Scientists uncover the real reason why loud eaters and mouth breathers gross us out

Lip-smacking, chomping, loud eaters and noisy mouth breathers tend to gross us out. But for people with misophonia—a disorder in which tolerance of such sounds is dramatically decreased—hearing those noises can cause extreme anxiety, panic, or anger. Why the discomfort though? According to new research, some misophonia may be caused by the brain "mirroring" the activity that the person hears. Essentially, they freak out because subconsciously it's as if they are making the triggering sounds themselves. According to the director of the International Misophonia Research Network, this is the first breakthrough in the field in 25 years. From Scientific American:

The research team, led by Newcastle University neuroscientist Sukhbinder Kumar, analyzed brain activity in people with and without misophonia when they were at rest and while they listened to sounds. These included misophonia triggers (such as chewing), generally unpleasant sounds (like a crying baby), and neutral sounds. The brain's auditory cortex, which processes sound, reacted similarly in subjects with and without misophonia. But in both the resting state and listening trials, people with misophonia showed stronger connections between the auditory cortex and brain regions that control movements of the face, mouth and throat. Kumar found this connection became most active in participants with misophonia when they heard triggers specific to the condition.

"Just by listening to the sound, they activate the motor cortex more strongly. So in a way it was as if they were doing the action themselves," Kumar says. 

The Motor Basis for Misophonia (The Journal of Neuroscience)

image (cropped): Alberto Varela – (CC BY 2.0)