On Apr 21, 1:10*pm, Helpful person wrote:
Acoustic imagery is exactly analogous to light imagery except that
having longitudinal waves there is no polarization affect.
The long wavelength makes diffraction much more dominant that for
light. *Materials also have much greater dispersion over audible
frequencies.
Lenses tend to be difficult to demonstrate compared to mirrors due to
the large impedance mismatch to air. *However, for a very limited
bandwidth an interested demonstrator could easily be made using layers
of less dense materials to build up an anti reflection coating. *This
should not be too difficult due to the long wavelengths involved.
This is a demonstration I've always wanted to make but never had the
time.
http://richardfisher.com/
Richard has it exactly. Except for polarization sound waves do
exhibit wave actions analogous to light.
I'm sorry but loud and soft is NOT analogous to large and small
images! There is such a thing as audio imaging. Go talk to any
audiophile about his stereo setup. One really nifty setup using audio
imaging is to place your speakers back from a reflective wall aimed AT
the wall. In just the same way your image appears to be behind a
mirror, the "image" speakers will appear to your ears as being BEHIND
the wall as far as the real speakers are placed a distance in front of
the wall. This is an especially nifty trick for a movie screen.
As for Peter Webb being "bugged" since sound waves "aren't used for
imaging" I'd suggest you investigate how old shipwrecks are found on
the ocean floor. Yes, sound lenses are not especially practical to
build but they DO exist. For example a balloon filled with various
gasses create them. As someone noted, acoustic lenses are sometimes
used for dispersion on horn speakers. But sound mirrors are much
easier to build so that is the typical thing.