Klarinet Archive - Posting 000158.txt from 1997/05

From: "Diane Karius, Ph.D." <dikarius@-----.edu>
Subj: Re: Air : amount,speed,presure etc.
Date: Tue, 6 May 1997 22:09:19 -0400

In response to a verbose statement regarding expiratory airflow
that I wrote, Jonathon Cohler wrote:
> I don't understand what you are saying here.

Sorry about that - my point was that there are times during any
exhalation that the amount of effort being exerted by the expiratory
muscles will *not* alter the airflow rate (with or without the
clarinet) and the only way to change the flow rate is to change the
airway (what you referred to as "the shape of the player's wind way
(the throat and mouth)").
Surprisingly, the more effort you exert, the more you'll have to
rely on alterations in airway (and mouthpiece) resistance to change
flow rate as the exhalation proceeds. At the extremes of effort (which
experienced clarinetists aren't going to be using too often, if at all),
only the initial flow-rate is predicted by the effort - the rest of
expiration will look the same as if you hardly exerted any effort
(and any changes will have to be produced by changing throat/mouth).
Since we don't use maximal efforts, we are able to use different muscle
efforts to vary flow rate over a wider range, but we will eventually
hit a point where our muscular effort will not change airflow.

> When I said we have no direct mechanism of controlling air speed, the
> emphasis was on the word "direct". I meant that what we can directly
> control is the pressure applied to the air stream, and this pressure is
> applied by our abdominal and other associated muscles. Because there is
> substantial back pressure from the clarinet we can blow into the clarinet
> for a LOT longer than we can blow air out of our lungs into the atmosphere
> (which is perhaps what you are talking about?).
>
> Because of the back pressure, the variations in air speed due to pressure
> changes will be relatively small, but noticeable. So we *can* change air
> speed. Just not directly. What we can change *directly* is the pressure
> applied to the column and/or the shape of the player's wind way (the
> throat and mouth), and each of these will in turn effect the speed of the
> air.
Diane R. Karius, Ph.D.
Department of Physiology
University of Health Sciences
2105 Independence Ave.
Kansas City, MO 64124
email: dikarius@-----.EDU

   
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