Hyperacusis

Hyperacusis is an increased sensitivity to sound and a low tolerance for environmental noise. Definitions of hyperacusis can vary significantly; it often revolves around damage to or dysfunction of the stapes bone, stapedius muscle or tensor tympani. It is often categorized into four subtypes: loudness, pain (also called noxacusis), annoyance, and fear.<ref name= "pmid25104073">Template:Cite journal</ref><ref name= "pmid25478787">Template:Cite journal</ref> It can be a highly debilitating hearing disorder.<ref name= "pmid24012803">Template:Cite journal</ref>

There are a variety of causes and risk factors, with the most common being exposure to loud noise.<ref name="pmid25104073" /> It is often coincident with tinnitus.<ref name="pmid25104073" /> Proposed mechanisms in the literature involve dysfunction in the brain, inner ear, or middle ear.<ref name= "pmid26139435" /><ref name="Liu-2015" /><ref name="Flores-2015" /><ref name= "Noreña 20182" /><ref name= "Fournier-2022a" /><ref name="Fournier-2022b" />

Little is known about the prevalence of hyperacusis, in part due to the degree of variation in the term's definition.<ref name= "pmid25104073" /><ref>Template:Cite journal</ref> Reported prevalence estimates vary widely, and further research is needed to obtain strong epidemiological data.<ref name="Musumano-2023">Template:Cite journal</ref>

Signs and symptoms

Hyperacusis symptoms can include an increased perception of the loudness of sounds (loudness hyperacusis), pain (noxacusis/pain hyperacusis/sound-induced otalgia), annoyance, and/or fear in response to sounds by which most people are unaffected. It may affect one or both ears.<ref name="Williams-2021a" /> The majority of patients experience bilateral symptoms but often have one ear that is more affected than the other. Annoyance hyperacusis is often considered synonymous with misophonia. Fear hyperacusis is often considered synonymous with phonophobia. Many researchers more narrowly define hyperacusis to only include loudness hyperacusis and pain hyperacusis.<ref name="Williams-2021a" />

Hyperacusis can also be accompanied by tinnitus. The latter is more common<ref name="BTA">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> and there are important differences between their involved mechanisms.<ref name="pmid24012803" />

Hyperacusis can result in anxiety and stress. Avoidant behavior is often a response to prevent the effects of hyperacusis and this can include avoiding social situations.<ref>Template:Cite journal</ref>

Loudness hyperacusis

Loudness hyperacusis is characterized by an increased perception of the loudness of sounds.<ref name="Williams-2021a" /> It is often associated with certain volumes and/or frequencies. It can occur in children<ref name=pmid29312994>Template:Cite journal</ref> and adults,<ref>Template:Cite journal</ref> and can be either "short-term" in a duration of weeks to less than a year before recovery, or, less commonly, "long-term," spanning years and in some cases becoming permanent. Sensitivity is often different between ears.<ref name="Pollard-2019">Template:Cite journal</ref>

Noxacusis

In some instances, hyperacusis is accompanied by pain, which is known as noxacusis.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Noxacusis is characterized by pain resulting from sounds, often initiated at certain volumes or frequencies.<ref>Template:Cite journal</ref> Pain can be immediate or delayed, and it sometimes persists for an extended period of time following exposure.<ref name="Pollard-2019"/> Pain can be acute or chronic, and is often described as stabbing, burning, throbbing, or aching. In healthy listeners, pain from sound is not typically experienced until the volume exceeds approximately 120 decibels.<ref name="Williams-2021a" />

Individuals experiencing noxacusis report less improvement over time and fewer benefits from sound therapy compared to individuals with loudness hyperacusis.<ref name="Williams-2021b">Template:Cite journal</ref>

Loudness discomfort level

The threshold of sound at which discomfort is initially experienced; measured in decibels (dB).<ref>Template:Cite journal</ref>

Setback

A setback is a temporary exacerbation of symptoms, a worsening of the perception of loudness or pain from sound, often due to a particular noise exposure.<ref name="Williams-2021a">Template:Cite journal</ref> Setback prevention is an important focus among those affected. Efforts to avoid setbacks commonly include using hearing protection and avoiding loud noises.<ref name="Pollard-2019"/> Pain hyperacusis patients experience setbacks more frequently than patients with loudness hyperacusis.<ref name="Williams-2021a" />

Associated conditions

Some conditions that are associated with hyperacusis include:<ref name="Baguley, 2003"/><ref>Template:Cite journal</ref> Template:Div col

