Keeping students from talking in rehearsals

I liked reading these ideas for minimizing talking during rehearsals.  I especially like these:

Have a "sh sh sh" sound that the students join in with the teacher whenever the teacher does it.
If someone is talking, have everyone breathe in for 5 seconds, hold it for 5 seconds and breathe out for 5 seconds.
If someone is talking, teacher has the whole class stand up or sit up on edge of chair.  When talking stops, the teacher says "sit down" or "sit back."
Have them get used to silence.  When they are quiet and ready to sing, wait for a few beats of silence before conducting them to sing.
Teacher sings "oo" on a reasonable pitch and every student joins in unison.  After everyone is joined in, teacher cuts off and continues with rehearsal.

Minimize Talking