AudioMeter

AudioMeter uses an Android device's microphone as a level meter. Incoming sound is shown on a VU-style scale, the moving readout familiar from recording equipment, so changes in relative loudness are visible as they happen instead of arriving as a single figure.

The scope is narrow by design: the app is a meter, not a recorder or an editor. It suits checking whether a room, a rehearsal space or a piece of machinery is louder or quieter than before, or judging levels by eye before recording elsewhere. Readings come from the handset's built-in microphone and reflect its response, so the numbers are useful for comparison rather than as calibrated measurements.

It is an Android application with no build for other systems, and the source is available under GPL-3.0-or-later.