The "Noise-o-Meter" is supposed to resemble a noise or volume level on an analog stereo system. It sits on my board, and I put a magnetic strip on the back of a red clothes pin. Before letting my students go for an activity, I move the Noise-o-Meter's hand (the red clothes pin), to the appropriate place. If the students get too loud, I adjust it accordingly.
Be careful, it it gets too loud, it might just fly off the board! :)
For more info on how this works in my classroom, please visit: