audible resultant from two supersonic frequencies?

[Richard Moody]

 But the 500hz tone is easily identified, sounds like a sine wave,
and the pitch is spot on, as verified by tunelab (thanks, Bob!) on
my Pocket PC.
>
> Ric does come up with some fun questions, doesn't he?
>
> Don Mannino


Thanks Don, but damnet, can't I get two stand alone supersonic
audio generators?
>From the computer, or from Tunelab?   I love Tunelab, with its
audio output and frequency readout.   Does it go supersonic??

    On another tack, how do they make supersonic dog whistles?  Is
it that hard to get two that are 300 or 400 or 600 apart and blow
them together and listen for audible resultants??? That would
prove it once  and for all,  above all the  mumbo~jumbo
theoretical-if-ands-or-butts; or perhaps sirens as described in
Helmholtz.   ---ricrm