Hyperacusis

Hyperacusis is a highly debilitating and relatively uncommon hearing disorder characterized by an increased sensitivity to certain frequencies and volume ranges of sound (a collapsed tolerance to usual environmental sound). A person with severe hyperacusis has great difficulty tolerating many everyday sounds, which are perceived by the person as uncomfortably loud and sometimes physically painful. The prevalence of hyperacusis is 1 in 50,000 people.

Hyperacusis is often coincident with tinnitus. However, tinnitus is more common and there are important differences between their involved mechanisms.

Signs and symptoms

In hyperacusis, the symptoms are ear pain, annoyance, distortions, and general intolerance to many sounds that most people are unaffected by. Crying spells or panic attacks may result from the experience of hyperacusis. It may affect either or both ears. Hyperacusis can also be accompanied by tinnitus. Hyperacusis can result in anxiety, stress and phonophobia. Avoidant behavior is often a response to prevent the effects of hyperacusis and this can include avoiding social situations.

The University of Iowa proposed four sub-categories of the condition:

• pain: sufferers experience discomfort or pain in reaction to certain sounds, usually those that are loud or high in frequency. Pain can be felt in the form of stabbing, burning, coolness, or pain that radiates down the neck.
• loudness: sounds are perceived as louder than their actual decibel level.
• annoyance: certain sounds are irritating.
• fear: sufferers begin avoiding everyday sounds out of fear of triggering symptoms, often isolating themselves at home.

Associated conditions

Some conditions that are associated with hyperacusis include:

Causes

The most common cause of hyperacusis is overexposure to excessively high decibel (sound pressure) levels.

Some sufferers acquire hyperacusis suddenly as a result of taking ear sensitizing drugs, Lyme disease, Ménière's disease, 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. Bell's palsy can trigger hyperacusis if the associated flaccid paralysis affects the tensor tympani, and stapedius, two small muscles of the middle ear. Paralysis of the stapedius muscle prevents its function in dampening the oscillations of the ossicles, causing sound to be abnormally loud on the affected side.

Some psychoactive drugs such as LSD, methaqualone, or phencyclidine (angel-dust) can cause hyperacusis. An antibiotic, ciprofloxacin, has also been seen to be a cause, known as ciprofloxacin-related hyperacusis.

Neurophysiological mechanisms

As one important mechanism, adaptation processes in the auditory brain that influence the dynamic range of neural responses are assumed to be distorted by irregular input from the inner ear. This is mainly caused by hearing loss related damage in the inner ear. The mechanism behind hyperacusis is not currently known, but it is suspected to be caused by damage to the inner ear and cochlea. It is theorized that type II afferent fibers become excited after damage to hair cells and synapses, triggering a release of ATP in response. This release of ATP results in pain, sound sensitivity, and cochlear inflammation.

Diagnosis

Loudness discomfort levels (LDLs): group data of hyperacusis patients without hearing loss. Upper line: average hearing thresholds. Lower long line: LDLs of this group. Lower short line: LDLs of a reference group with normal hearing.

The basic diagnostic test is similar to a normal audiogram. The difference is that additionally to the hearing threshold at each test frequency also the lowest uncomfortable sound level is measured. This level is called loudness discomfort level (LDL), uncomfortable listening level (UCL), or uncomfortable loudness level (ULL). In patients with hyperacusis this level is considerably lower than in normal subjects, and usually across most parts of the auditory spectrum.

Treatment

One possible 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. Although patients might not always make a complete recovery, the use of broadband noise usually gives some of them a significant improvement in their symptoms, especially if this is combined with counseling.

Another possible treatment is cognitive behavioral therapy (CBT), which may also be combined with retraining therapy.

Notable cases

• Musician Jason DiEmilio of Azusa Plane had hyperacusis and ultimately went on to commit suicide. His story was told in BuzzFeed.
• Musician Stephin Merritt has 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 has hyperacusis and no longer tours with the band.
• American politician, 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, having hyperacusis and symptoms such as regular headache and insomnia.
• Musician Chris Singleton had hyperacusis, but made a full recovery. His story was told in The Independent.
• Musician Peter Silberman of The Antlers had hyperacusis and tinnitus which put his musical career on hold, but was quoted saying it died down to a 'manageable level' He has now resumed his musical career.
• Voice actor Liam O'Brien has hyperacusis, and is quoted as having lost sleep during the time of diagnosis.

See also

• Auditory system
• Hearing
• Misophonia
• Otoacoustic emission
• Photophobia
• Tinnitus
• Tinnitus masker

External links

Information Websites

A 2020 study by the NIHR Nottingham Biomedical Research Centre analyzed the content and quality of information of fifteen popular hyperacusis websites using the validated DISCERN questionnaire. The website Hyperacusis Focus achieved the highest overall DISCERN score. The reviewers found that Hyperacusis Focus and U.K. National Health Service websites were the most comprehensive online resources for health care professionals and patients, respectively. Wikipedia was judged useful for both health care professionals and patients.

Non-profit Organizations

Hyperacusis Research Limited is a 501(c)(3) non-profit charity dedicated to the development of effective treatments for hyperacusis and to funding research which will eliminate the underlying mechanisms that cause hyperacusis.

Hearing Health Foundation is a non-profit with a mission to prevent and cure hearing loss and tinnitus through groundbreaking research and to promote hearing health.