What is the most cringe-inducing sound of them all?

Everyone has noises that make them squirm and bury their ears beneath their hands. But which sound is the absolute worst of the worst? Researchers at Newcastle University are using fMRI technology to figure out which sounds our brains hate the most.

Researchers at the Wellcome Trust Centre for Neuroimaging at UCL and Newcastle University used functional magnetic resonance imaging (fMRI) to examine the activity of the amygdala, which processes emotional reactions, and the auditory in response to 74 different sounds. The pool of auditorily tormented volunteers wasn't very large—just 13 volunteers listened to the more and less annoying sounds—but by using fMRI technology that looks at the brain's reaction to sounds, the researchers believe they can gain greater insight into medical conditions that cause decreased sound tolerance, such as hyperacusis, misophonia, and autism.

Here were the sounds of the 74 that the volunteers found most unpleasant:

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
6. Female scream
7. Anglegrinder
8. Brakes on a cycle squealing
9. Baby crying
10. Electric drill

Sounds in the 2,000 to 5,000 Hz range were found to be the most unpleasant. These were the least unpleasant noises:

1. Applause
2. Baby laughing
3. Thunder
4. Water flowing

Photo credit: Yuri Arcurs/Shutterstock

Nasty noises: Why do we recoil at unpleasant sounds? [Newcastle University via Geekosystem]