quoted 8 lines 1. The experiments that "showed" that people can detect (not consciously> 1. The experiments that "showed" that people can detect (not consciously
> hear) sounds up to 100 kHz involved very high volume and transducers
> directly on the skull. In normal situations, very few people can hear
> much over 20 or maybe 23 kHz. If you could, things like ultrasonic
> motion detectors would drive people mad. Remember, the high pitched
> whine from a US TV set is only 15.75 kHz. Try playing a clean LP on a
> high-end setup and using an EQ to knock out everything below 16 kHz.
> What's left will typically have tons of phase distortion, noise, etc.quoted 5 lines 2. Ultrasonics don't influence lower, audible frequencies "by interference."> 2. Ultrasonics don't influence lower, audible frequencies "by interference."
> This is a classic rec.audio claim, and you can verify that it doesn't
> happen by feeding sine waves of appropriate frequencies through a speaker
> with a good tweeter. You won't hear a beat frequency.
>
I'm open minded about this. I suspect that if an effect does exist,
it's gonna be small, and not worth worrying about unless you're
getting into the realms of ultra-hi-fi. I accept (1) and (2), though
with the proviso that some people can apparently hear sounds well
above 20kHz.
The question is, can the presence of an inaudible unltrasonic signal
imfluence your perception of the sounds in the audio range....?
There's some experimental evidence that the brain detects the
untrasonic signal, and we don't really understand the processes
involved in the perception of sound, so it's certainly plausible....
As to whether it matters for the purposes of this discussion, probably
not, but....