Re: Ventriloquism in Birds?

["Ray Mansell" BCTess]

Bernie Krause wrote:
> This process has nothing to do with ventriloquism. Actually, both
> systems utilize two ultrasonic
> carrier frequencies transmitted by a multiple series of output
> transducers which, when combined, create
> instantaneous sum and difference signals.

Thanks for the interesting additional information, Bernie.  I was at a
lecture given by Woody Norris some years ago, and was fascinated by this
technology.  Your description explains why it hasn't become as
widespread as one might have expected, given the novelty and obvious
uses to which it might be put.

Ray