From: Bill Shute, San Antonio College
In regards to sitcoms/variety shows shot in front of a live audience...
I have attended tapings of a number of sitcoms and a few Tonight Shows,
and my experience is that the actual response of the audience is
"sweetened" with canned laughter and that the mix is usually about
40% real and 60% canned. I have a very distinctive laugh and can
thus recognize myself on the soundtrack, and I remember jokes that
only got light laughter suddenly sounding full when the show aired,
with my guffaw surrounded by a sea of laughter that wasn't there live.
However, the "real" response was always used as a foundation for
the sweetening, much like a basic track is then added to with overdubs
in the recording industry.