Classroom Noise Meter

How to Use the Classroom Noise Meter

1. 1. Start listening. Press Start listening. Your browser asks whether this page may use the microphone; choose Allow. Nothing is measured until you do.
2. 2. Tune the sensitivity. With the class working at a normal level, move the sensitivity slider until the bar sits around the middle of the amber zone. Devices differ a great deal, so the first minute of set-up matters more than any default.
3. 3. Set the zones. Drag Quiet below and Too loud from to match your rules, and choose how many seconds of continuous noise should trigger the warning message.
4. 4. Put it on the projector. Full screen hides the settings and leaves the status word, the bar, the warning and the one-minute history for the class to see.

What the Bar Shows

The meter takes short blocks of sound from the microphone and works out the loudness of each as a root-mean-square value, then expresses it in decibels relative to full scale (dBFS). Zero is the loudest signal the microphone chain can carry, and everything else is negative. The bar maps a range of −70 to −10 dBFS onto 0 to 100 per cent, and the sensitivity slider shifts that range by up to 20 dB either way.

Because decibels are logarithmic, every 6 dB doubles the amplitude of the signal, so a bar that moves a little at the top of the scale represents a large change in energy. The bar rises at once and falls slowly, which makes brief spikes readable, and a thin marker holds the highest recent level for two seconds.

Relative Levels, Not Calibrated Decibels

Treat the numbers as a relative gauge, not a measurement. A true sound level in dB SPL needs a calibrated microphone, and phones, laptops and headsets differ in sensitivity, placement and built-in processing. The same classroom can read 20 points higher on one device than on another. The meter asks the browser to switch off echo cancellation, noise suppression and automatic gain control so the bar follows the room, but browsers and devices are free to ignore that request.

That is enough to run a classroom routine — the bar has been red for five seconds, time to settle — and not enough to check a standard. If you need to compare a room with a published limit, such as the background-noise criteria in the ANSI/ASA S12.60 acoustics standard for classrooms, use a calibrated sound level meter and read the standard itself.

Using It With a Class

• Agree the zones first. Tell students what green, amber and red mean for the task: silent reading, partner talk, group work.
• Set a goal for the session. The summary shows the share of time in each zone, so you can aim for a target such as more than half the lesson in green and review it afterwards.
• Use the warning as a prompt, not a punishment. A message such as Reset your voices works better than a countdown to a penalty.
• Use the history strip. The last minute of levels shows whether the noise is a spike or a steady build-up, which helps decide whether to call for attention or just wait.
• Pair it with a timer. Run it beside a countdown for a quiet-work block, then compare the sessions across the week.

Privacy and Microphone Permission

The microphone is not requested when the page loads. Only a press of Start listening asks the browser for access, and the browser shows its own indicator while the microphone is on. Audio is processed in your browser by the Web Audio API, which reads each short block, reduces it to a loudness figure and discards it. Nothing is recorded, stored, played back or uploaded, and the page keeps only the level numbers shown on screen. Press Stop listening or close the tab and the microphone is released.

If you blocked access earlier, allow the microphone in your browser's site settings and press Start listening again. Browsers only offer microphone access on secure (https) pages, and the tab needs to stay open and in the foreground for the most reliable readings.

Frequently Asked Questions

Is the classroom noise meter accurate in decibels?

No. It shows a relative level in dB relative to full scale, not sound pressure in dB SPL. Different devices read differently, so adjust the sensitivity slider until ordinary working noise sits where you want it. It is a good gauge for classroom routines and unsuitable for checking a legal or standards limit.

Does the noise meter record or send my classroom's audio?

No. The audio is analysed in your browser to get a loudness number and is then discarded. It is not recorded, stored or sent to CitationEasy or anyone else. The only data kept on the page is the series of level numbers behind the bar and the history strip, and it disappears when you close or reload the tab.

Why does my browser ask for microphone permission?

A noise meter has to listen to measure noise. The request appears only after you press Start listening, and you can refuse it. If you do, the meter simply stays idle and tells you how to allow access later.

What is a good noise level for a classroom?

It depends on the activity, which is why the zones are yours to set. Silent work needs a very low bar, group work tolerates a steady hum, and the useful rule is a clear difference between working noise and noise that stops others learning. For acoustic design targets, the ANSI/ASA S12.60 standard sets 35 dBA as the background limit for an empty classroom of ordinary size, measured with a proper meter.

The bar barely moves, or it is always red. What should I do?

Change the sensitivity. Raise it if the bar stays low while students talk, lower it if a quiet room already shows red. Moving the device nearer to or further from the class has a similar effect, and so does choosing a different microphone in your system settings.

Does it work on a phone, tablet or interactive whiteboard?

Yes, on any current browser that allows microphone access on an https page. Phone microphones are often tuned for voices at close range, so expect to adjust the sensitivity. Full screen fills the display where the browser permits it.

Will the meter keep running if I switch tabs?

Readings can slow or pause when a tab is in the background because browsers throttle hidden pages. Keep the meter in a visible window, or in full screen on the classroom display, for steady results.