Author: joannew
Date: 2007-09-02 11:44
I have a couple of comments, after reading the full perfect pitch study mentioned in these news reports (available free from PNAS.org).
First, this study in no way tested a genetic basis for perfect pitch - no DNA was studied, no family groups analysed, nothing that might actually help them identify a gene for perfect pitch. This is a typical case of the headline not representing the content of the study. They only make this surmise based on a bimodal distribution (ie. you have it or you don't), rather than seeing perfect pitch as an extreme of a broad distribution. Perhaps there is some extent of genetic control, but I can imagine other mechanisms which could give the same result. Someone mentioned above a possible window of opportunity to develop this ability. Perhaps many of us are born with the capability, but without training at a specific point in our brain development, the ability is lost.
In any case, it's a very nice study. They show a systematic bias towards too-sharp identification with age, and discuss possible mechanisms, like changes in elasticity of the membrane within the cochlea, or reduction in the density of hair cells.
But what was really interesting to me was the distribution of accuracy in note naming. Almost everyone nailed the A and the D, but there were systematic errors in the 'black key' notes. They proposed a kind of magnet effect, due to heightened perception caused by tuning to A (at various pitch standards), which is quite a nice idea, but remains to be tested.
But independently of the 'A magnet', I think this tells us as much about our tuning system as about the neurobiology of pitch perception. Our standard equal tempered tuning forces our scale into even intervals, rather than optimizing the primary intervals depending on the key of the music. So the C#, D# and G# were almost always identified too sharp, very rarely too flat. But I wonder: if the test had included justified tuning scales, in which C# and Db, for example, are actually different notes, would this bias would have disappeared?
Proponents of just temperament have argued that we have done music a huge disservice by switching to equal temperament. Perhaps this is the bioloical evidence that equal temperament doesn't quite resonate with our brains.
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