Klarinet Archive - Posting 000086.txt from 1997/05

From: Jonathan Cohler <cohler@-----.net>
Subj: Re: Air : amount,speed,presure etc.
Date: Fri, 2 May 1997 21:16:45 -0400

Diane Karius wrote:

>Jonathan Cohler wrote (in part):
>> Furthermore, we have no direct mechanism of controlling air speed.
>True (with a partial caveat): With the exception of the earliest part of
>expiration,
>expiratory flow rate is "effort-independent" - meaning that increasing
>muscular effort will not have any effect on the flow rate. During the
>effort-independent part of expiration, the expiratory flow rate (and
>therefore flow through the clarinet) is determined by the mechanics
>of the system - airway resistance in particular (open/closed throat,
>the clarinet would be part of this, etc...). We get around this
>(here's the caveat) by exerting less than maximal muscular
>efforts (even while playing), but no matter how gently we exhale,
>we will eventually reach a point of "effort-independence".
>The stronger and faster the contraction of the expiratory muscles
>(which is certainly within our ability to control & we would think
>give us the higher flow rates) brings us to the "effort-independent"
>limit much sooner, although the initial flow rate is increased
>(this increased flow will only last for the first second or so (I'm
>making some serious assumptions about expiratory timing,
>the level of motor activation etc... - it may be much shorter
>(with higher flow rates) or a little bit longer (slower flow rates)).

I don't understand what you are saying here.

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.

------------------------
Jonathan Cohler
cohler@-----.net