you wrote:

"Second, I don't think the ripples are a result of standing waves. I believe they occur at frequencies for which the path lengths from all of the edge sources produce reinforcement (arrive in phase) or cancellation (arrive out of phase) of the summed response from the individual pressures from each source. If a standing wave response occured, I would expect these ripples to be more like sharp tall peaks and deep narrow nulls."

Excellent observation in the last sentence. Let me think about it and see if I can desing an experiment that would confirm this.

I do trully hope that you will find a way to make your invaluable spread-sheets available without them being missused, although, sadly I have no idea how you could do that. ;-( But then again, I am not as smart as you are.;-)

M