Imagine the sound of someone's nails scratching a blackboard.

Many people can't help but wince at the thought.

Now imagine hearing this sound again, but this time it entirely consumes you — rendering you unable to hear, think or see anything else.

It's distracting, distressing and quickly becomes unbearable. You're spurred into action: stop the sound or escape the noise.

Welcome to the world of misophonia.

Fight or flight response triggered

"Misophonia is a neuro-physiological disorder in which auditory stimuli — and sometimes visual stimuli — sets off a fight-flight reaction, which then has accompanying emotional negativity," Dr Jennifer Brout said.

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Dr Brout is a psychologist from North Carolina in the United States, who is investigating misophonia with associate professor Zach Rosenthal from Duke University.

The newly-termed syndrome, which remains largely unstudied and not well understood, sees people set off by particular sounds, which are often bodily-related or repetitive in nature.

People with misophonia can be driven to outbursts of panic, fear, disgust or rage by simply hearing others go about their day — chewing, slurping, sniffling, throat-clearing, humming, tapping and so on.

"Across the board there isn't really one specific sound," Dr Rosenthal said.

"What we see though in our patients is that there seems to be a few themes."

And while not considered a psychiatric disorder, misophonia can have very real psychiatric consequences.

"This is not something where people are simply being dramatic or erratic," Dr Rosenthal said.

"This is actual brain responses in multiple different parts of the brain that are very real and are leading to very difficult downstream effects."

Sufferers not inherently violent, hateful people

According to researchers, misophonia appears to manifest itself both physically and psychologically.

"When you see it in a child, and especially in a toddler who has very little control over their physiologic and affect regulation, you can really see what a raw physiologically and neurologically-based response this is," Dr Brout said.

"It is a response that happens in your brain and body in a millisecond ... of which you have very little cognitive control."

Our brains, Dr Rosenthal explains, are "primed to look for signals" of danger in our environment.

And interactive "defensive motivational systems" within them help us survive, by activating our flight or fight response.

"People with misophonia are having automatic responses to stimuli in their environment," Dr Rosenthal said.

"But in the moment that the stimuli are there, they can't control their instant reaction in their brain.

"It gets called anger, it gets called rage, it gets called irritation or agitation … but it's more than just simply an anger reaction."

For this reason, Dr Rosenthal says people who experience misophonia should not be characterised as violent, or full of hatred for others.

He says their response is actually not so different from the feeling of discomfort that many of us feel at the thought of nails scratching a blackboard.

"When that happens, you get the chills in your brain … you have that experience, it doesn't feel good and it passes," he said.

"Of course in misophonia, they don't get the chills response and it's not the same sounds — but it's the same principle.

"It's an instant, immediate, uncontrollable brain-driven response.

"How the person makes sense of that and how others make sense of that becomes critically important in how people cope."

Effective treatments yet to be found

With no evidenced-based treatment for misophonia, Dr Brout says people with the condition must rely on their ability to use coping skills.

"As you grow older, how you're able to cope with it really mediates how your individual response to the stimuli is going to be," she said.

"And also contextual factors — are you with a partner who is accommodating? Do you have a lifestyle in which you can avoid certain stimuli?

"It's very different for each person. And it also varies … some days are better than others."

Dr Rosenthal says in order to develop a treatment, researchers first need to figure out what the treatment is for.

"What is the 'it' that's been treated? We have to do a better job through research at understanding what that is, in order to develop evidenced-based approaches to treat it," he said.

It's hoped a multi-disciplinary approach to care, potentially including audiology, neurology, psychology, psychiatry, occupational therapy and music therapy, could yield effective treatments.

"There's a lot of … contemporary cognitive behavioural therapies that have been shown to help people tolerate and accept automatic emotional responses, physiological responses, without having to try to change them, but instead changing the way in which they relate to them," Dr Rosenthal said.

"Those are called acceptance-based approaches. There's also, of course, changed-based approaches, that directly change how we think and how our body feels.

"We think the ideal coping skills approach really attempts to use all of those tools."

A 'spectrum' of misophonia?

Dr Rosenthal says for many people, misophonia is something that is very real and very difficult.

"Yet at the same time is not clearly understood … so it's difficult to define with great specificity," he said.

As the director of Duke University's Sensory Processing and Emotion Regulation program, Dr Rosenthal says it helps to think about the syndrome on a spectrum.

"For some people, there might be no sounds in the world that lead to any irritation or annoyance," he said.

"For other people, there might be some sounds in some contexts that lead to slight irritation … all the way across the spectrum to those people who are really suffering at the very tail end of the distribution — the very extreme cases."

Dr Rosenthal says it's "quite surprising" how many people in the general population struggle with having automatic, misphonic-like reactions to certain sounds.

But that doesn't mean all of them have misophonia,

"We don't have a line of demarcation at this point that has been defined," he said.

"What we have is a syndrome that can vary in severity."

The number of studies that have been conducted into the misophonia "could be counted on one hand", so the rate of prevalence and the exact cause of the condition remain unclear.

"What we see is that kids who demonstrate auditory sensory over-responsivity earlier in life … a generally more over-responsive way of relating to sounds — those kids oftentimes are the ones who as adults we see having what sounds like misophonia," Dr Rosenthal said.

"General anxiety or general sensitivity to cues in the environment that one perceives as dangerous, that could certainly be a risk factor."

Both Dr Rosenthal and Dr Brout agree that a lot more research needs to be done to improve the understanding and treatment of misophonia.

"We simply don't know what we need to know in order to be helping our patients," Dr Rosenthal said.

"We need to look at how systems in the brain are interacting with each other in patients … we need to be doing epidemiological studies that look at the prevalence and incidence of misophonia.

"We need to look at gender differences, at course, at prognosis, at some of the risk factors for better outcomes or worse outcomes.

"These are real people … and they need help. There is a lot that needs to be done, and that's an understatement."

To hear more about misophonia, tune in to All In The Mind on RN in the coming weeks. The show airs each Sunday at 5:00pm and is repeated on Tuesday 7:30pm.