Re:ears

["Michael P. Hughes, Ph.D." <pycraft@elec.gla.ac.uk>]

At 10:49 AM 3/10/98 -0800, you wrote:
>>To add fuel about sounds and feels of sound, I read somewhere a great
>>history for those who think that beyond 20 Khz (at best) there is no
>>reason to possibly ear anything.
>
>I think it's actually Mr. Neve who talks about this. I think the deal is
>that you can't hear a continuous tone over 20KHz (lower if you've abused
>your ears like me....)  but you can discern transients that have higher
>frequencies. I think Neve would demonstrate this by switching a 15KHz sine
>wave and a 15KHz square wave. All the frequencies that make it a square
>wave are above the human range of hearing, so it should sound the same as
>the sine wave, but supposedly it doesn't.

Do the higuer harmonics on a square wave count as transients?

>well, that's another thing with poor quality digital gear. If the audio
>input is not filtered right  and you put higher frequencies into it, they
>will alias into the audio. Basically they mirror around the 1/2sample rate
>frequency. It's sort of a cool affect, but a terrible thing to do to 
>music.
>If the aliasing frequencies are low in the first place, the result will be
>subtle and give you that uncomfortable feeling.

I was just thinking that - the ear supposedly picks up sound by registering
the beats along the ear cana via the little hairs.  Could it be that stuff
at 56kHz is being aliased to a lower frequency in the ear?  Or that there
is a standing wave resonance within the ear at that frequency?  Or that the
hair resonate at that frequency?

Michael