HYPERACUSIS AND MISOPHONIA

Timothy C. Hain, MD • Page last modified April 3, 2023

Hyperacusis defined • Causes • Diagnosis • Treatment •Return to hearing page• tinnitus•phonophobia

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Hyperacusis Defined:

Hyperacusis is an abnormal sensitivity to sound. Katznenell and Siegel defined it as "increased sensitivity to sound .. that would not trouble a normal individual". A review of this condition as well as related ones is found in Henry et al (2022). Parmar and Prabhu defined it somewhat similarly - -"Hyperacusis is the hypersensitivity to auditory stimuli that would typically not affect those with hearing sensitivity within normal limits."

Other names for similar symptoms are phonophobia (fear of sounds), and misophonia (strong negative emotional reaction to specific sounds, see https://misophoniainstitute.org/what-is-misophonia/). These words are used somewhat interchangeably, without much precision. For example, hyperacusis in migraine is generally called phonophobia by neurologists. The term "pain hyperacusis" has also been introduced (e.g. Colluci, 2017), where the term "pain" has been substituted for "abnormal sensitivity". (seems like a bad definition to us).

Misophonia differs from hyperacusis in that it only applies to specific sounds, which need not be loud. For example, lip smacking... The lack of scaling of the response with loudness shows that it is misophonia. Ferrer-Tores et al (2022) reported "There is no consensus on the diagnostic criteria yet." -- so we really don't have a solid definition for misophonia eeither. Hmm.

Somewhere between 2 and 8% of the population report hyperacusis although some report as high as 15% (Andersson, G., N. Lindvall, et al., 2002; Baguley et al, 2011, Parmar and Prabhu, 2023). Parmar and Prabhu commented that "There is no universally accepted definition for what defines hyperacusis among kindred illnesses of poor sound tolerance. As a result, hyperacusis prevalence varies more, which has an impact on both assessment and treatment. " So workers in this field seem to have trouble defining what they are studying. Our guess is that the lower prevalence figure is the more accurate number as exaggeration of the frequency of symptoms can help papers get published, which introduces a bias.

In our clinical practice, ooking at a representative subset of our patient database, out of 33 patients with hyperacusis, 14 were men, and the average age was 48. Thus hyperacusis seems to be a disorder split roughly equally among genders and being first noticed, roughly at the age of 50.

Hyperacusis can be split into categories -- loudness hyperacusis, annoyance from louder sounds, and fear and pain -- which may not be associated with loudness, but just the sound.

Sometimes people call loudness hyperacusis, "supersonic hearing". In other words, it is not necessarily a bad thing. People with loudness hyperacusis can hear softer sounds than "normal" people. An example of this group are persons with SCD (superior canal dehiscence), who can hear internal noises (such as movement of their eyes) that other people can't.

The latter two categories are negative emotional responses generally associated with normal ability to perceive sound. In other words, these people have the same thresholds as everyone else, but they get upset earlier as the sound intensity is increased.

This is a review on hyperacusis written from the perspective of an otoneurologist (Dr. Hain). It emphasizes mechanisms for hyperacusis outside of inner ear disease.

The structures of the inner ear.

What causes hyperacusis ?

There are many causes of hyperacusis (Katznell and Siegel, 2001). There is not a single mechanism, and furthermore there is not a single "magic bullet" for hyperacusis.

Modeling of Hyperacusis.

The graph above (made with excel from made-up data), illustrates some general concepts about hyperacusis and what the terms "threshold", and "slope of perception vs. input". This graph is only meant to illustrate some general principles, and is not meant to say that everyone with, lets say, migraine, has the same picture. Also, it is not presently possible to quantify "perception" in a precise way, as perception is subjective.

Hyperacusis model

 

Normal people (the blue line), are defined as having a perception of sound equal the sound input intensity (in decibels). Thus their threshold is 0 dB, and their slope is 1.

Persons with migraine (the orange line), have the same threshold as other people, but they perceive sounds as being louder as they really are. Thus their slope is > 1. They have a reduced dynamic range (i.e. they don't tolerate loud noises as well as normal people).

Persons with recruitment (the gray line), are people who have damage to their inner ear, and can't hear very soft sounds (thus their threshold is higher). However, like migraine patients, the slope of their perception grows more rapidly with input. This results in a reduced dynamic range for sound that they tolerate. Sounds are more often "too soft", or "too loud".

 

Inner ear:

Hyperacusis with increased thresholds for sound (i.e. from ear damage)

Most hyperacusis is considered to be associated with damage to the inner ear, specifically the cochlea (the snail like thing on the right labeled '9'). However, the evidence is not strong. In our clinical experience, in hyperacusis, inner ear disease is much less common than other disorders that cause hyperacusis (e.g. migraine). Obviously, deaf people can't have hyperacusis (just as people without inner ear function don't experience motion sickness).

