Lorin David Schultz wrote:
"Steve" wrote:

I knew a guy who found 40kHz unbearable.
We were working on an ultrasonic movement detector.
He would complain of pain and pressure in his ears any time it was
on.

I call bull**** on him.

I used to experience discomfort from ultrasonic systems too (when I was
in my early twenties... I don't have that problem anymore), but 40K?
C'mon...

I can believe the waveform coming out of those things might be pretty
crappy, and there may well be a considerable amount of sub-20K trash
coming out of them too, as well as the 40K stuff that's supposed to
be there.

I knew someone who swore he could hear C-band microwaves. Turned out
that he could actually tell when the beam was turned on and when it
wasn't. Then he found out that what he was hearing was actually
the sound of his skull expanding due to local tissue heating from the
beam. This would have been about 2,000 KW ERP, I think, but at a good
distance.
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."