Just thinking about the unnerving sound of nails on a chalkboard is enough to send shivers down your spine.
Scientists have long been puzzled as to why the screeching sound made by fingernails running down a blackboard makes us cringe.
Research has found this sound has the same frequency as a baby crying and human screaming, suggesting it is associated with survival and triggers an equivalent response.
The scratching noise invokes a physiological response, such as an increased heart rate, causing an emotional experience rather than a reflex.
Research has found this sound has the same frequency as a baby crying and human screaming, suggesting it is associated with survival and triggers an equivalent response
Most people have described nails on a chalkboard as an ‘unpleasant sensation’ and used words such as ‘shivering’ and ‘repulsion.’
A 2006 study led by Ig Nobel prize winner Dr Francis Fesmire found that sound frequencies in the middle of the audio range were most irritating and were similar to the warning cries of chimpanzees.
The researchers who conducted the work suggested that our reactions to unpleasant sounds originate in predator-avoidance instincts from our evolutionary past.
Sounds in this frequency range, 2000-5000 Hz, cause the ear canal to resonate, so the sound transmits particularly efficiently.
A separate study in 2012 found the amygdala, a roughly almond-shaped mass in the brain involved with experiencing emotions, could be why the sound hurts.
Dr Sukhbinder Kumar, of Newcastle University, said: ‘It appears there is something very primitive kicking in.
Scientists at Newcastle University discovered increased connectivity between the auditory cortex and the motor control areas related to the face, mouth and throat in those suffering from misophonia
‘It’s a possible distress signal from the amygdala to the auditory cortex.
‘There is a frequency range where our ears are the most sensitive.
‘Although there’s still much debate as to why our ears are most sensitive in this range, it does include sounds of screams which we find intrinsically unpleasant.’
However, some people have more extreme reactions to sounds, specifically loud chewing and breathing, and may have a ‘supersensitized’ brain connection.
Scientists at Newcastle University discovered increased connectivity between the auditory cortex and the motor control areas related to the face, mouth and throat in those suffering from misophonia.
Misophonia, which means ‘hatred of sound,’ is a condition in which people experience intense and involuntary reactions to certain sounds made by others, referred to as ‘trigger’ sounds.
Dr Sukhbinder Kumar, Newcastle University Research Fellow in the Biosciences Institute, said: ‘Our findings indicate that for people with misophonia, there is abnormal communication between the auditory and motor brain regions – you could describe it as a ‘supersensitized connection.’
‘This is the first time such a connection in the brain has been identified for the condition.’