Thus as a general comment, there are opposed processes in hyperacusis associated with hearing loss -- the reduced hearing sensitivity makes hyperacusis less likely, and other changes, perhaps mainly related to adaptation to hearing loss, can make the remaining hearing input more annoying. As hearing loss progresses, there is less input for central circuitry associated with annoyance, and eventually loss of hyperacusis.

Inner ear hyperacusis
Causes
Irritability
Recruitment
Coincidence

 

When hyperacusis is accompanied by hearing loss, the association could be caused by irritability of the hair cells (such as in Meniere's disease), an increase in central gain (such a due to recruitment) or a mistake (i.e. confusion of an association with a cause). Recruitment is the jargon term used in audiology to describe the change in the input/output characteristics noted above.

In inner ear disease, loss of hearing at one frequency may be accompanied by increased sensitivity around the area of the hearing loss, resulting in hyperacusis. Thus a focal hearing loss may be more likely to cause hyperacusis due to an overly broad increase in central sensitivity. In support of this idea, Manohar et al (2017) noted that in rats given a high frequency hearing loss, they avoided low frequency noise.

According to Spyridakou et al (2012), difficulty with hearing speech in noise does not correlate with hyperacusis, but increased suppression of OAE's by noise does. This would support the conjecture that hyperacusis does not correlate with significant hearing loss, but might also relate the observation that if you can't hear something, you can't be sensitive to it.

Erinc and Derinsu compared LDLs and cortical evoked potentials in 20 hyperacusis sufferers and reported "Although the hyperacusis group is significantly different between groups in behavioural tests, the same cannot be said for electrophysiological tests. " In other words, these patients percieved sound to be louder, but the size of their electrical potentials in the brain was not different than controls. This would suggest that one cannot diagnose hyperacusis from cortical evoked potential, and also implies that these patients do not "hear better" than normal subjects.

Hyperacusis with reduced threshold to sound:

Hyperacusis occurs as in the SCD syndrome (Schmuziger, Allum et al. 2006), where people have better hearing than normal. If one can hear one's eyes move, SCD should be strongly considered. Hyperacusis for ones own eye movements -- i.e. an ability to hear ones eyes move, can also occur after surgery for tumors of the inner ear(Coad, Lockwood et al. 2001; Biggs and Ramsden 2002)

Loudness hyperacusis may occur in Bell's palsy -- here one of the small protective muscles in the ear, the stapedius, is paralyzed when the 7th nerve is damaged.

One would think that there would also be hyperacusis when the 5th nerve is damaged, paralyzing the bigger tensor tympani muscle.

8th nerve:

Hyperacusis can also arise from damage to the nerve between the ear and brain (8th nerve, labeled 6, auditory nerve). Examples here might be hyperacusis after a sudden hearing loss (attributed to viral damage to the hearing nerve), or microvascular compression syndrome. Hyperacusis is not a problem in completely deaf people (of course).

It may be that in a few cases, the hyperacusis here is not due to recruitment, but rather due to irritability of the nerve.

Vth nerve and complex regional pain syndrome (? midbrain?)

Drummond and Finch (2022), in studies of trigeminal antonomic cephalgias and complex regional pain syndrome reported in 2 patients (yes just 2), "Hyperalgesia to thermal and mechanical stimuli extended beyond the affected limb to encompass the ipsilateral forehead, and was accompanied by ipsilateral hyperacusis and photophobia." This suggests that hyperacusis might have some somatic modulation, as does tinnitus.

Drummond and Finch also reported on 31 patients with "complex regional pain syndrome", (2022), and stated that "Auditory discomfort thresholds were lower at several pitches on the CRPS-affected than contralateral side and lower at all pitches on the affected side than in controls. However, ipsilateral hyperacusis was not associated with psychophysical or physiological signs of cochlear damage. Instead, neural activity in the ipsilateral brainstem and midbrain was greater when repetitive click stimuli were presented on the affected than contralateral side and greater bilaterally than in controls. In addition, click-evoked potentials, reflecting thalamo-cortical signal transfer and early cortical processing, were greater contralaterally in patients than controls. Together, these findings suggest that hyperacusis originates in the ipsilateral brainstem and midbrain rather than the peripheral auditory apparatus of patients with CRPS. Failure of processes that jointly modulate afferent auditory signalling and pain (eg, inhibitory influences stemming from the locus coeruleus) could contribute to ipsilateral hyperacusis in CRPS. "

Brainstem:

The next step in the hearing cascade is the cochlear nucleus in the brainstem. Brainstem hearing disorders are rare, and it is also thought that brainstem hyperacusis is exceedingly rare. There have been a few cases reported however (Pfadenhauer, K., H. Weber, et al., 2001).

