[linux-audio-user] Re: 192kHz

[John Anderson]

On Sun, 2006-01-29 at 13:40 +0100, Wolfgang Woehl wrote:
> fons adriaensen <fons.adriaensen at skynet.be>:
> 
> > There are certainly instruments that produce sound well
> > above 20 kHz. Now to get 'beats' between two of those
> > requires something non-linear - just summing them is not
> > enough. Our ears are non-linear at high sound levels, so
> > in a real performance this could happen. But I don't
> > think it will be noticeable at any sane sound levels.
> 
> Still don't understand the non-linear part here :/
> 
> I make 2 audio files with 400 and 500 hz sine tones and play 
> them along (out of ardour). There is clearly audible beat 
> frequency, a 100 hz hum and harmonics of that.

You should also get 900Hz. They're the sum & difference frequencies.
Apparently broadcast people called them sidebands? They're also the
reason that barbershop quartets get "ringing" chords.

I bumped into this page that explains non-linear distortion:

http://www.isvr.soton.ac.uk/SPCG/Tutorial/Tutorial/Tutorial_files/Web-hearing-difference.htm

bye
John