Omni Brain

Vomiting is officially the most horrible sound ever, according to over a million votes cast worldwide in a mass online science experiment.

International visitors to the BadVibes website (www.sound101.org) -- a research project from the University of Salford -- listened to sounds such as a dentist's drill, fingernails scraping down a blackboard and aircraft flying past, before rating them in terms of their unpleasantness.

Although fingernails scraping down a blackboard is said to be the worst sound by many people, the actual recording of this sound only came 16th out of 34 sounds auditioned. Microphone feedback came a close second in the 'horribleness ranking', with many babies crying coming joint third with a horrible scraping sound.

Over 1.1m votes were statistically analysed by Professor Trevor Cox of the University's Acoustic Research Centre, who conducted the experiment in order to explore the public's perceptions of unpleasant sounds and help inform the acoustics industry.

He said: "I am driven by a scientific curiosity about why people shudder at certain sounds and not others."

I was driven by another sort of curiosity to visit the site and rate the 30 sounds myself, and find out more. Research into disgust-provoking sounds has only been conducted since the 1980s, but one of the conclusions hearkens back to music research: horrible sounds are dissonant. A clashing of pitches too close together to resonate with consonance, doesn't make beautiful music. Dissonance also explains why two or more instruments tuned differently sound horrid together.

Another finding with strong evidence is that the disgust response to cues like sounds and visceral visuals evolved as a way to avoid disease. A reason why indicators of illness like vomiting provoke strong reactions is to avoid the source, or even flee.

The recent fMRI study Dehumanizing the Lowest of the Low: Neuroimaging Responses to Extreme Out-Groups, Harris and Fiske 2006, found that images of homeless people and drug addicts provoked the strongest disgust in an array of social stereotype images, comparable to inanimate scenes of vomit and an overflowing toilet. The authors suggest there is dehumanization of these extreme out-groups based on a lack of activation in the medial prefrontal cortex, which is involved in social cognition.

A loudly vomiting homeless junkie with diarrhea would maybe be the most horrible social role? Perhaps that'll be tested in future, but in the present "...much current research is looking at how to understand the human response to sound, which means the research is more like psychology than physics."

If you want to create your own dissonant compositions there's a mixer with samples of the horrible sounds from the tests to play with.

Plus free ringtones for download. Be the most horrible cell user in the crowd with a dissonant chorus of crying babies announcing your calls. Social disgust awaits...