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Hearing management

Updated 04 December 2017

The 10 most horrible sounds in the world

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.

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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 in the Journal of Neuroscience 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 amygdala, which is active in the processing of negative emotions 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."

How the research was done

Researchers at the Wellcome Trust Centre for Neuroimaging at UCL and Newcastle University used functional magnetic resonance imaging (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 brain response 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 auditory cortex. 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."

The 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

6. Female scream

7. Anglegrinder

8. Brakes on a cycle squealing

9. Baby crying

10. Electric drill

The least unpleasant sounds

1. Applause

2. Baby laughing

3. Thunder

4. Water flowing

What noise do you find most unpleasant? E-mail is at community@health24.com

(EurekAlert, October 2012)

Read more:
Noise levels of common sounds 

Stop that noise pollution

 

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Dr Kara Hoffman graduated from UCT in 2004, thereafter she completed her year of community service in Durban. In 2010 she completed her Masters Degree in Paediatric Aural Rehabilitation from UKZN. In 2016, she became a Doctor of Audiology through the University of Arizona (ATSU). Dr Hoffman and her partner Lauren Thompson opened a fully diagnostic audiology practice called Thompson & Hoffman Audiology Inc. In 2011 with world-class technology and equipment to be able to offer the broad public all hearing-related services including hearing testing for adults and babies, vestibular (balance) assessments and rehabilitation, industrial audiology, hearing devices, central auditory processing assessments for school-aged children, school screening, neonatal hearing screening programmes at Alberlito and Parklands Hospital, cochlear implants and other implantable devices, medicolegal assessments and advanced electroacoustic assessments of hearing. Thompson and Hoffman Audiology Inc. are based at Alberlito Hospital in Ballito, St Augustines Hospital in Durban and at 345 Essenwood Road, Musgrave. The practices are all wheelchair friendly. There are three audiologists that practice from Thompson & Hoffman – including Dr Kara Hoffman, Lauren Thompson & Minette Lister. The practice boasts professional, highly qualified, and extensive diagnostic services where all your hearing healthcare needs can be met. The additional licensing in vestibular assessment and rehabilitation, paediatric rehabilitation and cochlear implantation places this practice in one of the top specialist audiological positions in South Africa, with a wealth of experience in all clinical areas of audiology and is a very well respected and sought-after practice.

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