[Trombone-l] Acoustics of brass instruments

[Fred Hudson]

Jay makes an excellent point. In a broader sense the acoustics of brass
instruments, or for that matter wind instruments in general, are greatly
affected by the anatomy of the player. In fact, the sound issuing from a
trombone is the product of a multi-component system beginning in the
thoracic cavity of the player and ending at the bell. There have been many
threads on this list in which we have posted attempts to analyze the effects
of variation of one component without taking into account the confounding
effects of other variables. The end results of these have understandably
been non-conclusive and sometimes, unfortunately, have led to some
"intemperate" remarks. In my opinion the way to resolve this would be to
develop a mathematical model, confirmed by experiment, of the system as a
whole so that the effects of changing one component on the other components
could be predicted. But this would be a gargantuan task and almost
impossible to model the human component given the infinite variations
between us. And, after all, It is the human component that becomes the
receptor and thus the final judge of "the right sound", which is obviously
subjective and not treatable analytically.

There is enough empirical data on the mechanical components of the system to
make choices leading us to a particular sound, so when you find what works
for you, don't sweat the details - just relax, take a deep breath and blow!

my two cents worth

Fred H

"The most unsafe component of an automobile is the loose nut behind the
wheel". Your assignment, Mr. Phelps, if you choose to accept it, is to find
an analogy to playing a trombone.


----- Original Message ----- 
From: "Samuel Keyser" <keyser at MIT.EDU>
To: "Trombone-L" <trombone-l at server5.samford.edu>
Sent: Thursday, June 01, 2006 8:57 AM
Subject: [Trombone-l] Acoustics of brass instruments


> In the recent thread about how brass instruments respond to noise
> sources created at the lips, I don't recall any mention of the vocal
> tract itself.  This resonances of the vocal tract are also excited by
> noise at the source.  The process is called "coupling."  The most
> likely affect of coupling in the vocal tract is to affect amplitude
> in the horn itself as well as certain harmonics.  My guess is that
> when you hear a trombone player's sound and recognize it as Trummy
> Young, or Dorsey, or Watrous, etc. what you are in part recognizing
> is the tonal cloak that coupling lays over the resonances of the horn.
>
> I don't know if coupling has been studied in detail.  If not, it's
> probably worth it.
>
> Jay
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