Re: Sodaplay: Tacoma Narrows resonator

[Leigh Palmer <palmer@SFU.CA>]

At 12:58 PM -0500 12/8/00, Michael Edmiston wrote (regarding types of
resonances):

> Type-2.  (C) I strike a tuning fork with a rubber mallet and note that the
> fork vibrates at particular frequencies.  (D) I bow a violin string and note
> the string vibrates with particular frequencies.  (E) I blow across the top
> of a soda-pop bottle and note that I produce particular frequencies of
> sound.

Cases (D) and (E) are examples of *oscillators*, systems that vibrate
in their normal mode(s) by means of feedback. The Tacoma Narrows Bridge
is also an oscillator. Case (C) is an example of damped simple harmonic
motion in the normal mode(s) of the system. An interesting result can
be heard if one uses a wooden mallet or a hard plastic one instead of
a rubber mallet. The same is true when one plucks a violin string at
different distances from the bridge, or with different plectra, say the
pad of a fingertip or a hard plastic guitar pick.

But I digress...

Leigh

I modified a stubby beer bottle so that I can get four distinct modes
going (separately). It takes a practiced embouchure to do this, and a
sharply chamfered lip ground on the bottle.