Klarinet Archive - Posting 000133.txt from 2010/08
From: "Peter Gentry" <peter.gentry@-----.uk>
Subj: Re: [kl] About clarinet acoustics
Date: Sun, 15 Aug 2010 08:08:14 -0400
Keith you are a joint winner of the lucidity prize with Diego....
-----Original Message-----
From: Keith Bowen [mailto:keith.bowen@-----.com]
Sent: Sunday, August 15, 2010 1:03 PM
To: 'The Klarinet Mailing List'
Subject: Re: [kl] About clarinet acoustics
Peter
There is definitely a very strong coupling of the air column vibrations and
the reed vibrations, in any reed instrument (or brass instruments with the
lips for that matter). Frequencies (hence intonation) are determined
primarily by the lower modes of the air column vibrations. Whether a note
seems 'stable', i.e. playable, is governed by the design of the tube and
tone hole lattice so that the upper modes (overtones) reinforce the lower
modes or not. There are obviously less overtones available to reinforce
higher notes: frequencies above about 1500 Hz escape directly into the room
and don't contribute to the standing wave inside the instrument. Hence
higher notes are harder to play and the player has to stabilize the
frequency pretty much by embouchure control alone.
The mix of overtones of various frequencies determines the tone quality.
This mix is quite strongly affected by the reed and its interaction with the
air column.
I hope this qualitative description helps. To try to analyse tone quality in
great detail is, as you say, pretty pointless. The great makers use a deep
knowledge of acoustics as a starting point, not an end point.
Keith
-----Original Message-----
From: Peter Gentry [mailto:peter.gentry@-----.uk]
Sent: 15 August 2010 11:49
To: 'The Klarinet Mailing List'
Subject: Re: [kl] About clarinet acoustics
The acoustic properties of clarinets are indeed difficult. It is best to
stick to a simple model first to gain an understanding of the main features
of sound production. The finer points of intonation, timbre etc are more of
an art form and not susceptible to simply mathematical modelling. Most of
the great designers and manufacturers would be hard pressed to fully explain
why their solutions work.
One aspect not discussed here so far is the frequency response of the reed.
We all know that hardness and therefore stiffness affects the quality of the
sound (from squeaks to buzzes) but not much the intonation. Does this mean
that the reed is simply a means of injecting energy via pressure
fluctuations into the body of the instrument. The dynamic result depending
on the shape of the cylinder and its venting.
But it must also influence the character of the vibrations in order to
perceptibly change the timbre.
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