when recording youtube there is a beat of about 2hz on louder passages. This on xp sp3 Audacity 2.0.2
That could be feedback. When you record “Stereo Mix,” everything on your computer could open up at once including speakers and microphone. Nowhere does it say that feedback has to scream like a bad club band. It can be really low, too like a thump every two seconds.
thanks Koz. Yes it does seem to have been due to audio feedback. The computer I was using is an ASUS Eee with limited freedom to control input and output. I think I solved the problem by disabling software playthrough of sound during recording. Your help is much appreciated.