jastreboff, in: "Tinnitus: theory and management", ed. James Byron Snow, 2004, ISBN 1-55009-243-X
- "Hyperacusis Focus". A comprehensive informational website focused on assimilating all research related to hyperacusis.
- "Hyperacusis Research Foundation". Non-profit established to engage researchers, provide research grants, and increase public awareness.
- "Hyperacusis Network". An international support group established to care for individuals with a decreased sound tolerance (DST).