the physics of whistling

[electricpete]

Most musical instruments have seemingly straightforward physical explanations. We usually change the resonant pitch by changing the length of a vibrating string or vibrating column of air. Vocal chords I think change the tension of vibrating chords.

What about whistling. It seems like the pitch is adjusted by changing the diameter of a circular opening of the lips. How does that vary the pitch?

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[electricpete]

I guess I should've checked wiki...

http://en.wikipedia.org/wiki/Whistling

It appears there is a lot more going on than just the diameter of the opening. Moving the tongue etc around within the mouth changes the resonant frequency of the mouth cavity. That makes more sense now.

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