WASHINGTON - Do you ever shudder when you hear certain sounds, such as rustling of some type of plastic bags or a fork scraping on the bottom of a porcelain plate? Or get a tingling in your teeth when somone scrapes their fingernails on a blackboard?
It may be a mild annoyance for most, but a serious problem for people with "misophonia," from the Greek words meaning hatred of sound.
No matter how tolerant we are, most of us feel uncomfortable if a person sitting close to us in a quiet cinema starts noisily opening a bag of chips and loudly eating them.
But for some people, who suffer from misophonia, certain repetitive noise can be hardly bearable.
"Mainly sounds made by people's mouth or breathing. This is certain speech sounds, chewing, certain other sort of noisy wet noises from the mouth, noisy breathing as well. Other ones include things like repetitive noises, pen clicking, foot tapping, keyboards sometimes, packets rustling," Will Sedley of New Castle University said.
Scientists at the Newcastle University wanted to see whether there is a physical evidence of this sensitivity.
Volunteers were asked to rate the level of unpleasantness of different sounds from neutral, such as rainfall or the sound of boiling water, to irritating, like noisy eating, loud breathing or a baby crying.
Their brain scans showed that misophonia has to do with the size of an area in our brains that regulates emotional responses.
"It was smaller and less developed in people with misophonia at a group level. Nothing you'd see on an individual brain screen basis, but suggesting that there may actually be brain structural alterations," Sedley said.
But the discovery opened new questions.
"It's difficult to know which is the chicken and which is the egg, whether this is the cause of misophonia or in part, or whether this is the consequence of having this condition or an unpleasant adversant condition like this and how it affects the brain in the long term," he said.
Scientists say they also want to find out whether severe misophonia is treatable, but they say everybody should be aware that some people are genuinely sensitive to certain noises.