Guthrie et al (2022) reported that hyperacusis could be induced in rats after exposure to jet fuel, and suggested it was from brainstem changes.

Above, Drummond and Finch suggested that the midbrain was the localization for hyperacusis in complex regional pain syndrome.

Brain (central hyperacusis):

Misophonia (hatred of sound) involves specific sounds such as a spouse chewing or an office-mates keyboard clicking. These people are not bothered by the loudness of a sound, but rather by a specific sound pattern. Obviously, this is not due to any abnormality in the ear, but has to do with emotional reactions to specific sounds. Kumar et al (2017) documented that brain blood flow changes when people are irritated by sounds. This is not the same as documenting a cause-effect however. Jastreboff (2015) felt that misophonia was an example of classical conditioning, or in other words similar to Pavlov's dogs. If true, then one could presumably use learning theory to habituate, and one would expect this to gradually fade away. Rouw and Erfanian (2018), reported that misophonia is associated with "euphoric, relaxing, and tingling sensations with particular sounds or sights".

Aryal and Prabhu (2022) reviewed 12 other people's papers (this is called a systemic review), and they wrote "The result of the review revealed abnormal activation and connection among the different higher cortical structures in participants with misophonia. By signifying various neurophysiological and neuroradiological findings, the review confirms that misophonia is a neurophysiological disorder that may border between audiology, neurology, and psychiatry." Hmm. No so sure we need a review article to tell us this.

Psychological:

In the audiology community, the hypothesis is sometimes advanced that persons with hyperacusis have caused this problem themselves, by avoiding exposure to ordinary sounds. We find this implausible, but avoidance may add to the problem.

Furthermore, the audiology community often offers the hypothesis that "negative reinforcement caused by sound sensitivity and pain support hypervigilance, fear, and the development of psychopathology". (Colucci, 2017). The idea here, in essence, is that there is a positive feedback loop. When people are hurt by sound, they avoid sound, and as a consequence, they make themselves worse because their brain, in an attempt to hear more stuff, turns up the internal volume. We would not use this logic concerning someone who burns their hands on the stove and subsequently avoids fires, but we do with hyperacusis. Sometimes the words "breaking the cycle" is used, referring to the positive feedback loop (Colucci, 2017).

There is a large literature about using conditioning (called behavioral therapy) to reduce protective behavior patterns. One would think that CBT (cognitive behavioral therapy), would be effective in reducing distress (Juris et al, 2014)

As audiologists are unable to prescribe medications, it is not surprising that audiologists generally do not discuss medication treatment of anxiety or fear. However, physicians are allowed to prescribe medications for anxiety and depression, that can help in these situations.

Rarer sources of hyperacusis follow:

An obscure condition called "pyroluria (https://www.drbillsukala.com.au/nutrition/pyroluria-disease-myth/) " has been suggested to cause sensitivity to sound as well as smell and bright light. This syndrome has been discredited. The symptoms, however, are similar to migraine without headache.

Malingering of hyperacusis is also possible, as it is intrinsically a subjective symptom. See this page for more about malingering of hearing symptoms.

Persons with Williams syndrome all have hyperacusis (Klein). This genetic syndrome is characterized by cardiac defects, varying degrees of physical and developmental delay, stellate eye pattern, possible elevated serum calcium level, and elfin/pixie facial features. Exceedingly rare.

A case of Sandhoff disease was reported with hyperacusis (this is a GM2 ganglioside storage disorder), by Sahyouni et al, 2022. This is very very rare.

 

How is hyperacusis diagnosed ?

Jahn (2022) observed that "Outcomes of conventional audiologic tests are highly variable in the hyperacusis population and do not adequately capture the multifaceted nature of the condition on an individual level. This presents challenges for the differential diagnosis of hyperacusis, ". So there is room for improvement.

Persons with hyperacusis should be evaluated by a physician expert in ear disease, usually an otologist, neurotologist, or otoneurologist. There should be an examination of the ears. If there is also sensitivity to other sensory input (such as bright light, strong smells, motion) and/or headaches, a neurologist or otoneurologist would be the most appropriate as multiple sensory sensitivity is outside the spectrum of disease usually seen by ear doctors.

Audiogram prior to treatment for hyperacusis Hyperacusis for high frequencies
Audiogram showing low thresholds for uncomfortable noise, in patient with hyperacusis. Another audiogram showing more discomfort for high frequencies.

