Interaction between auditory cortex and amygdala responsible for our response to unpleasant sounds, research finds

(Medical Xpress)—Heightened activity between the emotional and auditory parts of the brain explains why the sound of chalk on a blackboard or a knife on a bottle is so unpleasant.

In a study published today in the and funded by the Wellcome Trust, Newcastle University scientists reveal the interaction between the region of the brain that processes sound, the auditory cortex, and the , which is active in the processing of when we hear unpleasant sounds.

Brain imaging has shown that when we hear an unpleasant noise the amygdala modulates the response of the auditory cortex heightening activity and provoking our negative reaction.

"It appears there is something very primitive kicking in," says Dr Sukhbinder Kumar, the paper's author from Newcastle University. "It's a possible distress signal from the amygdala to the auditory cortex."

Researchers at the Wellcome Trust Centre for Neuroimaging at UCL and Newcastle University used functional (fMRI) to examine how the brains of 13 volunteers responded to a range of sounds. Listening to the noises inside the scanner they rated them from the most unpleasant - the sound of knife on a bottle – to pleasing - bubbling water. Researchers were then able to study the to each type of sound.

Researchers found that the activity of the amygdala and the auditory cortex varied in direct relation to the ratings of perceived unpleasantness given by the subjects. The emotional part of the brain, the amygdala, in effect takes charge and modulates the activity of the auditory part of the brain so that our perception of a highly unpleasant sound, such as a knife on a bottle, is heightened as compared to a soothing sound, such as bubbling water.

Analysis of the acoustic features of the sounds found that anything in the frequency range of around 2,000 to 5,000 Hz was found to be unpleasant. Dr Kumar explains: "This is the frequency range where our ears are 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."

Scientifically, a better understanding of the brain's reaction to noise could help our understanding of medical conditions where people have a decreased sound tolerance such as hyperacusis, misophonia (literally a "hatred of sound") and autism when there is sensitivity to noise.

Professor Tim Griffiths from Newcastle University, who led the study, says: "This work sheds new light on the interaction of the amygdala and the . This might be a new inroad into emotional disorders and disorders like tinnitus and migraine in which there seems to be heightened perception of the unpleasant aspects of sounds."

MOST UNPLEASANT SOUNDS
Rating 74 sounds, people found the most unpleasant noises to be:
1. Knife on a bottle
2. Fork on a glass
3. Chalk on a blackboard 
4. Ruler on a bottle
5. Nails on a blackboard

Related Stories

Lend me your ears -- and the world will sound very different

Jan 14, 2008

Recognising people, objects or animals by the sound they make is an important survival skill and something most of us take for granted. But very similar objects can physically make very dissimilar sounds and we are able to ...

Brain waves control the impact of noise on sleep

Sep 06, 2011

During sleep, our perception of the environment decreases. However the extent to which the human brain responds to surrounding noises during sleep remains unclear. In a study published this week in Proceedings of ...

Brain center for 'sound space' identified

Sep 19, 2007

While the visual regions of the brain have been intensively mapped, many important regions for auditory processing remain terra incognita. Now, researchers have identified the region responsible for a key auditory process—perceiving ...

Recommended for you

'Microlesions' in epilepsy discovered by novel technique

19 hours ago

Using an innovative technique combining genetic analysis and mathematical modeling with some basic sleuthing, researchers have identified previously undescribed microlesions in brain tissue from epileptic ...

Thumbs-up for mind-controlled robotic arm (w/ Video)

20 hours ago

A paralysed woman who controlled a robotic arm using just her thoughts has taken another step towards restoring her natural movements by controlling the arm with a range of complex hand movements.

The sense of smell uses fast dynamics to encode odors

23 hours ago

Neuroscientists from the John B. Pierce Laboratory and Yale School of Medicine have discovered that mice can detect minute differences in the temporal dynamics of the olfactory system, according to research ...

User comments

Adjust slider to filter visible comments by rank

Display comments: newest first

Parsec
5 / 5 (1) Oct 11, 2012
I am most sensitive to repetitive clicking noises only at certain repetition rates. In other words, a repeated click that is too slow or too fast doesn't register as unpleasant at all, while the chirping of a seat-belt not being fastened drives me up a wall.

Does that make me weird? Or are the auto manufacturers just masochistic? Maybe both?

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.