EarWitness

⏺ quick start

1. 01Put your iPhone near the sound source — a foot or two away, stationary, screen up.
2. 02Press ▶ START and leave it running. EarWitness listens and analyzes in real time.
3. 03Read the verdict: ⏺ LOOP DETECTED with the measured period, or ⏺ no loop detected.

⏺ frequently asked

? How does detection actually work?

EarWitness listens for a section of audio that repeats. It compares an early slice of what it hears against everything after it (normalized cross-correlation), and when the same pattern comes back around — twice or more — it reports the spacing between repeats as the loop period.

? Why does it need the microphone?

It has to hear the sound to test it. Audio is analyzed live, on your device, and discarded when you stop — nothing is recorded or uploaded. See the privacy policy for the full detail.

? It says "no loop" on a machine I think is looping. Why?

Usually the session was too short to hear the loop come around twice, or the loop is longer than the time you gave it. The detector needs at least two full repetitions to confirm.

? I get "input near clipping." What do I do?

The signal is too loud and is overloading the mic, which corrupts the analysis. Move the phone further from the source (or turn the source down) until the warning clears.

? Does it work on anything, or just white noise?

Any repeating audio — sleep machines, ambient tracks, HVAC hum, mechanical cycling, "seamless" background loops. The limits are simple: the full loop has to fit within one session, repeat at least twice, and be at least a couple of seconds long.

? Can I test a recording I already have?

Yes. Run an existing file through the same detector for offline validation — handy for audio you captured elsewhere. It's read and analyzed locally; nothing is uploaded.

? Can I save what it found?

When a loop is detected you can export it: $ export-loop saves one loop as an M4A, and $ save-raw saves the full recording as a WAV — both written to a location you choose on your device.

? Is my audio private?

Completely. Everything runs on your iPhone. There's no account, no analytics, and no server for your audio to go to. The App Store listing shows "Data Not Collected" because that's literally true.

⏺ still stuck?