Phone audio
Compare a sound, keep its context, then try a reload without a network.
1 · Secure and ready
Open this page over HTTPS. The first visit needs the internet. No account is needed.
Preparing offline copy…
To install, use your browser's Install app option. On iPhone, open in Safari, then Share → Add to Home Screen. If no install option appears, keep using this browser tab.
For the offline check, wait for “Offline copy ready”, turn off Wi-Fi and mobile data, then reload this page. Reconnect when finished.
2 · Listen with permission
Keep the microphone uncovered. Use a quiet room and a gentle hum; avoid loud sounds.
Not started. Microphone off.
No level reading yet.
The level is relative to the browser's full scale (dBFS). More negative is quieter. It is not calibrated dB(A) or a sound-pressure reading.
3 · Look at the spectrum
Waiting for a microphone reading.
Low frequencies are on the left; higher ones are on the right, up to half the sample rate. A larger FFT gives finer bins but a longer time window. Bin spacing alone does not prove two tones can be separated.
Microphone settings actually applied
Not started.
4 · Keep a local record
0 saved records. Nothing is sent.
Inspect the latest record
No saved record.
Only short summaries are saved, never raw audio. Up to 20 records stay in this browser. This lab has no upload service: “local only” never means “sent”. Clear records when finished. Repeat the test after changing phone, placement, browser or FFT size.