Does the size of your oral cavity change how far you pull out your tuning slide? Does having a smaller mouth size mean that you have to pull out further? I’ve explored this and similar topics here before (Part 1, Part 2). Since I’m largely self-taught with regards to physics and acoustics, I tend to defer to the experts with questions like this. Unfortunately, the experts don’t usually agree. Recently I came across a reprinted article by Thomas Moore from the March 2002 issue of the International Trumpet Guild Journal that notes the same thing.
A search of the scientific literature produced several conflicting theories on the importance of the size of the oral cavity in the production of musical sound, but very little physical evidence to support any claim. It turned out that this well-known fact was not so well known.
So Moore and his team set out to take a closer look at the oral cavity’s influence. They started out with a computer model, which indicated that the oral cavity would have no role in determining the pitch of a trumpet. But since computer models aren’t perfect they decided to use artificial lips with an artificial oral cavity designed to change size. They were able to effectively limit all other influences this way and simply measure how the size of the oral cavity would change the pitch. The result?
Our results can say nothing about the effects due to changes in air flow in the mouth and throat, which I believe to be very important. The size of the player’s oral cavity, however, is almost certainly a negligible factor in determining the pitch of any trumpet.
As interesting as it is to learn more about this, Moore offered a concluding thought about his research that has broader implications to the field of brass pedagogy and acoustical research as a whole.
. . . this situation demonstrates how even the experts can fall into the trap of accepting a believable theory as fact. It is common to find statements made by musicians or instrument manufacturers that have no basis in fact. Usually these statements are actually well informed opinions stated as fact. We should never be afraid to offer an opinion, but when discussing the science of our art I think that we should all be very careful. Maybe we should begin a lot more of our statements with the phrase “I believe…”
I believe that’s excellent advice and I think I’ll try to do that more myself.