 

Hearing should be tested with an audiometer (i.e. not just tuning forks or other screeners), and the "UCL" audiogram should be obtained (uncomfortable loudness levels) Goldstein, B. and A. Shulman (1996). The UCL audiogram is a measure of discomfort from pure tones. Ideally, UCL levels should be around 80-90. Someone with hyperacusis might be around 50 as shown above.

For situations where there might be misophonia (dislike of a particular sound -- perhaps a soft one like smacking of the lips while eating), one would expect that it would be more productive to measure distress due to that particular sound, but this is not an easy task and generally not undertaken. Conventional audiometry is not especially helpful but there may be a clue when thresholds are very low -- Aazh et al (2022) reported that "The presence and frequency of reporting misophonia symptoms were not related to audiometric thresholds, except that a steeply sloping audiogram reduced the likelihood of frequent misophonia symptoms. Those with more frequent misophonia symptoms had lower values of ULLmin (the across-frequency average of ULLs for the ear with lower average ULLs) than those with less frequent or no reported symptoms. "

Otoacoustic emissions may be helpful (OAE's), especially the type of OAE's that are "diagnostic" rather than screening (we call these "sweep" OAE).  Contralateral suppression deficits in OAE have been reported. (Attius, 2005)

Acoustic reflexes may detect persons with paralysis of their stapedius.

A careful history should be taken, especially for migraine. In addition to headaches, one can recognize migraine because of sensitivity to other things beside sound. In addition to hyperacusis, persons with migraine often have photophobia (sensitivity to bright light), motion intolerance, sensitivity to strong smells, and sometimes even unusual cutaneous sensitivity (allodynia). The treatment approach for migraine is completely different than that for other types of hyperacusis.

Questionaires:

Parmar and Prabhu reviewed 23 articles on "assessment measures" to diagnose hyperacusis. They commented "There is no universally accepted definition for what defines hyperacusis among kindred illnesses of poor sound tolerance."

A psychological assessment may detect persons who have associated anxiety, depression or obsessive compulsive personality disorder (OCD). Those with auditory hallucinations may have a psychiatric disorder such as schizophrenia. Finding these things usually does not mean that the person's hyperacusis is caused by psychiatric problems, but rather may indicate a comorbidity. Usually it results in a medication recommendation.

A misophonia questionnaire was developed by Williams et al (2022). Others include the "amsterdam Misophonia Scale (Paunovic et al, 2022), and Khalfa's hyperacusis questionnaire (Altin et al, 2022).

management

How Is Hyperacusis Treated ?

Medications used in treatment of Hyperacusis

Medications may occasionally help lessen the hyperacusis even though no cause can be found. In general, we are not at all enthused about medication treatment as the side effects can be substantial and the results are often unimpressive. Dobie commented that medications were similar to placebo for tinnitus (1999), aside from those that modify the persons psychological responses. We think that the same is generally true for hyperacusis.

Medications to deal with the psychological fallout of hyperacusis is often useful -- antidepressants and anti-anxiety medications can be very helpful.

A list of drugs occasionaly useful in Hyperacusis includes:

Comment. Benzodiazepines and and antidepressants probably reduce anxiety, depression, or obsessive thinking about hyperacusis. Any sort of relief, however, is important. Anti migraine drugs act by preventing migraine, which commonly has hyperacusis (called phonophobia).

There is also evidence that serotonin pathways are implicated in hyperacusis as well as migraine, and SSRIs can be helpful. (Fioreti et al, 2016) We think that these, as well as anxiety medications are often worth trying.

Anti-seizure drugs (for example gabapentin, topiramate, levetiracetam) may be effective in persons with hyperacusis due to irritable neural pathways. These may be working on similar circuitry as is helpful for migraine. Generally speaking, seizure medications that work for migraine are also mood stabilizers, so they may also be helpful there.

Baclofen has been suggested to be useful in reducing responses in brainstem hyperacusis (Szczepaniak, W. S. and A. R. Moller, 1996). We have not found baclofen to be especially helpful.

Devices to treat hyperacusis

Comment: Ear plugs work by decreasing the amount of sound that the person is exposed to. This approach is generally frowned upon, because there is a feeling that wearing ear plugs over the long term will increase hyperacusis. It is thought that exposure to noise is habituating, and reducing the noise reduces the habituation effect. Nevertheless, as is the case with sunglasses when people are bothered by bright light, ear plugs or muffs can be very useful ( Sammeth, C. A., D. A. Preves, et al., 2000). Electronic noise suppression devices are used similarly, but they are less effective in reducing high-frequencies than passive methods.

