Biting into a crisp apple or chomping on some crunchy chips makes a very distinct sound. For some, eating noises just signal that someone is enjoying their food. For others, though, it's downright annoying and anger-inducing. Well, there's a word to go along with this rage — misophonia — and scientists have finally figured out why some people have it.
What Is Misophonia?
Misophonia is defined as a "hatred of certain sounds," which essentially means normal and everyday sounds irritate the listener. It includes chewing and eating noises and also sounds like heavy breathing and lip smacking. The term was first coined in 2001 by Margaret M. Jastreboff and Pawel J. Jastreboff of Emory University in a paper about hyperacusis — a condition where people are sensitive to certain sound frequencies.
Olana Tansley-Hancock, a 29-year-old from Kent, told BBC News she's been living with misophonia from the age of 8. For Tansley-Hancock — her trigger noises include eating, rustling sounds, and breathing — hearing certain things makes her want to lash out, as she feels a threat.
"Anyone eating crisps is always going to set me off, the rustle of the packet is enough to start a reaction," says Tansley-Hancock. "I spent a long time avoiding places like the cinema. I'd have to move carriages seven or eight times on 30-minute train journeys, and I left a job after three months as I spent more time crying and having panic attacks than working."
The Science Behind Misophonia
Why some people loathe such noises and others don't eluded scientists for some time, but now researchers from U.K.'s Newcastle University have a scientific explanation. According to the team, who published their findings in the journal Current Biology, those with misophonia have different frontal lobe activity than those without misophonia.
In the study, the researchers used a magnetic resonance imaging (MRI) machine to see the brain activity in subjects with misophonia and those without the condition while they listened to an array of noises. The sounds fell into one of three categories: neutral (rain, busy café, a kettle boiling), unpleasant (baby crying, a person screaming) and trigger (sounds of eating and breathing).
The researchers found that participants with misophonia had different brain activity that non-sufferers when "trigger" noises were played that resulted in "heightened physiological response with increased heart rate and sweating."
Specifically, there were "abnormal connections" between the frontal-lobe area and the anterior insular cortex (AIC) — located in the grey matter and involved in processing emotions. Those with misophonia had increased activity in the front-lobe area and the AIC when presented with trigger sounds, while their non-misophonic peers only saw an increase in the AIC and a decrease in the frontal region.
The Future of Misophonia
For skeptics and doubters out there, the study confirms misophonia is a real condition.
"I hope this will reassure sufferers," says Tim Griffiths, Professor of Cognitive Neurology at Newcastle University and UCL, in a press release. "I was part of the sceptical community myself until we saw patients in the clinic and understood how strikingly similar the features are."
Griffiths added: "We now have evidence to establish the basis for the disorder through the differences in brain control mechanism in misophonia. This will suggest therapeutic manipulations and encourage a search for similar mechanisms in other conditions associated with abnormal emotional reactions."
As for what's next, Dr. Sukhbinder Kumar, from the Institute of Neuroscience at Newcastle University and the Wellcome Centre for NeuroImaging at University College London, says the findings can play a role in establishing therapy.
"My hope is to identify the brain signature of the trigger sounds — those signatures can be used for treatment such as for neuro-feedback for example, where people can self-regulate their reactions by looking at what kind of brain activity is being produced," Dr. Kumar says in a release.
Read more: Misophonia: Scientists Crack Why Eating Sounds Can Make People Angry from BBC News