• Acoustic shock
• Adverse drug reaction
• Anxiety
• Asperger syndrome
• Attention deficit hyperactivity disorder<ref>Template:Cite journal</ref>
• Autism spectrum
• Depression
• Endolymphatic hydrops<ref name="Møller 2011 p. 457">Template:Cite book</ref>
• Fetal alcohol spectrum disorder
• Hypothyroidism
• Lyme disease<ref name="Baguley, 2003"/>
• Migraine<ref name="Baguley, 2003">Template:Cite journal</ref>
• Ménière's disease
• Multiple sclerosis<ref name="Baguley 2007 p.">Template:Cite book</ref>
• Noise-induced hearing loss
• Posttraumatic stress disorder<ref name="Baguley, 2003"/>
• Severe head trauma<ref name="Baguley, 2003"/><ref name= "Granacher 2008 p.">Template:Cite book</ref>
• Sjögren syndrome<ref>Template:Cite journal</ref>
• Superior canal dehiscence syndrome
• Systemic lupus erythematosus<ref name="pmid20576373">Template:Cite journal</ref>
• Tay–Sachs disease<ref name="Desnick 2001 p.">Template:Cite book</ref>
• Temporomandibular joint disorder
• Tinnitus
• Tonic tensor tympani syndrome
• Trigeminal neuralgia
• Visual snow
• Williams syndrome<ref name="Baguley, 2003"/><ref name= "Zarchi">Template:Cite journal</ref>

Causes and risk factors

The most common cause of hyperacusis is overexposure to excessively high decibel (sound pressure) levels, which can cause acoustic trauma.<ref name="pmid25104073"/> An acoustic shock, which can lead to symptoms such as hyperacusis and ear pain, can also occur after exposure to an unexpected moderately loud to loud noise, even if this does not necessarily result in permanent cochlear damage.<ref name="Noreña 20182">Template:Cite journal</ref>

Some affected people acquire hyperacusis suddenly as a result of taking ototoxic drugs (which can damage the cells responsible for hearing), Lyme disease, Ménière's disease, head injury, or surgery. Others are born with sound sensitivity or develop superior canal dehiscence syndrome.<ref>Template:Cite journal</ref> Bell's palsy can trigger hyperacusis if the associated flaccid paralysis affects the tensor tympani, and stapedius, two small muscles of the middle ear.<ref name="Purves">Template:Cite book</ref> 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.<ref name="Carpenter">Template:Cite book</ref> Age may also be a significant factor, with younger patients exhibiting more severe hyperacusis.<ref name="Musumano-2023" />

Recently, it has been discovered that individuals with one copy of the GJB2 (Cx26) genetic mutation exhibit hearing that is more sensitive than average, akin to hyperacusis. These individuals appear to be at greater risk for damage from noise.<ref>Template:Cite journal</ref>

Some psychoactive drugs such as LSD, methaqualone, benzodiazepines, or phencyclidine can cause hyperacusis.<ref name="Musumano-2023"/><ref name= "Barceloux 2012 p.">Template:Cite book</ref> An antibiotic, ciprofloxacin, has also been seen to be a cause, known as ciprofloxacin-related hyperacusis.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Benzodiazepine withdrawal syndrome is also a possible cause.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>

Epidemiology

Prevalence estimates for hyperacusis vary widely in the literature, and further epidemiological data is needed. No gender differences have yet been established among hyperacusis patients. Hyperacusis appears to be more severe in younger patients.<ref name= "Musumano-2023" />

Possible mechanisms

Loudness hyperacusis

As one possible 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.<ref name="pmid26139435">Template:Cite journal</ref> The mechanism behind hyperacusis is not currently known, but it is suspected to be caused by damage to the inner ear and cochlea.

Noxacusis

Inner ear theory

Type II afferent fibers of the cochlear nerve are not responsible for hearing like the type I afferent fibers. They are thought to be cochlear pain neurons. Gain of function of these type II afferent fibers may be caused by a flood of ATP after hair cell damage.<ref name="Liu-2015" /><ref name= "Flores-2015" /> Now sensitized, they react to the small amount of ATP released during the normal process of hearing. This may result in pain.<ref name="Liu-2015">Template:Cite journal</ref><ref name= "Flores-2015">Template:Cite journal</ref>

