Classroom Noise Meter

Uses the microphone of a computer or tablet to show a large traffic light that stays green while the classroom is quiet and turns yellow and then red as it gets louder. Use it during group work or quiet study so students can manage their own volume.

How to use

1. Press "Turn on microphone" and allow the microphone when the browser asks.
2. While the class is quiet, press "Set quiet level" and wait 3 seconds so the meter fits your room.
3. Drag the Y and R markers on the bar to set where yellow and red begin, and change the "Sensitivity" if needed.
4. Under "Display", choose "Traffic light", "Bar" or "Colour screen", and press "Full screen".

How it works

• The meter shows a relative level for this microphone and room, not decibels. Different devices give different readings in the same room.
• When red lasts longer than "Count red after" (3 seconds by default), it is counted, and with "Beep when red lasts that long" on, a beep sounds. A graph of the last 2 minutes is shown too.
• Sound is analysed on this device only. Nothing is recorded, saved or sent. Shortcuts: Space turns the microphone on or off, 1, 2 and 3 change the display, and F is full screen.

Questions and answers

Does it measure noise in decibels?

No. Microphones differ in sensitivity, so the tool only shows the level relative to your quiet room. A calibrated sound level meter is needed for real noise measurements.

The light turns red too easily. What can I do?

Drag the R marker to the right or lower the "Sensitivity". Pressing "Set quiet level" again while the class is quiet also helps.

Why does the microphone not turn on?

Check that the microphone is allowed in the site permissions of your browser. If the permission is refused, the light does not react.

Can it count how often the class got too loud?

Yes. Each time red lasts longer than the set time, the count goes up, shown as "Red for 3 s or more: 2 times". "Reset count" starts again from 0.