In a message dated 12/8/01 4:36:21 PM Eastern Standard Time, owner-pianotech-digest@ptg.org writes: << The movement of the soundboard that creates the compresson and refraction of air molecules is not an internal compression wave. It is the physical up-and-down movement of the soundboard panel in response to the vibrating string that does that. >>Del Some years ago Don Gibbs took a section of soundboard panel secured at the ends, and used an tone generator and a speaker to put the panel in motion. With the use of a strobe light the physical motion of the panel was easily visible. Of course it was not loaded in any fashion, but changes in frequency would change the oscillations. He stated that the test didn't really prove anything, I think we know the board is moving air, but it was quite interesting to see. Mark Ritchie
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