On Wed, 24 Oct 2012 13:44:52 -0700 (PDT), Andy Dingley
wrote:

For acoustics, a sensibly sized gadget is going to be (acoustically) small, relative to wavelength.

May I respectfully suggest:

http://en.wikipedia.org/wiki/File:Wartuba.jpg


Oh, sorry missed the "sensibly"...


Thomas Prufer