[Trombone-l] Acoustics of brass instruments

[Samuel Keyser]

Fred has made my point much better than I have.  It is the multi- 
component aspect of the system that gives it its special character.   
Modeling it is not a trivial thing.  In terms of modeling the vocal  
tract to account for speech, for example, all kinds of things have to  
be taken into account, including sub-glottal pressure, supra-glottal  
pressure, the length of the vocal tract, the compliance of its walls,  
just to name a few.

If we don't take the whole picture into account, we are like the  
blind men touching the elephant, saying "It's a wall," "No. It's a  
tree," "No. It's a rock."

Be well everyone.

Jay

On Jun 1, 2006, at 12:41 PM, Fred Hudson wrote:

> 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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>