How do I use the stereo phase comparison?

Press Both, then switch between Same polarity and Opposite polarity. Listen through a stereo output at a comfortable device volume. Stop ends playback; changing a phase setting while stopped does not start sound.

What changes between same and opposite polarity?

The left-channel samples stay unchanged. Same polarity sends identical samples to the right; Opposite polarity reverses the sign of every right-channel sample. The gain is unchanged. Left only and Right only retain their usual signal and silent opposite side.

Why can the opposite-polarity signal become quiet or silent?

Equal opposite samples sum to zero, so a system that mixes the stereo signal to mono can cancel it. Your output settings and processing determine whether that mixing occurs. Silence here is not proof of a broken speaker.

Can this tell me which speaker terminal is positive?

No. The browser cannot sense a terminal, cable, driver movement or room sound. It sends a relative stereo reference; it does not measure electrical polarity, acoustic phase, latency or calibrated sound pressure.

Speaker Phase Test

Compare Same polarity and Opposite polarity by listening. This page opens with Both and Pink noise selected; press Both when ready to begin. The comparison supplies reference signals without measuring electrical polarity or identifying a speaker fault.

Leftready

Rightready

Your device's own volume control still applies. Turn it down before the first press, then raise it until the tone is comfortable.

Signal

Frequency

Volume

20%

Stereo phase, for Both

No pass/fail result is calculated for this listening comparison.

Nothing is playing. Press Both to send pink noise to both channels at 20% of the capped level. Same polarity.

This testsettings only, nothing about you
Speaker test: pink noise, both, volume 20% (-23.1 dBFS). Same polarity.
Levelvolume times the 0.35 ceiling
20% of the capped level, -23.1 dBFS
Loophow the buffer is built
2 seconds of pink noise, crossfaded at the seam and normalised to a peak of one
Pink noisewhat it is for
filtered broadband noise for listening across a range of frequencies; not a calibrated acoustic measurement

Sound on one side onlythe channel is named on screen
Compare Left only and Right only. If one is silent, check the active output and balance, then the cable and speaker. This page cannot distinguish a cable fault from a driver fault.
The sides are swappedwiring, not the browser
Left only names the left channel sent by the browser. If the sound comes from the other side, inspect the output channel assignment and cabling before changing the connection.
Both sides sound identicala mono output cannot be told apart here
A mono setting, a single speaker or an output that mixes the channels can make Left only and Right only sound alike. Separate channel signals do not guarantee separate physical speakers.

Nothing plays until you press a button. The control runs from 0 to 100% of a level capped at 0.35 of full scale, about -9.1 dBFS, and it opens at 20%.

Accuracy. This checks that your speakers make sound and that the left and right channels are the way round you expect. It cannot test your hearing, and it cannot know what happens after the signal leaves the browser: a system equaliser, a mono setting or a Bluetooth speaker that mixes both channels will change what you hear from an unchanged signal.

Common questions

How do I use the stereo phase comparison?: Press Both, then switch between Same polarity and Opposite polarity. Listen through a stereo output at a comfortable device volume. Stop ends playback; changing a phase setting while stopped does not start sound.
What changes between same and opposite polarity?: The left-channel samples stay unchanged. Same polarity sends identical samples to the right; Opposite polarity reverses the sign of every right-channel sample. The gain is unchanged. Left only and Right only retain their usual signal and silent opposite side.
Why can the opposite-polarity signal become quiet or silent?: Equal opposite samples sum to zero, so a system that mixes the stereo signal to mono can cancel it. Your output settings and processing determine whether that mixing occurs. Silence here is not proof of a broken speaker.
Can this tell me which speaker terminal is positive?: No. The browser cannot sense a terminal, cable, driver movement or room sound. It sends a relative stereo reference; it does not measure electrical polarity, acoustic phase, latency or calibrated sound pressure.

This checks that your speakers make sound and that the left and right channels are the way round you expect. It cannot test your hearing, and it cannot know what happens after the signal leaves the browser: a system equaliser, a mono setting or a Bluetooth speaker that mixes both channels will change what you hear from an unchanged signal.