Klarinet Archive - Posting 000298.txt from 1998/01

From: Douglas Sears <dsears@-----.org>
Subj: Re: A440
Date: Tue, 6 Jan 1998 15:02:34 -0500

On Sun, 4 Jan 1998, J. Shouryu Nohe wrote:

> I keep seeing this 'the reed vibrates 440 times a second' stuff...and I
> have to say...huh?
>
> Are you SURE the reed vibrates 440 times when we play a concert A?

Yep.

> After
> this years Musical Physics class, I find that unlikely. The statement
> leads to a conclusion that the reed vibrates at different frequencies with
> different notes; that most certainly is not the case. The reed vibrates
> at a steady, constant frequency of something...I don't know what, but it
> remains constant. Notes change due to the length of pipe that the air
> vibratess within.

Nope. There are simple systems, used for demonstrating physical
principles, where the driving frequency is independent of the
resonant tube, but a clarinet isn't one of those. A reed has a
free-air frequency, but when it's on a clarinet, the pressure
variations in the tube make the reed flap open and closed at the
tube's frequency.

> (There's some more stuff having to do with
> wavelengths and whole odd intergers...but I already sold my book because I
> didn't like the class, and am just happy to have passed it...actually, I
> haven't checked my grades yet, so I don't know that I HAVE passed it....)

Please let us know if you passed. I would've flunked you for that.
:)

--Doug

--------------------------
Doug Sears dsears@-----.org/~dsears

   
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