Teachers have all sorts of contractions for managing noise level in the classroom. The one that comes to mind for me is the small traffic light that changes from green to yellow to red depending on noice level.
One such cloud tool that get at this same concept is Bouncy Balls. You can choose balls, bubbles, smileys, or eyeballs for your visual representation. The cloud tool uses your microphone for visual representations with the balls bouncing speed increasing depending on noise level.
One example of using this tool is having the site up on a projector during quiet reading or writing time. Students can look at the screen for visual feedback of their noise level.