Zero Noise Classroom

If you want a countdown timer and noise meter for your classroom try Zero Noise Classroom as a Chrome App.

From their website, "The free noise level display and stopwatch for the cooperative classroom.

It helps students be aware of the noise level in the classroom during cooperative learning activities, and moderate it accordingly.

When time is over, the percentage of time that the noise level has exceeded the optimal level is displayed, so the teacher can use that value in gamification techniques."

To see the website, click here.