You are trying to measure the motion of the pier. Use an accelerometer, not a microphone.
--- In ap-gto@..., "N. Foldager" <nf@...> wrote:
If the Petrie dish has value, then it is far simpler to attach
a mic to
the side of a pier, and plug the mic output into your laptop audio
port.
I question the "Petri method" as I don't think it for sure can discriminate between the bell like oscillations (which we don't care about) and the bending oscillations. (Or can it? The frequency of latter should be much lower.) I believe that a microphone attached to the pier will only record the "sound of the bell", not the bending of the pier.
