Left Right Audio Test
Check that left and right are on the correct sides of your headphones or speakers, and that your speakers are wired in phase. Free stereo test.
Volume warning: test tones start quiet. Raise the volume slowly. Loud tones, especially bass and high frequencies, can damage speakers and hearing.
How to test
- 01Put on your headphones, or sit centred between your speakers.
- 02Play Left, then Right. Each should come only from that side.
- 03Play the pan sweep: the sound should move smoothly from left to right.
- 04Speakers only: compare In phase and Out of phase (below).
Why channels end up swapped
- Speaker cables swapped at the amplifier or speaker end.
- Headphones or earbuds worn the other way round. Most are marked L and R.
- Mono audio turned on in accessibility settings, which plays the same sound on both sides.
- The balance slider moved to one side in the sound settings.
What speaker phase means
Each speaker has a positive and a negative terminal. If one speaker is wired the other way round, its cone moves out while the other moves in. Bass from the two cancels, and the sound loses its centre and feels vague.
The phase test plays the same bass-heavy noise on both speakers, once normally and once with one side inverted. Wired correctly, 'In phase' sounds fuller and centred between the speakers. If 'Out of phase' sounds fuller, swap the two wires on one speaker.
What your result means
Left and right come from the right sides
Your channels are correct.
Nothing to fix.
Left and right are swapped
Cables swapped, or headphones worn the other way round.
Swap the cables or flip the headphones.
Both sides play the same sound
Mono audio is turned on, or the device is mono.
Turn off mono audio (see the fixes).
'Out of phase' sounds fuller than 'In phase'
One speaker is wired backwards (+ and − swapped).
Swap the two wires on one speaker.
How to fix it
Windows
- Settings → Accessibility → Audio: turn off Mono audio.
- Control Panel → Sound → your device → Properties → Levels → Balance: set left and right equal.
Mac
- System Settings → Accessibility → Audio: turn off 'Play stereo audio as mono'.
- System Settings → Sound → Output: centre the Balance slider.
iPhone
- Settings → Accessibility → Audio & Visual: turn off Mono Audio and centre the balance.
Android
- Settings → Accessibility → Audio adjustment (name varies): turn off Mono audio and centre the balance.
Speakers out of phase
- On one speaker only, swap the red (+) and black (−) wires.
- Play the phase test again: 'In phase' should now sound fuller and more centred.
Questions
How do I know which earbud is left?
Play Left. The earbud that plays it is your left one. Most are also marked L and R.
What does 'out of phase' mean?
One speaker's cone moves out while the other moves in, so bass cancels and the sound feels vague. It happens when + and − are swapped on one speaker.
Why is only one earbud playing?
Check the balance and mono settings, then charge and re-pair the earbuds. If one is still silent, clean its mesh or contact the maker.
Is anything uploaded?
No. The test runs entirely in your browser. Nothing you see, say or film is sent to us or stored anywhere.