Classroom noise meter
Green is fine, yellow is getting loud, red is too loud — on the big screen.
– dB(A)Too loud above (dB): 65 dB(A)
Browser microphones aren’t calibrated: the reading is an estimate.
Nothing leaves your device
This tool runs entirely in your browser. What you type, play or record here stays on your device: nothing is uploaded or saved on a server.
How it works
- Press Start and allow the microphone of the computer connected to the projector or board.
- Set the limit: the face turns yellow 10 dB below it and red above it. 60–65 dB suits quiet work, 70 group work.
- Press Full screen (or F). Red appears only after a second and a half above the limit, so one dropped book doesn’t count.
Frequently asked questions
- What limit should I set?
- Start at 65 dB for quiet work and 70–75 for group work, then adjust after a few minutes watching the reading: the room, the microphone and the class all differ.
- Why doesn’t it turn red straight away?
- It uses a slow response and waits 1.5 seconds above the limit before turning red, and 1.5 seconds under it before going back — so the light follows the class, not a single bang.
- Does it work without colour?
- Yes. The face changes shape and words too — a smile when quiet, a straight mouth when loud, a stop sign when too loud — for colour-blind pupils.
- Can I use a phone?
- Yes, but a laptop near the centre of the room measures the class better than a phone on the teacher’s desk.
- Is the class recorded?
- No. It runs in your browser; nothing is recorded or sent anywhere.