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Speaker 1: Welcome to brain Stuff, a production of iHeartRadio, Hey, brain

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Speaker 1: Stuff Lo and Vohla bamb Here. It's dinner time with

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Speaker 1: the family, and everyone's eating and chatting any family drama aside.

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Speaker 1: It sounds like a good time, right, But for some,

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Speaker 1: hearing other people's crunching, lip smacking, or gulping can cause

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Speaker 1: anger and anxiety. Miss Aphonia is a condition that often

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Speaker 1: evokes strong negative feelings at a person in response to

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Speaker 1: certain sounds, from other people's eating and drinking, to pen

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Speaker 1: clicking and keyboard tapping to simple breathing, so much so

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Speaker 1: that they have to get away from the source of

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Speaker 1: those sounds. But science is working on it. Back in

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Speaker 1: twenty seventeen, research published in the journal Current Biology studied

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Speaker 1: the brains of people with missophonia to see how their

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Speaker 1: brains process emotions after hearing certain sounds. Evaluated the data

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Speaker 1: of forty two participants, a twenty with missophonia and twenty

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Speaker 1: two without. People who don't have missophonia can generally tune

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Speaker 1: out everyday sounds that might be a bit bothersome. For

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Speaker 1: people with missophonia, the sensitivity comes from the pattern of

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Speaker 1: the sound, though not its volume. For the article, this

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Speaker 1: episode is based on how stuff works. Spoke with study

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Speaker 1: co author doctor Subinder Kumar, now a research assistant professor

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Speaker 1: of neurosurgery at the University of Iowa. He explained that

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Speaker 1: the aversion to certain sounds is quote a sudden realization

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Speaker 1: on the part of the person who has missophonia. They

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Speaker 1: just can't tolerate the sound and it just goes on

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Speaker 1: and on over time. While it's not known exactly how

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Speaker 1: common the condition is, it can be debilitating for the

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Speaker 1: people who do have it. On average, symptoms start around

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Speaker 1: age twelve, but they can appear as early as age five.

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Speaker 1: Trigger sounds often incite rage and anxiety. The sensitivity can

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Speaker 1: get so intense that a person might lash out verbally

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Speaker 1: in response to a sound or begin avoiding social situations

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Speaker 1: where the sound might occur, especially if they haven't been

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Speaker 1: diagnosed and have trouble explaining why they're reacting so strongly.

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Speaker 1: Imagine a person with missophonia living with a friend, but

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Speaker 1: they don't want to talk because they're bothered by the

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Speaker 1: sound of their friends breathing. Kumar said, then it gets

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Speaker 1: a little bit more complicated because they also have this

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Speaker 1: feeling that other people are not believing them so they

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Speaker 1: suffer in silence. The researchers studied measurements from functional and

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Speaker 1: structural magnetic resonance imaging, that is, fMRI and MRI, observing

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Speaker 1: parts of the brain used for processing perceptions and emotions.

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Speaker 1: They also monitored physiological data like heart rate and sweat

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Speaker 1: responses to measure participants stress levels. Participants heard three kinds

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Speaker 1: of sounds, trigger sounds like eating, breathe, or drinking, unpleasant

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Speaker 1: sounds like a baby's cry or a person's scream, and

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Speaker 1: neutral sounds like a busy cafe or the sound of rain.

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Speaker 1: Both groups were asked to rate how annoying the sounds were.

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Speaker 1: Those with mesophonia rated how much the sounds triggered mesophonic reactions.

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Speaker 1: Those without it rated how antisocial the sounds would make

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Speaker 1: them or how much they would dislike being around the noise.

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Speaker 1: The group with mesophonia did experience distress typical of their

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Speaker 1: disorder from the trigger sounds, but the unpleasant sounds didn't

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Speaker 1: produce the same response. After hearing the trigger sounds, the

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Speaker 1: group with misophonia experienced increased heart rates in sweating measured

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Speaker 1: through galvanic skin responses, but also called electrodermal activity. Basically,

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Speaker 1: when we sweat, our skin becomes more electrically conducive because

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Speaker 1: water is conducive, so you can measure even small changes

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Speaker 1: in whether or how much we're sweating by attaching electricrodes

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Speaker 1: to two fingertips and sending a tiny amount of current

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Speaker 1: through them. Increases in heart rate and sweat indicate that

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Speaker 1: we're experiencing stress. According to the authors, these responses indicate

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Speaker 1: a fight or flight response to the trigger sounds. They

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Speaker 1: wrote that people with messophonia tend quote to escape from

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Speaker 1: the environment of trigger sounds or experience anxiety and anger

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Speaker 1: if unable to escape. The group with missophonia in the

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Speaker 1: study also exhibited abnormal salience. Salience is how much we

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Speaker 1: notice something. The trigger sounds stood out more for these participants,

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Speaker 1: and the parts of their brains involved in processing salience

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Speaker 1: were more active than was observed in the other participants.

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Speaker 1: In people with missphonia, the trigger sounds activated the anterior

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Speaker 1: insular cortex of the brain, a network that directs our

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Speaker 1: attention towards stimuli that are, for whatever reason, irrelevant or

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Speaker 1: meaningful to us. Why Normally, this part of the brain

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Speaker 1: helps us say hear our name, in a noisy room

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Speaker 1: because we've learned that that's important, or it might draw

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Speaker 1: our attention to the color red or yellow for evolutionary reasons.

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Speaker 1: In the participants with missophonia, the trigger sounds also activated

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Speaker 1: parts of the brain related to processing and regulating emotion.

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Speaker 1: The researchers also asked all of the participants questions about

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Speaker 1: body consciousness based on notions of the private body, the

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Speaker 1: public body, and body competence. Kumar explained that the private

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Speaker 1: body is basically inner perception, like when a person can

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Speaker 1: easily sense their heartbeat. The public or outer body references

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Speaker 1: your consciousness about presenting yourself to and being perceived by others.

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Speaker 1: Body competence refers to how strong, fast, and coordinated you

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Speaker 1: feel like you are in comparison to other people. Both

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Speaker 1: groups had similar scores in body competence, but Kumar said

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Speaker 1: found that people with misceophonia had a higher score on

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Speaker 1: the private body and also on the public body, so

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Speaker 1: they were definitely perceiving their body internally differently compared to

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Speaker 1: people who don't have missophonia. The researcher's data can't tell

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Speaker 1: us whether this unusual self perception is a cause of

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Speaker 1: or a result of missophonia, but Kumar is optimistic that

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Speaker 1: further research can be directed to basically quiet the brain

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Speaker 1: structures related to the condition, and he hopes that in

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Speaker 1: the meanwhile, the fact that research is being done will

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Speaker 1: bring people a bit of comfort. Today's episode is based

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Speaker 1: on the article why do some people hate the sound

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Speaker 1: of chewing? Scientists might have the answer on how stuffworks

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Speaker 1: dot Com, written by Shelley Dancy. Brain Stuff is production

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Speaker 1: by Heart Radio in partnership with how stuffworks dot Com

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Speaker 1: and is produced by Tyler Klang. Four more podcasts my

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Speaker 1: listen to your favorite shows.