Click Play Left, Play Right, or Play Both; use headphones to confirm each channel.
Click Play Left, Play Right, or Play Both. A short tone plays through that channel only - nothing is uploaded.
Test left and right speaker channels with a short in-browser tone. Click Play Left, Play Right, or Play Both; adjust the frequency, then Stop. Everything runs in the browser - no microphone, no upload, and no account.
Does this use my microphone?
No. The tone is generated with the Web Audio API. Nothing is recorded and no microphone permission is requested.
Why do I need to click Play?
Browsers block autoplay of audio until you interact with the page. A click on Play Left, Play Right, or Play Both starts the AudioContext.
How do I tell left from right?
Use headphones. Play Left should be louder in the left ear; Play Right in the right ear. Play Both sends the same tone to both channels.