Why is there no cure for the audio dropping off in Facetime?

I have been searching discussions and see no remedy for why the audio drops off in Facetime? . They can hear me but no audio to me. Is the problem Facetime? Too complex to fix? or doesn't Apple care much? I am on a 27" iMac running ML talking to a mid 2007 iMac running SL. Please advise. Thank you