What is the most unpleasant sounds to the human ear? That, was the big scientific mystery that researchers at the Welcome Trust Center for Neuroimaging at UCL and Newcastle University in England, wished to solve. So, they recruited a group of 13 people and subjected them to 74 different noises that we encounter in our everyday lives.
In order to make the results as objective and unbiased as possible, they determined the reactions, not by the listeners' expressions but by measuring their brain activity with an MRI scanner. What they discovered was that while sounds are normally processed in the brain's auditory cortex, unpleasant sounds - identified as those with a frequency of between 2,000 and 5,000 Hz - seem to activate the amygdala neurons that aid in processing emotions, making us more sensitive to that particular noise, which is why we consider it irritating or pleasing depending on what it is.
The study which was led by Dr. Sukbiner Kuman was conducted to better understand how the human brain reacts to different sound decimals, which will in turn aid scientists to better understand medical conditions like migraines or autism, where the sufferers are very sensitive to noise.
So what are the sounds that make our hair stand? Here, are the top five as revealed by the scientists in a report published in the Journal of Science earlier this month. What will probably come as a surprise (or maybe not), is that two of them are noises most of you encounter on a regular basis.
In case you are wondering, the sound that the 13 people found most pleasant was that of bubbling water! Did you find the noises as annoying? If not, be sure to let us know what noises irritate you the most, by adding your comments below.
Resources: Telegraph.co.uk, popsci.com