Idea: The ultimate CD/DVD auditing tool

[Major Variola (ret)]

At 02:55 PM 7/8/03 -0400, Billy wrote:
>On Tue, Jul 08, 2003 at 01:26:46PM -0400, Trei, Peter wrote:
>> While the ear can't hear above 22KHz, signal above that *can*
>> effect the perceived sound, by heterodyne effects. For example,
>> if you play a single tone of 28KHz, or a single tone of 30 KHz,
>> you can't hear them.  Play them together, however, and you
>> *can* hear a beat frequency of 2KHz.
>
>Bullshit detector buzzing.
>Is this *really* true?  Have you tried it?

I haven't, but it does ring true.  You'd get 2 Khz as well as other
intermodulation products.  Standard EE stuff.

You've read about the company trying to sell highly localized
speakers?  They modulate two intense ultrasound beams, and the
air does the nonlinear mixing where they meet.

In the audiophile, lower-intensity case,
the ears' nonlinearity would do it.  Interesting info, Peter.