Scientists have discovered that an almond-shaped brain region is behind our aversion to high-pitched sounds, the Daily Mail reported Wednesday.
They say our reaction to the sound of scraping nails – which is in the same frequency range as screams and babies’ cries – could be an ancient survival instinct.
The study scanned the brains of 13 volunteers while they listened to a range of sounds before rating how much they liked them.
The more unpleasant a sound, the greater the amygdala – one of the first brain structures to evolve – lit up.
It then activated the auditory cortex, which processes sound, leading the volunteers to perceive the noise more keenly, according to the newspaper.
The sound of a knife on a glass bottle was rated the most unpleasant, followed by a fork on a glass. Chalk on blackboard came third.
Further analysis found that these high-pitched sounds were more easily picked up by the ear.
IANS