Klarinet Archive - Posting 000462.txt from 2004/10

From: orm1ondtoby@-----.net (Ormondtoby Montoya)
Subj: Re: [kl] Air flow
Date: Sat, 16 Oct 2004 00:10:17 -0400

Adam=A0Michlin wrote:

> [long snip] I am really curious to know how
> the sound generation works without the reed
> striking something [long snip]

Adam, please accept my apologies if I have misunderstood your post; but
I feel the need to 'clear the air' (if someone else hasn't already).

I don't know if you meant to imply that the reed is like a drumstick
beating rapidly against the mouthpiece and that we hear the resultant
rapid percussions as a musical tone. Probably you didn't, but I felt
the need to clear the air about this. A clarinet's sound does not come
directly from the reed hitting the mouthpiece.

Sound is a series of pressure waves. In the case of a reed instrument,
the compressions and decompressions that are the pressure waves are
caused when a valve (the reed) alternately opens somewhat to allow more
air to enter the mouthpiece and then closes somewhat to allow less air
to enter.

High speed photographs --- such as shown in the most recent issue of the
ICA magazine "Clarinet", which I haven't read yet but I've glanced at
the photographs --- show that the reed usually closes *all the way* as
the reed makes contact with the mouthpiece; but in theory, contact is
not necessary. In theory, pressure waves would result if the reed bent
enough to reduce the air flow but not enough to contact the mouthpiece,
and in theory the waves could be of sufficient amplitude to be audible.
Whether the sound would be 'good music' is another issue.

(Before high speed photography, many experts questioned whether or not
the reed closes all the way under normal conditions.)

A well-known musical physicist (Benade - not Bonade) says that the
vibrating reed also acts to a small extent as an 'air paddle' and
thereby augments the pressure waves by waving back and forth in the air.
But again, this does not require that the reed actually strike the
mouthpiece.

Thank you,
Ormond

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