<HTML> <TT>Ric,</TT><TT></TT> <P><TT>The unisons can be in phase, but chances are fairly low in this experiment. Some noise reduction systems invert the phase of the  _noise_ to cancel it, the same effect you notice when the sine wave drops in intensity from beating. So there will be an overall change in the harmonic content in the combined signal of the two oscillators depending on how much their phasing differs, but unless there is a difference in frequency you probably won't notice.</TT><TT></TT> <P><TT>Clark</TT></HTML>