About and contact

Why it exists

Teachers put noise meters on the projector because a visual cue works better than repeating “voices down”. Most online meters either show a decibel number kids can’t read, or react the same way in every room, so a quiet library corner and a busy gym look equally loud. This one is built around the room you are actually in, and around what the back row can read: a state word and a colour.

The class tools (seating chart, name picker, group generator) came from the same classrooms: once a teacher has a class list, the same list should seat, pick and group the class without typing it again.

How the meter measures a room

When you press Start, the browser asks for the microphone. Ten quiet seconds set your room’s floor (a low percentile, so one cough doesn’t count). Every scene places its Noisy and Too loud lines a fixed number of decibels above that floor, which is why it behaves the same on a Chromebook in a small room and on a webcam microphone in the gym.

We ask the browser to turn off automatic volume leveling, noise suppression and echo cancellation, because those features flatten a loud room. Sound is turned into one loudness number about twenty times a second, in your browser, and the audio is thrown away. Nothing is recorded or uploaded. The privacy policy has the details.

What it is not

It is a classroom management tool, not a certified sound level meter. Browser microphones aren’t calibrated, so two laptops can read the same room several decibels apart. If you need numbers that match a real meter, use a phone sound meter once and enter the reading under Settings; the page then shows approximate decibels.

How we check it

• Every page is checked with automated accessibility tests and keyboard use, in light and dark themes.
• Pages are built to load fast on school Chromebooks and to work offline once installed.
• The free tools keep student names on the teacher’s computer only; nothing about a class reaches our servers.

If the meter behaves strangely in your room, on your device or behind your school’s filters, we want to hear about it. Real classrooms are how the scene presets get better.

Who makes it

Classroom Noise Meter is made and run independently, not by a school district or an ed-tech company. Pro subscriptions pay for the servers and the time; we don’t sell data, and student information is never used for anything but the tools you use it in.

Contact

Write to hello@classroomnoisemeter.org. Useful things to include: the page you were on, your device and browser, and what you expected to happen. We read every message. Please don’t send student names or photos.

Free, and how it stays free

The meter, the class tools, today’s Quiet jar and the lesson report are free with no account. Pro, $36 a year, adds classes synced across computers, a Quiet jar per class, and weekly and term reports. Payments are handled by Stripe; we never see your card.