The project from the outer limits has come upon me. First it was a
multichannel installation with the sound circling around the speakers. I
convinced them to use 5.1 surround, which has worked out fine.
Now, they want to have two speakers playing standing waves (i.e. matched
frequencies) that cancel each other out. I understand how oppostie waves
would cancel each other out, but how does one produce matched frequencies
that would cancel each other out? Is it even possible. I'm guess that they
want two frequencies to be heard in one part of a room, and then have it not
heard in the other. Can it be done with any old sound? How would one
process a particular sound to have this effect. Is there a mathematical
formula that could be imposed in a patch?
I recall asking a friend a long time ago, that if opposite waves cancelled
each other out, then couldn't you make an electronic device that would take
sounds that were going on in an environment, and broadcast back the opposite
waveforms in real time. This was a really long time ago, when we lived next
door to a couple who were always fighting, and after fighting would blast
hip hop music that would keep going until all hours of the morning, Of
course, we laughed at the idea.
Any information would be highly appreciated.