Misophonia
Misophonia is a disorder of decreased tolerance to specific sounds or their associated stimuli that has been characterized using different language and methodologies. Reactions to trigger sounds range from anger and annoyance to activating a fight-or-flight response. The condition is sometimes called selective sound sensitivity syndrome. Common triggers include oral sounds (e.g., loud breathing, chewing, swallowing), clicking sounds (e.g., keyboard tapping, finger tapping, windshield wipers), and sounds associated with movement (e.g., fidgeting). Oftentimes, hated sounds are repetitive in nature. Although the condition was first proposed in 2001 by Jastreboff and Jastreboff, it has yet to be considered  a diagnosable condition. Misophonia is not classified as an auditory or psychiatric condition, and so is different from phonophobia (fear of sound); there are no standard diagnostic criteria, and there is little research on how common it is or the treatment. Proponents suggest misophonia can adversely affect the ability to achieve life goals and to enjoy social situations. As of 2019 there were no evidence-based methods to manage the condition. Signs and symptoms. the literature on misophonia was limited. Some small studies show that people with misophonia generally have strong negative feelings, thoughts, and physical reactions to specific sounds , which the literature calls "trigger sounds". These sounds usually appear quiet to others, but can seem loud to the person with misophonia, as if they can't hear anything except the sound. One study found that around 80% of the sounds were related to the mouth (e.g., eating, slurping, chewing or popping gum, whispering, whistling) and around 60% were repetitive. A visual trigger may develop related to the trigger sound, and a misophonic reaction can occur in the absence of an actual sound. Reactions to triggers can range from mild (anxiety, discomfort, and/or disgust) to severe (rage, anger, hatred, panic , fear, and/or emotional distress). Reactions to the triggers can include aggression toward the origin of the sound, leaving, remaining in its presence but suffering, trying to block it or trying to mimic the sound. The first misophonic reaction may occur when a person is young, often between the ages of 9 and 13, and can originate from someone in a close relationship, or a pet. People with misophonia are aware they experience it and some consider it abnormal; the disruption it causes in their lives ranges from mild to severe. Avoidance and other behaviors can make it harder for people  with this condition to achieve their goals and enjoy interpersonal interactions. Mechanism. Misophonia's mechanism is not known, but it appears that, like hyperacusis, it may be caused by a dysfunction of the central auditory system in the brain and not of the ears. The perceived origin and context of the sound appears to be essential to trigger a reaction. A 2017 study found that the anterior insular cortex (which plays a role both in emotions like anger and in integrating outside input, such as sound, with input from organs such as the heart and lungs) causes more activity in  other parts of the brain in response to triggers, particularly in the parts responsible for long-term memories, fear, and other emotions. It also found that people with misophonia have higher amounts of myelin (a fatty substance that wraps around nerve cells in the brain to provide electrical insulation). It is not clear whether myelin is a cause or an effect of misophonia and its triggering of other brain areas. A 2021 study found that the orofacial motor cortex, a part of the brain representing lip, jaw, and mouth movement, has enhanced activation for typical trigger sounds much more than  for aversive or neutral sounds in misophonia sufferers. It also found enhanced functional connectivity between orofacial motor cortex and secondary auditory cortex during sound perception for any sound. It further reported resting state fMRI functional connectivity between orofacial motor cortex and secondary auditory and visual brain areas as well as secondary interoceptive cortex (left anterior insula). This suggests that misophonia, which is typically thought of as a disorder of sound emotion processing, is a result of overactivation of the motor mirror neuron system involved in producing the movements associated with these trigger sounds or images. Diagnosis. There are no standard  diagnostic criteria, and many doctors are unaware of this condition. Misophonia is distinguished from hyperacusis, which is not specific to a given sound and does not involve a similar strong reaction, and from phonophobia, which is a fear of loud sounds, but it may occur with either. It is not clear whether people with misophonia usually have comorbid conditions, nor whether there is a genetic component. It appears that misophonia can occur on its own or along with other health, developmental and psychiatric problems. When attempting to diagnose a patient with misophonia, doctors sometimes mistake its symptoms for an anxiety  disorder, bipolar disorder or obsessive-compulsive disorder. Classification. The diagnosis of misophonia is not recognized in the DSM-IV or the ICD-11, and it is not classified as a hearing or psychiatric disorder. It may be a form of sound–emotion synesthesia, and has parallels with some anxiety disorders. As of 2018 it was not clear whether misophonia should be classified as a symptom or as a condition. Management. As of 2018 there are no evidence-based treatments for the condition and no randomized clinical trial has been published; health care providers generally try to help people cope with misophonia  by recognizing what the person is experiencing and working on coping strategies. Some small studies have been published on the use of sound therapy similar to tinnitus retraining therapy and on cognitive behavioral therapy and particularly exposure therapy, to help people become less aware of the trigger sound. None of these approaches has been sufficiently studied to determine its effectiveness. Epidemiology. Misophonia's prevalence is not known; nor is it known whether sex, gender, or age affect the likelihood of having misophonia. The existence of several online support groups with thousands of members has been cited as possibly indicative of  its prevalence. Etymology. "Misophonia" comes from the Greek words "μίσος" (IPA: /'misɔs/), meaning "hate", and "φωνή" (IPA: /fɔˈni/), meaning "voice", loosely translating to "hate of sound", and was coined by audiologists Pawel and Margaret Jastreboff in 2000 to differentiate the condition from other forms of decreased sound tolerance such as hyperacusis (hypersensitivity to certain frequencies and volume ranges) and phonophobia (fear of sounds). Comparisons and associations with other phenomena. Some people have sought to relate misophonia to ASMR (autonomous sensory meridian response, or auto-sensory meridian response), a pleasant form of paresthesia, a tingling sensation that typically begins on the  scalp and moves down the back of the neck and upper spine. ASMR is described as the opposite of what can be observed in reactions to specific audio stimuli in misophonia. There are plentiful anecdotal reports of people who claim to have both misophonia and ASMR. Common to these reports is the experience of ASMR in response to some sounds and misophonia in response to others. Society and culture. People who experience misophonia have formed online support groups. In 2016, "Quiet Please", a documentary about misophonia, was released. In 2020, a team of misophonia researchers received the Ig Nobel Prize  in Medicine "for diagnosing a long-unrecognized medical condition: Misophonia, the distress at hearing other people make chewing sounds".