Re: Making pure white light without incandescence -- is it possible?

In <5369e526-602e-41e7-88c5-f5347e3b0698@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
redbelly wrote:

On Apr 20, 8:03 pm, dkco...@xxxxxxxxx (David Combs) wrote:
Might this have some relevance?:

We all read about these experiments with human hearing.

Suppose it's proven that someone's ears can't respond to
anything above eg 15k, and that's proven by nerve measurements,
pet-scans, etc.

Yet, some such (all such?) people will say that music
or whatever cut-off at 15k sounds different, somehow (maybe
they can't say in what manner different) with same music
cut off at eg 20k.

a) what's that about?, and

I've heard that sound propagation involves nonlinear processes.
Perhaps these are converting some of the >15kHz spectrum into the
audible range.

I can say that a lowpass filter whose cutoff frequency is at or just
past the high frequency limit of a human's hearing has an audible effect
because such a filter has some atenuation at frequencies below the cutoff
frequency.

I heard all too many people say that music has significant content at 30
Hz or 32 Hz and that their loudspeakers respond significantly to
frequencies that low because moving the 32 Hz control of a graphic
equalizer has an audible effect. But even on a 1/3 octave equalizer, the
32 Hz control has some significant effect as high as 45 Hz.

- Don Klipstein (don@xxxxxxxxx)
.