How to use it
- Press Start mic test and allow microphone access when the browser asks.
- Speak normally. The bar and the peak and RMS numbers move with your voice; the line under them says whether sound is arriving, whether it is very quiet, or whether it is clipping.
- If you have more than one microphone, pick it from the list. Record 10 seconds to hear yourself as others hear you, and save the clip if you want it.
- To hear the raw microphone, switch off the browser’s echo cancellation, noise suppression and gain control.
Reading the meter
Levels are in dBFS, decibels below full scale: 0 dBFS is the largest value a digital recording can hold, so every real reading is negative. Peak is the loudest single sample in the last fraction of a second; RMS is the average power, which tracks how loud the sound seems. For a pure tone the RMS sits 3.01 dB below the peak; speech usually has a much bigger gap because it is spiky. Clipping means samples reached full scale (we flag any sample at 99.9% of it): the tops of the waveform are cut off and the sound distorts, so lower the input level or move back. A good level keeps your loudest moments clearly below 0 dBFS and your normal speech well above the reading you get when you stay silent, which is the room’s noise floor.
What the browser does to your microphone
For calls, browsers turn on echo cancellation, noise suppression and automatic gain control by default, and they change what you hear. We fed Chromium a steady 440 Hz tone at −20 dBFS through a virtual microphone. With all three switched off the page measured -20.0 dBFS peak and -23.0 dBFS RMS, the exact values. With the defaults on, the same tone measured -42.5 dBFS RMS. Turning the switches on one at a time showed where the drop came from: noise suppression alone gave -42.5 dBFS, echo cancellation alone -23.4 dBFS and gain control alone -23.0 dBFS. A steady tone looks like background noise, so noise suppression removes most of it. If a music instrument, a test tone or a quiet voice sounds weak in a web app, this is a likely reason; the switches here show the difference on your own microphone. The track also reports which processing the browser actually applied, shown under the switches.
If it does not work
- Access blocked: allow the microphone from the icon in the address bar or the site settings, then press Start again. On a Mac, apps also need permission in System Settings › Privacy & Security › Microphone; on Windows, in Settings › Privacy & security › Microphone.
- No sound arriving: check the right device is selected here and in your system sound settings, and that a hardware mute switch or headset mute is off.
- Device busy: another app (a call, a recorder) may be holding the microphone. Close it and try again.
What we tested
On October 15, 2026, in Chromium with a virtual microphone playing test files: a 1 kHz tone at −6 dBFS read -6.0 peak and -9.0 RMS, a 440 Hz tone at −20 dBFS read -20.0 and -23.0, a full-scale square wave read 0.0 and 0.0 with the clipping light on, and silence read minus infinity with the “no sound” message. The 10-second recording decoded as 9.96 seconds of audio. A blocked permission shows the instructions above, and the page fits a 390 px screen.
Sources
- W3C, Media Capture and Streams (getUserMedia and the echoCancellation, noiseSuppression and autoGainControl constraints).
- MDN, MediaDevices.getUserMedia() (permission errors).
Frequently Asked Questions
Built by Derek Giordano · Part of Ultimate Design Tools