Middle ear theory

Noreña et al. (2018) propose a model that may account for sound-induced pain and a constellation of other symptoms often experienced after an acoustic shock, acoustic trauma, and potentially other mechanisms of auditory damage. Symptoms may include a sense of fullness in the ear, tinnitus, and dizziness.<ref name="Noreña 20182"/><ref name="Fournier-2022a">Template:Cite journal</ref>

The model details how symptoms may be initiated by tensor tympani muscle damage or overload due to acoustic shock or trauma. Hypercontraction or hyperactivity of the muscle may cause an "ATP energy crisis." The muscle is then forced to create energy without sufficient oxygen, which results in the release of lactic acid into the middle ear space. This acidity can activate pain-sensing neurons. Muscle relaxation requires energy in the form of ATP. In the setting of low ATP, it is more difficult for the muscle to relax, which causes the cycle to continue. Via a cascade of events, the activated pain neurons can cause neurogenic inflammation, which may lead to additional pain. In this way, a "vicious circle" is created.<ref name= "Noreña 20182" /><ref name= "Fournier-2022b">Template:Cite journal</ref>

Pain from sound sometimes radiates to the face, scalp, and neck. This may be due to the trigeminocervical complex in the brainstem, which integrates input from and output to various regions of the head and neck, including the middle ear. Of note, the tensor tympani muscle is innervated by the trigeminal nerve. The model also explains how whiplash injuries, temporomandibular joint dysfunction, and other conditions affecting the head and neck regions may influence the function of the tensor tympani muscle and contribute to ear symptoms such as pain hyperacusis.<ref name="Noreña 20182" /><ref name= "Fournier-2022a" /><ref name="Fournier-2022b" />

Diagnosis

File:LDL-Audiogram.jpg

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.<ref name="pmid26029161">Template:Cite journal</ref>

The basic diagnostic test is similar to a normal audiogram. The difference is that, in addition to the hearing threshold at each test frequency, the lowest uncomfortable sound level is also measured. This level is called loudness discomfort level (LDL) or uncomfortable loudness level (ULL). In patients with hyperacusis this level is often considerably lower than in normal subjects, and usually across most parts of the auditory spectrum.<ref name="pmid25104073"/><ref name="pmid26029161"/> However, there is not a consensus regarding what constitutes a normal LDL. The relationship between LDL's and self-reported ability to tolerate sounds in everyday life in unclear.<ref name="Jahn-2022">Template:Cite journal</ref>

In addition to self-report questionnaires, audiologists may employ a variety of other techniques to evaluate auditory function in patients experiencing noise sensitivity. When conducting testing that involves the presentation of sounds, which may cause the patient discomfort or pain, it is vital to inform the patient of the volume and duration of sounds to be presented prior to testing. Care should be taken to begin with sounds of low volume, and volume should be increased gradually. The audiologist and patient should both be prepared to stop testing at any time, depending on the patient's symptoms.<ref name="Jahn-2022" />

Management and treatment

There are currently no evidence-based guidelines regarding the treatment of patients with hyperacusis. The majority of audiologists report insufficient formal education in this area, likely due in part to the current lack of consensus in the literature regarding definitions and treatment of hyperacusis.<ref>Template:Cite journal</ref>

Avoidance and hearing protection

File:Hyperacusis patient wearing ear protection.jpg

Hyperacusis patient wearing ear protection

Setback prevention and reduction of pain symptoms are high priorities among those with hyperacusis and noxacusis, which is often managed through a combination of controlling the environment so as to avoid loud sounds, soundproofing, and wearing hearing protection, such as earplugs and safety earmuffs.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Preliminary research has shown that individuals with pain hyperacusis can experience an exacerbation of their symptoms when not adequately protecting themselves against loud sounds.<ref name= "Pollard-2019" />

There are diametrically opposing views on avoiding overuse of hearing protection and silence. Some audiologists may advise against using hearing protection in normal sound environments, claiming it can cause or worsen hyperacusis. This is based on a study in healthy volunteers and not individuals with preexisting loudness or pain hyperacusis.<ref>Template:Cite journal</ref>

Sound therapy

Sound therapy is sometimes recommended for those with hyperacusis, though there is limited evidence supporting its use.<ref name="Sound therapy current recommendations">Template:Cite journal</ref> Its application among those with pain (noxacusis) should be used with caution. 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, some patients can rebuild (i.e., re-establish) their tolerances to sound.<ref name= "pmid25478787" /><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite book</ref> More research is needed on the efficacy of sound therapy techniques when hyperacusis is the primary complaint, rather than a secondary symptom, indicating that "no strong conclusions can be made" about its efficacy at this time.<ref name=pmid29312994/> Importantly, individuals with pain hyperacusis are more likely than individuals with loudness hyperacusis to report worsening of their condition after the use of sound therapy.<ref name="Williams-2021b" />

