fons adriaensen <fons.adriaensen@xxxxxxxxx>: > 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. Checked with jaaa: Adding a 99 hz tone to the mix results in another 1 hz beat frequency. Found http://hyperphysics.phy-astr.gsu.edu/hbase/sound/beat.html and there seems to be no reference to non-linearities that would be crucial for the phenomenon to come up. I seem to be missing something obvious and maybe you can throw another much appreciated explanation at me? -- Wolfgang
