Here is an excellent product to use in your classroom to control voice levels. Laminated and hang up on your board. You can use a clothespin to designate the voice level the students should currently be using.
Lots of people today need to really THINK before they speak. Too many people have forgotten how to be kind and speak with respect. The saddest part for me is that children are watching and learning how to imitate the same behavior.
This voice levels poster is used in most preschools during my placesment, I think it is an effective way for teachers to control the voices in the kinder. Child also remember the colors and related voice levels that they should use inside and outside.