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Doublereed Archive - Posting 000061.txt from 2004/10
From: PhilFrei@-----.com
Subj: [DR-L] Another reed-physics conjecture
Date: Wed, 13 Oct 2004 15:43:32 -0400
Hi -
(I'm mostly talking about oboe reeds, but the principle should also apply to
bassoon reeds.)
I've been puzzling over an aspect about embouchure control of the reed. It
seems there may be situations where it is quite desireable to use an asymmetric
(top vs. bottom) amount of pressure on the blades. I've seen it described at
least three ways.
1) (Lower lip) In a recent master class at SF Conservatory of Music, Ray
Still described using pressure on the second octave key to help nudge the reed a
little deeper into the cushion of the lower lip. The effect seemed to add
support and improve the tone (make is less bright) on just those high register
notes that tend to need this the most.
2) (Upper lip) In another SF Conservatory master clase, Elaine Douvas
described a technique for helping low notes come out. If I have this right, she would
put some slight pressure with her thumb to press the reed into her upper lip
on the upper note, then release this pressure for the lower note. There were
important aspects of breath control and direction that were included in her
description of the technique, but it's the fact of the asymmetric pressure on the
blades that concerns me here.
3) Bill Bennett teaches a posture of "head up, oboe close to the chest". This
puts the reed at a rather sharp angle in the mouth. The pressure on each
blade may indeed be even, and he emphasizes playing on the tip, but this angle, it
would seem to me, would create asymmetries perhaps due to the placement of
the lips (the lower lip probably being lower down the reed than the upper, even
with the emphasis on staying at the tip).
Relooking at "The Art of Oboe Playing" by Sprenkle and Ledet, I notice there
are references to cushioning the reed in the lower lip, but it is unclear if
the intended result is a difference in pressure between the two lips. The
authors don't make reference to the hand pressure needed to make this happen.
Though sometimes things like that are more or less an unconscious part of "getting
it" than explicitly laid out.
Here is my conjecture.
I think that there are two main ways an embouchure can affect the tone. One
is by dampening vibrations at a position on the reed. Brighter vibrations
(higher in the overtone series) tend to predominate at the tip, and lower harmonics
at the back of the reed. Thus placing the lips at the tip tends to cover the
highs more than the lows, and placing the lips at the back end tends to leave
the brighter vibrations free.
But another aspect of tone perhaps comes from the manner in which the reed
opens and shuts. I recently read that the tone is produced when the reed blades
actually start a cycle where they momentarily close entirely, and that the
bulk of time (in terms of the blade motion) is spent at either a position where
the reed is closed or where it is all the way open. (Source: Fletcher, Physics
of Music.)
Fletcher doesn't go into this, but the more abrupt of the blade motion from
open to shut and vice versa, the brighter the tone. If there was a way to
increase the amount of time spent in transition, the bursts of air going through
the reed would be a little less bursty, so to speak, and thus have fewer high
harmonics.
Perhaps the asymmetric embouchure effects the amount of time it takes the
blades to move from open to shut and vice versa. With an even embouchure, the
distance from the open to the shut position would be the same for both blades.
With an asymmetric embouchure, one blade would be slightly closer and the other
slightly more open. The "more open" blade would take longer to close or open
because of the greater distance. This slight extra time maybe makes the air
bursts a little less abrupt and thus the tone a little less bright/shrill.
So, maybe the technique allows one to add a little support without
sacrificing as much tone. In the case of the Douvas technique, the extra embouchure
support allows at least one blade of the reed a little extra freedom of movement
and the breath to be closer to a lower pressure required for the lower note.
Maybe. I'm not sure if I understand it exactly right or which, if either factor
is the one that helps with getting the low note out cleanly. She does speak a
lot about the direction and speed of the air.
Perhaps Bill Bennett's technique allows him to take advantage of this tonal
enhancement over the full range of the oboe without requiring any perterbations
of hand pressure (and the possible deleterious effects on fingering). Though,
I am reluctant to give up the "sweet spot" I've found where the tone seems to
ring the most (when the reed is at it's most perpendicular position relative
to the lips).
Any thoughts on all of this? My apologies in advance if I have
mis-represented any of the cited oboists. I am doing my best to understand.
Phil Freihofner
Albany, CA
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