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This is Part 1 of a two-part series.
Sometimes my head just spins as I try to understand misophonia. One of the most difficult areas for me has to do with the auditory neuroscience underlying the condition, since I am less familiar with it than I am with psychology. Most of us don’t know auditory neuroscience, and this inhibits our ability to read the research. I had the opportunity to interview Dr. Prashanth Prabhu, who clarified many of these issues for me. He has published over 10 misophonia papers in just the past few years. His knowledge is a goldmine, and his answers provide information that will help you read the research more easily. This post will cover auditory neuroscience, and in my next post, we will discuss Dr. Prabhu’s studies.
Jennifer Brout: Many people find it difficult to understand the difference between an auditory disorder and a neurological disorder (peripheral versus central). Would you explain this? Based on your knowledge, would you say we can rule out peripheral causes for misophonia?
Prashanth Prabhu: I usually explain it this way: The peripheral auditory system includes the outer ear, middle ear, inner ear, and auditory nerve, while the central auditory system refers to the neural pathways and brain regions that process sound after that point, including the brainstem and auditory cortex; a neurological disorder, in a broader sense, means that the nervous system is affected in its structure or function. In misophonia, the present evidence does not show clear peripheral ear damage as the main cause, and work at our lab and others has found stronger evidence for abnormal activation and connectivity in higher cortical networks rather than in the ear itself.
In our auditory brain response study, the auditory pathway up to the lower brainstem appeared intact in individuals with misophonia, and in our cochlear study, linear, non-linear, and efferent auditory measures were not significantly different from controls, suggesting that these peripheral mechanisms are not major contributors. So, I would say we cannot completely rule out every subtle peripheral influence, but the current literature supports misophonia more as a disorder of central auditory, emotional, and autonomic processing than as a primary peripheral problem.
JB: Would you explain what a central auditory processing disorder is?
PP: Central auditory processing disorder, or CAPD, refers to difficulty in the way the central auditory nervous system processes sound (beyond the auditory nerve till the auditory cortex), even when basic hearing sensitivity is normal. In simple terms, the person may hear sounds, but the brain has trouble organizing, interpreting, or making sense of them, especially in tasks involving speech in noise, dichotic listening, or temporal pattern recognition. In short, it is mainly a functional disorder, where the structure may be normal, but the processing of sound beyond the auditory nerve up to the auditory cortex is affected.
JB: Would you also explain what is meant by “higher auditory centers” in the brain?
PP: “Higher auditory centers” simply means the brain areas that understand sound, mainly the auditory cortex. These areas do more than just detect sound; they help the brain notice, process, and make sense of what is heard. So in our papers, when we say higher auditory centers may be altered, we mean the sound-processing parts of the brain may be working differently in people with misophonia
JB: There has been much debate in terms of how to categorize misophonia (neurological, neurophysiological, auditory, sensory, psychological). In your opinion, how would you categorize misophonia?
PP: In my opinion, misophonia is best categorized as a neurophysiological condition with auditory, sensory, and emotional components, rather than as a purely psychological or purely auditory/sensory disorder. I say this because our studies show altered cortical auditory processing, altered scalp topography, and poorer performance on cortical auditory processing tasks. At the same time, the findings also suggest that misophonia is not limited to sound processing alone, because emotional reactivity, attention, auditory-limbic interaction, and even multisensory mechanisms appear to be involved. So, if I had to state it simply, I would say that misophonia is a neurophysiological disorder of decreased sound tolerance with important auditory and emotional-sensory features.
JB: Anecdotally speaking, if you had to make a list of sounds typical in hyperacusis versus misophonia, what would that look like?
PP: In hyperacusis, the kinds of sounds people often mention include vacuum cleaners, barking dogs, car engines, kitchen appliances, running water, clattering dishes, babies crying, honking or traffic sounds (more in countries like India), or even loud conversation. These are usually not bothersome because of who is making them, but because the sounds themselves feel too intense.
In misophonia, the sounds more commonly described are chewing, lip smacking, swallowing, sniffing, breathing, throat clearing, tapping, pen clicking, typing, or rustling. These triggers are often human-generated and can be strongly influenced by context, including who is making the sound and the situation in which it occurs.
