i think your talking about natural harmonics.
that sound can be made by doing a natural harmonic or a pinched and pushing the whammy down or really fast vibrato.
you can probally learn more about that at the whammy bar section in the topic at guitar tricks i beleive Johan and Magnus use that technique a few times.
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Jake Sommers



[This message has been edited by jake sommers (edited 04-17-2000).]