Wednesday, October 6, 1999 Published at 18:35 GMT 19:35 UK
Latex lips blow own trumpet
The instrument plugs into the black ring and then the music begins
A pair of artificial latex lips puffing on a trombone is helping to reveal the mysteries of how musicians play brass instruments.
"You'd be surprised how little is known about the relationship between what a brass player does with their lips, what the instrument tries to do and the note that actually comes out," he said.
But the relationship between the shape of the lips and the note produced by the instrument is complex. Changes in lip vibration do not produce proportional changes in the note. "It's strongly non-linear," said Dr Campbell, whose work is published in New Scientist magazine.
The problem is that analysing how the lips and instrument interact requires lips to be held in a fixed position for up to 10 minutes. No human player can maintain this, which is where the artificial lips come in.
These were created by French physicists Joël Gilbert and Jean-François Petiot using two thin latex tubes. The tubes are filled with water so they mimic the density and flexibility of our own lips.
And as air is blown through them, it flows through a perforated plastic plate that simulates the effect of teeth. The tension in the "lips" can also be adjusted to mimic different playing styles.
Dr Campbell has constructed a new version of the French system in Edinburgh for a series of tests.
He told BBC News Online: "There is one very interesting feature which is not yet fully understood called "lipping". Just by adjusting the way that you set your lips on a trumpet's mouthpiece, as well as the tension of the lips and the way you blow, you can change the note quite a lot.
"A good player can change it by several tones but exactly what the player is doing is not clear. Some people think its down to the tension of the lips, others think it's the shape of your mouth and the position of your tongue and that's just the kind of thing we are researching."