Classroom Noise Meter

Privacy: what this tool does and doesn't do

The noise meter uses the Web Audio API to read amplitude — a single number per audio frame — from your microphone. The audio itself is never recorded, stored, or transmitted. There is no recording buffer, no upload, no cloud processing. Open your browser's developer tools, switch to the Network tab, and you'll see no audio data ever leaving the page.

We chose this implementation deliberately: classroom noise meters often have legitimate privacy concerns (students' voices, side conversations, IEP-related vocalisations). The right answer is to do the audio analysis on the device only, never persist it, and surface only the amplitude reading. That's what this tool does.

How to start

1. Tap "Enable microphone".Your browser asks for permission — say yes. The page reads the microphone's amplitude after that.
2. Choose a visualisation. Bouncy balls for engagement, bars for a more clinical look, color-only for the accessibility / quiet option.
3. Tune the threshold using the slider below the meter. Default 18% works for most classrooms.
4. Project it by pressing F11 for browser full-screen.
5. Turn the microphone offwhen you're done — tap "Turn off microphone" below the meter, or close the tab. The browser indicator (red dot, microphone icon) clears immediately.

Classroom routines that work with a noise meter

• Quiet-work mode— Project during silent reading, quizzes, or independent writing. The meter is the social cue; you don't need to shush. Some teachers display a smiley face when the meter stays green for the full work block.
• Volume zero / one / two — Use the threshold settings to match teacher-defined volume levels. Project zero (silent) for tests, one (whisper) for partner work, two (group discussion) for collaborative tasks. Update the threshold per activity.
• Self-monitored transitions — Show the meter during transitions between activities (e.g., putting materials away). The goal: stay green while moving. Students internalise the volume target across multiple transitions.
• Group-work check-ins — Project the meter while students work in groups — if it spikes too high, that's your cue to pause and re-set expectations rather than waiting for it to escalate.

What the three modes are for

• Bouncy balls — Engaging for elementary classes. The balls float higher when the room is louder; they fall when students quiet down. The visual reward of seeing the balls settle motivates students to lower volume.
• Bars — Cleaner, more clinical visual for middle school and up. Bars near the threshold turn red, communicating the threshold violation directly.
• Color-only— Accessibility-first option. Large green or red panel switches when the threshold is crossed, with big-text "Quiet" or "Too loud" labels. No animation — useful for students with motion sensitivity or ADHD-related visual overload.

Calibrating the threshold

Microphones differ. The default 18% threshold is a starting point — not a calibrated decibel level. Spend a minute tuning before you first project the meter for students:

1. Open the page with the room at its normal quiet-work volume.
2. The meter should stay green. If it's already too noisy, raise the threshold to about 5-10% above the current reading.
3. Try a short loud burst (clap, snap fingers near the mic). The meter should flip to red. If it doesn't, lower the threshold.
4. When students enter the room, observe their natural volume against the calibrated threshold. Adjust if needed.

If permission is denied

If a student or admin accidentally denied microphone access, the page shows a "Try again" CTA with retry instructions. To re-grant: click the lock icon in the address bar → set Microphone to Allow → reload the page → tap Enable microphone. On Chromebooks managed by a district, IT may need to allow microphone access to gotimer.org in the device policy — usually a one-line addition.