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Investigator

Music to my ears


Who would have ever thought of my favourite bands “Feist” and one of my boyfriend’s “Mastodon” would ever be found on the same track?

Good music is a very subjective thing. Shuddering at the black metal riffs my boyfriend covets so much, this is highlighted to me on a daily basis. But one part of music which shouldn’t be up for debate is tone. Notes are laid out in military fashion, reasoned with mathematical precision and converted to exact frequencies: so how is it some people are completely tone deaf?

Those who are tone-deaf (known as congenital amusia) will be happy to hear that they share this problem with around 4% of the population. Its origin has so far not been elucidated: many believe the source of the impairment lies in genetics; others in more general anatomical abnormalities. Understanding the link between sound, processed by the primary auditory complex, and pitch, managed by the right secondary auditory cortex, is key.

According to Krista Hyde from the McConnell Brain Imaging Centre (Montreal), tone-deafness could be due to defect along a fronto-temporal auditory pathway and not to a dysfunction of the auditory cortex. This would back up previous work suggesting the auditory cortex of amusic individuals can perceive pitch correctly. Thus the source of tone-deafness lies not in the perception of the pitch but in the ability to reproduce it.

As it turns out, the ability to recognise exact frequencies and repeat them, known as “perfect pitch” (“absolute pitch” for the scientists), is a very rare ability, with than 1 in 10,000 people being graced with it. A large number of the population have what is referred to as “relative pitch”: given a reference note to start from, they can name or sing most notes.

Absolute pitch (AP) is a sought after gift – particularly for professional musicians. Being able to sight read scores makes composing and performing complex tunes a much less scary enterprise. A variety of different scientists are working to find out whether there is a pre-disposition to this ability. Overall two schools of thought emerge.

Doctor Jane Gitschier, from University of California in San Francisco, is a strong believer that the source of AP can be found in the genes of each individual. Interestingly, she found that AP is a distinct trait: people are either tone-deaf, have relative pitch or absolute pitch.

Although this seems to be true of AP, this concept does not account for the variety of tone deafness. Some people could be characterised as utterly tone-deaf – they will belt out songs totally out of tune to an aghast audience – while others, thankfully, know they cannot sing in tune: they can hear they are out of tune but cannot correct this error themselves.

A study performed by Gottfried Schlaug, from the Music and Neuroimaging Laboratory (Harvard),has found that a region of the right hemisphere of the brain, the superior arcuate fasciculus, can’t be identified in brain scans in 90% of tone deaf people.  He suggests a link between the anatomy of sound production and sound perception.

Interestingly, the studies of AP could reveal more on the matter. As Gitschier has seen in her numerous studies on people’s pitch perception abilities, AP is not an always absolute. She has reported the case of a man who was a semitone sharp for every note, but was able to hear it as such. She also reports how many AP possessors make mistakes at G sharp, in which case if they can make these mistakes, maybe the wider breadth of pitch perception in amusic people can be explained by further investigating both.

A second school of thought links AP with language, in particular tonal languages where the same word takes on a different meaning depending on how they are pronounced, as with Mandarin for example. Professor Diana Deutsch’s team from the University of Southern California has found a strong correlation between tonal languages and AP, which she believed overshadows genetics. People whose mother tongue does not use certain tones are later unable to learn to pronounce them in other languages; in the same way, it is possible that not making the brain connections linking pitch to notes at an early age makes it virtually impossible to attain them in later life.

All in all it would seem, from tone-deafness to absolute pitch, the jury is still out, and unfortunately most people will always understand sounds in the same way. But in all cases, there is a strong link between early music exposure and ability to perceive pitch: just goes to show, at a young age, all music is good for you, even the uncompromising thuds of black metal.

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Discussion

One thought on “Music to my ears

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    Posted by Sean | May 3, 2013, 6:24 am

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About me

Natacha is a research scientist and a lover of all things science! She love finding out interesting facts about all aspects of life, whether it’s how genetic engineering works or what the difference between crimped and straight hair is. There’s a bit of science behind every mystery and the Science Informant will help find the clues for everyone to enjoy and understand the amazing world of science!

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