Classroom noise meter

"Voices down, please" stops working after the tenth time. Visible feedback doesn't. This classroom noise meter listens to the room through your microphone and shows the level on the projector: when the balls bounce over the line or the light turns red, students can see for themselves that it's time to quiet down.

It's useful for:

• Group work, where talking is fine but shouting isn't.
• Silent reading and independent work, with a low limit.
• Indoor recess and transitions, when the room gets loud fast.
• A class challenge: "If it stays green for five minutes, we play the game."

The tool gives feedback, not punishment. The "Quiet for … s" counter shows how long the class has held the level.

Pick one of three displays:

• Bouncing balls: colorful balls bounce along the bottom of the screen, and the louder the room, the higher they jump. The dashed red line is the limit: if balls keep jumping over it, the room is too loud. Younger students love it because it feels like a game.
• Traffic light: green when it's fine, amber when it's getting close (above 75% of the limit), red when it's over.
• Level bar: a horizontal bar shows the current level, with a white line at the limit. The most matter-of-fact view, good for older students.

Each display also shows a short message: "Nice and quiet!", "A bit quieter…" or "Too loud!".

The level is a 0–100 relative score, not calibrated decibels: the microphone, the room and the device all affect it. So set it once:

1. Start the meter during normal, acceptable working noise.
2. Move the limit a little above that level.
3. If the meter jumps around in a quiet room, lower the sensitivity; if it barely moves when it's loud, raise it.

The bell rings only when the volume stays over the limit for more than 1.5 seconds, so a dropped pencil case or a cough won't set it off, and there are at least 8 seconds between bells. The "Too loud: …×" counter shows how many times it has rung, and one click resets it. Your settings are saved in this browser.

A noise meter works best as a shared goal, not a warning:

• Collect green minutes. When the "Quiet for" counter reaches 5 or 10 minutes, the class earns a point. Enough points earn a reward, like a quick game at the end of class.
• Quiet station. During group work, one table is the whisper zone, with a low limit on the meter.
• Keep the balls down. With younger kids: "Can we keep the balls under the line while I hand out the papers?"
• Reflect together. At the end of class, look at how many times the bell rang and talk about what would help next time.

Match the limit to the task: higher for group work, lower for silent reading.

The noise meter uses your microphone only to measure loudness, in your browser. Sound is never recorded, saved or sent anywhere. Click Stop and the microphone turns off right away, along with the browser's mic indicator.

If the meter won't start, the message tells you why:

• Permission denied: allow the microphone from the lock or mic icon next to the address bar, then try again.
• No microphone found: connect one; a laptop's built-in mic works fine.
• Microphone busy: another app, like a video call, is using it; close it.

Press F for full screen and Esc to exit. There's no daily limit.