Microphone Test
Press start, say something, and watch the waveform move. What this page answers is "is it picking up sound, and does it ever drop out" — not "how sensitive is it". The reason sits right next to the readouts below.
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Why these are not sound pressure levels
getUserMedia enables three processors by default: automatic gain (AGC) turns quiet input up and loud input down; noise suppression (NS) erases steady background sound; echo cancellation (AEC) subtracts part of your own voice. Together they mean the analyser is no longer seeing what the microphone received. So the numbers answer "is there sound, does it drop out", not "is the mic sensitive enough" or "how loud is this room".
What dBFS means
Decibels relative to full scale: 0 dBFS is the largest value the digital signal can hold, and silence is −∞. It is a relative quantity with no physical unit — the same room and the same sentence on a different laptop can read completely differently. To compare against anyone else, use a real sound level meter.
When this page is genuinely useful
(1) A new microphone or headset — is it picking up anything at all? (2) People on the call cannot hear you. (3) Verifying "am I muted?". (4) Watching for the waveform cutting out on a flaky cable. All four get a clear answer, immediately.
Questions
First check whether the browser was granted permission (the icon at the left of the address bar). Then check the default input device in the OS — the browser gets whatever the system offers first. Also: some headsets have a hardware mute button, and software cannot see that.
No. The stream only reaches the browser’s analyser (AnalyserNode), which yields frame-by-frame sample values. Nothing is stored, uploaded, or playable. The microphone is released the moment you stop.
This page uses the system default — whatever the browser is handed first. Change it in the OS or in the site permissions. A device dropdown is deliberately omitted: before permission is granted, device labels are blank, so the dropdown would be a list of empty entries.
getUserMedia requires a secure context — on a non-HTTPS page the browser refuses outright without even prompting. That is a browser rule. The live site is HTTPS and localhost counts as secure, so local development is unaffected.