Cognitive behavioral therapy

Another possible treatment is cognitive behavioral therapy (CBT), which may also be combined with sound therapy.<ref name= "Baguley, 2003"/><ref>Template:Cite journal</ref> However, randomized controlled trials with active control groups are still needed to establish the effectiveness of CBT for hyperacusis<ref>Template:Cite journal</ref> and the usefulness of CBT for noxacusis is not yet demonstrated in the scientific literature.

Surgery

Studies have shown improved loudness discomfort levels in patients with hyperacusis after round and oval window reinforcement.<ref name=pmid29312994/>

A case of chronic ear pain associated with hyperacusis after exposure to loud noise at a concert was successfully treated with tympanic neurectomy.<ref>Template:Cite journal</ref>

Anecdotal medication data

The tricyclic anti-depressant clomipramine (brand name Anafranil) has been anecdotally useful for many people with hyperacusis. Both loudness hyperacusis and noxacusis have been successfully treated with this drug. A dosage of up to 200–250 mg daily for a sustained period of six to twelve months may be needed to cure hyperacusis. A possible mechanism of action of this drug is that clomipramine reduces reactions of the autonomic nervous system to sounds.<ref>Template:Cite journal</ref>

The drug ambroxol helps relieve the pain experienced by several pain hyperacusis patients.

Treatment for suicidal thoughts

Suicidal ideations are a risk factor in hyperacusis patients. Hashir et al. (2019) interviewed 292 patients and found that 15.75% had expressed suicidal ideations in the previous two weeks of the study. They recommend screening for these issues.<ref>Template:Cite journal</ref>

Society and culture

• Musician Jason DiEmilio, who recorded under the name Azusa Plane, had hyperacusis and ultimately went on to die by suicide due in part to his sensitivity to noise.<ref>{{#invoke:citation/CS1|citation

|CitationClass=web }}</ref>

• Dietrich Hectors, a hyperacusis sufferer in Belgium, took his life in 2009, after years of struggling with catastrophic hyperacusis and tinnitus.<ref name= "Noise Kills">Template:Cite newsTemplate:Cbignore</ref><ref>Template:Cite newsTemplate:Cbignore</ref> A local government in Belgium made a short film based on his life to warn others of the dangers of hyperacusis and tinnitus.<ref>Template:Cite newsTemplate:Cbignore</ref>
• 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.<ref>{{#invoke:citation/CS1|citation

|CitationClass=web }}</ref>

• Vladimir Lenin, the Russian communist revolutionary, politician, and political theorist, was reported seriously ill by the latter half of 1921, having symptoms possibly consistent with hyperacusis, such as regular headache and insomnia.<ref>Shub 1966, p. 426; Rice 1990, p. 187; Service 2000, p. 435.</ref>
• Musician Peter Silberman of The Antlers had hyperacusis and tinnitus which put his musical career on hold, until the conditions reduced down to a "manageable level".<ref>Template:Cite news</ref>
• Racing driver Wolfgang Reip developed severe hyperacusis after several noise traumas during his racing career.<ref>{{#invoke:citation/CS1|citation

|CitationClass=web }}</ref>

• Ludwig van Beethoven possibly suffered from hyperacusis alongside his hearing loss. In a letter, he wrote: "As soon as anybody shouts, I can't bear it. Heaven alone knows what is to become of me."<ref name="Beethoven">Template:Cite journal</ref>

• British writer Linda Stratmann suffers from hyperacusis and reports noises "cut through her like a scalpel."<ref>Template:Cite newsTemplate:Cbignore</ref>

• Japanese man Ohama Matsuzo suffered from hyperacusis, leading to him murdering three neighbours over the sound of a piano.<ref>Template:Cite book</ref>

See also

• Auditory system
• Health effects of noise pollution
• Tinnitus
• Misophonia
• Otoacoustic emission
• Safe listening
• Sensory processing sensitivity
• Recruitment (medicine)
• World Hearing Day
• Hearing Health Foundation

External links

• Hyperacusis Research, Ltd.
• Hyperacusis Central Website
• Hyperacusis Central YouTube

Further reading

• Template:Cite book
• Template:Cite book