Chapter by Dr. Jennifer Jo-Brout (Book by Shaylynn Hayes)
The term Misophonia, which literally means “hatred of sound,” was first coined by Jastreboff and Jastreboff (2001). Jastreboff & Jastreboff (2001) coined the term misophonia as they distinguished these patients from those with hyperacusis. Hyperacusis patients aversely react to noises perceived as loud, whereas misophonics react to “repetitive or pattern based noises” regardless of decibel level (Jastreboff & Jastreboff, 2014). According to the Jastreboff’s both conditions are subsumed under “Decreased Sound Tolerance” and both conditions relate to “aberrant” associations between the auditory and the limbic system. However, in Misophonia, auditory triggers include slurping, lip smacking, breathing, and chewing versus perceived loud noises, as in hyperacusis. Because these patterned based noises are often associated with a person and/or not related to intensity, the Jastreboff’s (2014) hypothesized that in Misophonia, these aversive responses were “learned” or “cognitively mediated.” That is, in misophonia, there is a negative cognitive association that has been paired with auditory stimuli that goes beyond a “subconscious” association between the auditory cortex and limbic system (as in hyperacusis). The learned versus inborn nature of the aversive reactivity still of debate. However, newer research (along with research in similar disorders) supports as the Jastreboff’s suggested, that when a person with misophonia hears a sound that they interpret as noxious, autonomic arousal occurs and fight/flight is often activated.
To date, Misophonia has mostly garnered attention from researchers in audiology, Obsessive Compulsive and Related Disorders, Anxiety, and Synesthesia. In audiology, research both addresses similarities and distinctions between Hyperacusis and Misophonia. In psychology, commonalities between Obsessive Compulsive and Related Disorders and anxiety are currently being investigated. In neuroscience, models of misophonia as a form of synesthesia are proposed. Across this research is also discussion of “general sensory sensitivities,” “sensory-defensiveness” and “multisensory processing” (e.g. Wu, Lewin, Murphy, & Storch, 2014).
In regard to Sensory-Defensiveness it is also important to note that there is a remarkable overlap in Misophonia symptoms and Sensory Over-Responsivity (SOR), a subtype of Sensory Processing Disorder (SPD). Notably, the research in SOR has been related mainly to children, although currently it addressing adults. While SOR research concerns a variety of sensory stimuli, it is important to note that within these groups were children known as mainly “auditory over-responsive.” There are numerous papers that separate out auditory over-responsive symptoms, as well as studies focused specifically on auditory gating (e.g. Gavin, W. J., Dotseth, A., Roush, K. K., Smith, C. A., Spain, H. D., & Davies, P. L., 2011). SPD/SOR research, even that which was specific to the auditory modality, did not differentiate between loud and repetitive sounds. This makes it difficult to extrapolate from SOR to Misophonia. However, the overlap in behavioral symptoms in regard to “auditory over-responsivity” is remarkable.
The research in Misophonia is in its infancy. However, reviewing bodies of research across disciplines such as audiology, occupational therapy, neuroscience and psychology will add to the basis for an understanding of this condition, and can inform the next steps for research. This is of great importance, as those who suffer with Misophonia report levels of impaired functioning ranging from moderate to severe across multiple life areas. Some sufferers even report withdrawal from numerous activities and social isolation as a result of the disorder.
The full book can be found here: http://www.amazon.ca/Full-Sound-Fury-Suffering-Misophonia/dp/1517018706/ref=tmm_pap_title_0?ie=UTF8&qid=1452487109&sr=1-1