Loud night staff.

We have multiple complaints about night staff getting too noise at night and waking patients. One RN stated at another place she worked, they had a noice sensor that was in the shape in an ear and would light up if it got too loud. Does anyone know of this or what it is called. I have googled everything I can think of, and can't find anything? Any suggestions on how you have been able to manage noise problems on your units?
I haven't seen the ears, but we have the stoplights. Green=good, yellow=watch noise levels, red=everyone be quiet. I get the idea behind them, but we find them annoying.....mainly because the things will flash red from normal sounds like doors closing, monitors going off, etc. If you get the sensitivity right I suppose it can be a good tool.