>And there's the rub. Most people CAN distinguish between high frequency
>sines and triangles, even though the harmonics of the triangle are above
>the range of their hearing.
That's because most people who try it use a sine and triangle with
the same peak-to-peak value, which means the amplitude of the
fundamental is different. My recollection is that studies that
correct for this show that, in fact, most people ∗can't∗ hear the
difference.
> Ultrasonic components have an effect on
>perception, even if they can't be heard. Further proof of this is the
>"audio spotlight" that delivers audio using ultrasonics (see
>holosonics.com).
They use difference tones to derive audible frequencies from
ultrasonic frequencies. This doesn't prove anything about ultrasonic
perception, any more than a theremin does.
I'm open to the possibility that ultrasonic perception is real, but I
have yet to see any convincing evidence. The closest thing is the
notorious Oohashi study, which I don't find convincing, but some do.
>The question is, how high do you need to go to accurately reproduce a
>performance? Horns are the acoustic instruments that produce the most
>ultrasonics, and they don't do much past 50kHz.
Gamelans and crash cymbals go up into the MHz, IIRC.
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Tim Walters : The Doubtful Palace :
http://www.doubtfulpalace.com