What is the role of the audience in a performance?

So many times
in old movies, the actors who were playing actors would complain of "a dead audience"
or they would remark, "What was with that crazy audience?"  So, realistically, there
must be a dynamic between actors and audiences. This is probably most salient with comedy.  If
the actors in a comedy, or the comic on stage do not make their audiences laugh, then the
performance is a failure, as nothing returns to the comedians, and they realize that their comic
performances are not generating the response that they should.

Essentially,
then, the audience is a receptor of the stimulating agents on stage.  Then, as part of the
dynamic between audience and those on stage, the audience also transmits energy and responses to
the actors.  Thus, a receptive audience can improve the performance of those on stage; the
responsive audience is absolutely essential to the success of those on
stage.