On Sun, Feb 05, 2006 at 09:32:41PM +0200, John Anderson wrote: > On Sun, 2006-01-29 at 13:40 +0100, Wolfgang Woehl wrote: > > > 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 are called sidebands if one frequency (the 'carrier') is a radio frequency (e.g. 648 kHz - BBC world), and the other represents the information to be transmitted (e.g. audio frequencies). > They're also the reason that barbershop quartets get "ringing" chords. Could you explain what you mean by that ? -- FA
