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Re: Brass instruments



I got a kick out of Jim Green's response about kissing, and also about
not wanting to play any instrument that he must put in his mouth. But
maybe that's what Jim needs to do (play the instrument... kissing is
optional).

Jim says, "in the case of the brass instruments, the excitation
produced by the flapping lips controls the frequency of the note
heard." This is partly true, but I think mostly not true. To
understand this fully you simply have to do it.

When I demonstrate the trumpet (and straight tubes, etc.) to my
students, I tell them I am trying to vibrate my lips at a particular
frequency (which I demonstrate with the mouthpiece only), then I put
the mouth piece in the trumpet or tube, and a different frequency comes
out. I explain that the trumpet simply will not allow me to vibrate my
lips at the frequency I was trying to "play." It is not as simple as
Jim's implication that the impedance matching is better for lips
vibrating for the correct frequency versus the wrong frequency. That
implies the lips are capable of vibrating with the "wrong" frequency,
but the horn does not couple this wrong vibration to the air. In
actuality the lips cannot vibrate at the wrong frequency, the
interaction between the standing wave and the lips prevents lip
vibration at any frequency other than the harmonic frequencies. For
any particular fingering there are a few harmonics the player can
choose to play via lip control, but this is a very small subset of the
frequencies at which the lips can vibrate by themselves.

Students who have played a wind instrument immediately know what I'm
talking about. Other students are clueless. To help the clueless
students I provide an inexpensive mouthpiece and a straight tube and I
make these available to them outside of class. They can come in and
play with it as a group or all by themselves. If they have aversions
to putting things to their lips, especially things other students have
put to their lips, there is a sink with antibacterial soap and they can
wash everything before trying it. Some students make use of this while
others choose to remain clueless.

Readers who are having difficulty understanding this simply have to try
it because I don't know of any other way to convince you.

Michael D. Edmiston, Ph.D. Phone/voice-mail: 419-358-3270
Professor of Chemistry & Physics FAX: 419-358-3323
Chairman, Science Department E-Mail edmiston@bluffton.edu
Bluffton College
280 West College Avenue
Bluffton, OH 45817