Sound generators work by conditioning the nervous system to tolerate sound. They are similar in appearance to a hearing aid. Examples of maskers include the Starkey Silent-Star, and the GHI "Tranquil". These devices are readjusted every month to gradually accomplish desensitization. (Vernon, J. A, 1987).

A new treatment for hyperacusis that we have had some success with in our clinical practice in Chicago is insertion of specialized, heavy, ear tubes. With these tubes that reduce input from the higher pitches, something like semi-permanent ear plugs, some of our patients have had remarkable improvement. The improvement in hyperacusis seems to exceed the expected reduction in hearing. An example is shown below. These tubes can also be easily taken out. This is a minimally invasive approach to hyperacusis.

Audiogram prior to treatment for hyperacusis Post PE tube
Audiogram prior to ear tube insertion, showing low threshold for uncomfortable noise. Audiogram post specialized ear tube insertion, showing dramatic improvement in thresholds for uncomfortable noise.

 

Therapy to treat hyperacusis: Tinnitus Retraining Therapy (TRT).

TRT (Tinnitus Retraining Therapy) is a mixture of psychotherapy and masking (for tinnitus) or sound generators (for hyperacusis). (Jastreboff, 2000) TRT is presently a popular approach. It requires considerable time commitment. The psychotherapy part of TRT might be reasonably delivered by a psychotherapist and perhaps covered by insurance.

AIT or "Auditory integration training" consists of about 20 half-hour sessions over 10 days listening to specially filtered and modulated music. It is an unproven technique, that seems unlikely to do any harm. It is somewhat costly. It is based on Guy Bernard's book Audition Égale Comportement (English translation Hearing Equals Behavior).

Psychological help: Often, anxiety or depression which accompanies hyperacusis may be as big a problem as the hyperacusis itself. In this instance, consultation with a psychologist or psychiatrist expert in this field may be helpful. CBT is a psychological technique that may be helpful. A

If you can ignore hyperacusis rather than obsess about it, this may be the best way to handle it. Medications that help people with obsessive compulsive disorder (such as the SSRI family) may be helpful.

Surgery for hyperacusis

Surgery is rarely used for treatment of hyperacusis, in essence, because it is usually just a very expensive earplug that requires anesthesia. Most people are unwilling to give up their hearing to eliminate hyperacusis. Nevertheless, in persons where hearing is unusable, surgery has been reportedly successful. (Cherry and Brown ,1996).

Silverstein reported using "oval and round window reinforcement) for hyperacusis (Silverstein et al, 2016). This is a variant of a permanent ear plug.

We have encountered a few patients who had hyperacusis after loud noise, respond very well to a PE tube. We think that this is more likely than not due to treatment of an oval window fistula in these patients. We have also had patients in whom we do not suspect a fistula respond well to specialized tubes (see below).

We have had several patients respond positively to use of a special PE tube, designed to be heavier than normal. This dampens sound -- basically another permanent earplug. These can be removed however.

There has been a single report of treatment of hyperacusis via purposeful reduction of hearing via surgery to disrupt the ossicular chain (so-called "disarticulation"). This method of treatment would necessarily sacrifice hearing, but is potentially reversible. We think that it would be best to avoid this surgery unless symptoms are extremely severe, as in essence it involves causing deafness.

Out of the box ideas for treatment:

Domoen et al (2023) reported on a pilot study on the role of somatic modulation in hyperacusis. This include various neck maneuvers. They reported "No overall significant changes were found". They studied 18 patients in total. So from this report, it would seem that nek phyical therapy would probably not be a good treatment for hyperacusis.

What to do if you have hyperacusis ?

  1. Avoid exposure to extremely loud noises and sounds. Don't overdo it however, as keeping things very quiet may increase your sensitivity.
  2. Avoid stimulants such as caffeine, chocolate and nicotine. We also suggest avoiding ADD drugs such as amphetamines, Provigil, and medications that increase vigilance. 
  3. Avoid migraine triggers -- MSG, alcohol, aged cheese, chocolate (in other words, follow migraine diet).
  4. Exercise daily, get adequate rest, and avoid fatigue.
  5. Avoid ototoxic medications that might damage your ears such as aspirin, non-steroidals and quinine containing preparations.

Treatment of misophonia: not doing well

Smith et al (2022) reported that "Most interventions are considered inappropriate by parents of youth with misophonia and by adults with misophonia. This should be interpreted in the light of a general lack of misophonia-specific interventions. "

Research:

As of 2017, there were about 144 papers on PUBMED with hyperacusis in their title. Although there are many more with hyperacusis as a keyword, this is a relatively small amount of research effort.

References: