स्पीकर और हेडफ़ोन टेस्ट (बायां/दायां).

Tones are generated by the browser; very low and very high frequencies depend on your speakers. Everything is calculated in your browser; nothing you type is uploaded.

Sine tones are routed with a stereo panner; sweeps glide exponentially between frequencies; the phase test sends the same tone to both channels, in phase or inverted.

The left tone is heard only in the left ear; on the inverted-phase test the sound becomes thin and diffuse, as it should.