Klarinet Archive - Posting 000038.txt from 1994/03

From: Cary Karp <nrm-karp@-----.SE>
Subj: Re: acoustics (was vibrato)
Date: Wed, 2 Mar 1994 22:09:11 -0500

On Sat, 12 Feb 1994, Joshua Proschan wrote:

> Cary Karp <nrm-karp@-----.SE> asks some questions
> about my description of the clarinets harmonic structure:
>
> >Could you please direct me to a source of more detailed data regarding the
> >clarinet's inharmonicity. I had always understood that the continuous
> >input of energy to the blown reed imposes a regime of harmonic
> >oscillation on the coupled reed and air column.
>
> I am not sure what you mean by "inharmonicity". What I was trying to
> describe was the departures from the simplest behavior of an ideal
> resonator, whose harmonics have frequencies that are exact integer
> multiples of the fundamental frequency. These departures will occur in
> violin strings as well as piano strings, and will occur whether the
> string is bowed, struck, or plucked. How large the departures are may
> change depending on the thickness of the string, its tension, its
> stiffness, how the sound is produced, temperature and humidity, etc.

I think you may be confusing two phenomena. It is true that the
fundamental frequencies produced by a medium as it is caused to vibrate in
its various modes do not necessarily form a harmonic series. This does not,
however, mean that the full spectrum produced by a medium in any of these
modes will be inharmonic. This factor is most certainly determined by the
mode of excitation. Media that convert continuously input energy (such
as blown winds and bowed strings) will of necessity have harmonic
spectra. Media that convert stored energy (such as plucked or
strung strings) will be nonlinear.

> Unfortunately I am short about a wall-and-a-half of bookcases, and my
> references on music and acoustics are among the victims. Benade may
> discuss this in his book on woodwind acoustics (neither the book nor
> the exact title to hand). If not, I would start with the Journal of
> Acoustics.

I'm quite familiar with this literature. You will find full support in
Benade's book on musical acoustics for my preceding argument. You will
not find that he says anything resembling a scientific explanation of
the nature of clarinet vibrato. It was the assumption that I might have
missed an important journal article that prompted my question. Further,
since Benade's book is by no means absolutely authoritative it seemed
reasonable to ask if there were any relevant unpublished experimental
results floating around.

   
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