From: Ronald Wong (ronwong@inreach.com)
Date: Mon Apr 22 2002 - 14:18:25 PDT
Message-Id: <l03102801b8ea2565f99c@[209.209.19.76]> Date: Mon, 22 Apr 2002 14:18:25 -0700 From: Ronald Wong <ronwong@inreach.com> Subject: re: Is it Open or is it Closed????
Neil asked:
>I play Scottish bagpipes. The bore is conical, but the double reed is played
>by air coming from the bag and is not touched by lips. Open or closed? Any
>opinion?
If I were a teacher of physics Neil, I'd probably point out that the bore
is conical and, as s result, would produce all the harmonics of the
fundamental frequency and leave it at that.
But I'm a physics teacher so I'd point out that, a conical bore is said to
behave like an open pipe and then hook up a microphone and record the whole
range of sounds produced by your bagpipes under the various conditions that
occur when a you play this instrument.
Using any of the fast Fourier analysis software programs that are out there
for physics teachers to use to compare the sound spectrum of different
musical instruments (as well as other sources of sound) - some, at one
time, were free (Vernier use to have a nice one. It wasn't free but it was
what you'd want - not surprising since he's an ex-physics teacher. I can't
believe it isn't still available in some form or another) - I'd break the
sound waves down into their component harmonics and see what is actually
produced.
I wouldn't be surprised if the students ended up with another example of
the difference between what one can expect based on general rules and what
actually can be found in the "real" world - an important lesson in my
classes. I would also have another opportunity to point out the fact that
nature can be very non-linear in its behavior at times (this also came up
in pinhole when I discussed the clarinet).
That's what I like about science teaching, you never know what is actually
going to come up when you "do the science" - and the kids are better off
for it.
ron
This archive was generated by hypermail 2.1.3 : Mon Aug 05 2002 - 09:21:41 PDT