Chewing or breathing sounds make you seethe? Blame your brain | Science News for Students

Chewing or breathing sounds make you seethe? Blame your brain

For people with misophonia, some sounds that most people ignore can trigger intensely negative responses
Feb 22, 2017 — 7:10 am EST
kid eating corn

Some people find everyday sounds such as eating, drinking and breathing intensely annoying. People with this condition, called misophonia, have structural and functional differences in their brains, new data show.

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For many people, the sounds of slurping coffee or crunching on an apple can be mildly annoying. But it can leave others seething. And their rage is very real, a new study finds. Certain sounds — especially eating, drinking and breathing — can boost activity in parts of the brain that deal with emotions. This can turn on a strong emotional reaction, leading to anger or anxiety.

For such people, the brain gives extra importance to certain sounds, says Sukhbinder Kumar. He’s a cognitive neuroscientist in England at Newcastle University's medical school.  What is not clear, he adds, is why only certain sounds trigger this reaction.

His team described its new findings February 2 in Current Biology.

This intense sensitivity to some sounds is called misophonia (Mees-oh-FOH-nee-uh). The term means “hatred of sound.” Researchers aren’t sure how common the condition is. One study of college students, however, found that it afflicted nearly one in every five people tested.

Many people view those with misophonia as being just too sensitive to sounds, notes Jennifer Jo Brout. A psychologist at Duke University Medical Center in Durham, N.C., she was not involved with the  study. In fact, she says, the new work “really confirms that it’s neurologically based,” says Brout. By that she means that it is caused by certain physical structures or activities in the brain.

In the new study, researchers had 42 volunteers listen to various sounds while inside a brain scanner. This device let researchers view the activity in different brain areas. Twenty volunteers had misophonia; 22 didn’t.

Somesounds the recruits heard were neutral, such as rainfall. Others, such as a wailing baby, tend to annoy most people. A third set were chosen because they were known to especially bug people with misophonia. These included the sounds of chewing and breathing.

Both groups of people reacted similarly to the neutral and annoying sounds. But only the misophonics responded dramatically to chewing and breathing sounds. Their brain scans also showed a boost of activity after such sounds in an area known as the anterior insular cortex. This structure plays a role in processing emotions. Kumar’s group also found more connections among regions that help with processing emotions.

What's more, people with misophonia showed an increased heart rate. Their skin was more electrically conductive, too. Such skin conductivity tends to rise when emotions are high. It’s part of the same sort of fight-or-flight response that gets triggered when facing a wild animal or speaking in public. And those, of course, are also very stressful situations.

Power Words

(for more about Power Words, click here)

anterior    An adjective meaning near the front of some structure, or it can mean earlier tin time.

biology     The study of living things. The scientists who study them are known as biologists.

brain scan     The use of an imaging technology, typically using X rays or a magnetic resonance imaging (or MRI) machine, to view structures inside the brain. With MRI technology — especially the type known as functional MRI (or fMRI) — the activity of different brain regions can be viewed during an event, such as viewing pictures, computing sums or listening to music.

cognitive     A term that relates to mental activities, such as thinking, learning, remembering and solving puzzles.

conductive     Able to carry an electric current.

cortex     The outermost layer of neural tissue of the brain.

fight or flight response    The body’s response to a threat, either real or imagined. During the fight-or-flight response, digestion shuts down as the body prepares to deal with the threat (fight) or to run away from it (flight).

heart rate     Heart beat; the number of times per minute that the heart — a pump — contracts, moving blood throughout the body.

insular cortex   (also known as insula) This is a part of the cerebral cortex — the outermost layer of brain tissue in people. Instead of being on the outside of the brain, though, the insular cortex is part of a deep fold on either side of the brain, right above the ears. The insula plays a role in consciousness — awareness of ourselves and the world around us. The front part of the insula — called the anterior insula — helps us process our own emotions, feel disgust and empathize with other people’s feelings.  The insula is also involved in movement, drug addiction, swallowing and even controlling heart rate and blood pressure.

misophonia    Meaning "hatred of sound," it's a condition affecting some people that causes them to become highly anxious or annoyed by certain sounds, especially the sounds of eating, drinking or breathing.

neurological     An adjective that refers to the brain, spinal cord or nerves. Doctors who study these tissues and cells are known as neurologists.

physical     (adj.) A term for things that exist in the real world, as opposed to in memories or the imagination. It can also refer to properties of materials that are due to their size and non-chemical interactions (such as when one block slams with force into another).

psychologist     A scientist or mental-health professional who studies the human mind, especially in relation to actions and behavior. 

Citation

Journal: S. Kumar et al. The brain basis for misophonia. Current Biology. Published online February 2, 2017. doi: 10.1016/j.cub.2016.12.048.

Journal: M.S. Wu et al. Misophonia: incidence, phenomenology, and clinical correlates in an undergraduate student sample. Journal of Clinical Psychology. Vol. 70, October 2014, p. 994. doi: 10.1002/jclp.22098.