Left Right Sound Test
A left right sound test with three big buttons, Left, Center and Right, to check stereo, find swapped speakers or earbuds, and spot mono audio.
Turn your device volume down first.
Start quiet. Turn your device volume down before you play anything, then raise it slowly.
That is a high setting. Lower it before low or high tones, and never raise it with headphones on your ears.
How to use the left right sound test
Press Left, Center or Right. Left plays only on the left channel, Right only on the right, and Center plays both equally so the sound appears in the middle. The panel above the buttons lights the side that is playing, so you can compare what you see with what you hear. Alternate left and right keeps switching sides every 1.6 seconds until you stop it; Include center adds the middle position to the cycle. Under Sound you can pick a chime, noise or a tone.
Keyboard: L, C and R play a side, Space starts or stops alternating, Esc stops. This stereo test works with speakers, headphones and earbuds.
What your result means
| You hear | Likely cause | What to do |
|---|---|---|
| Left on the left, Right on the right | Stereo works | Nothing |
| Left on the right side | Swapped cables, speakers or earbuds | Swap them back and test again |
| Left and Right both on both sides | Mono audio is on, or the device has one speaker | Check the mono setting in the table below |
| One side never plays | A dead side, a loose plug, or balance turned fully to one side | Center the balance, reseat the plug, try other headphones |
| Center leans to one side | Balance off center or one side quieter | Use the balance check on the headphone test |
How to switch mono audio on or off
Mono audio combines the left and right channels into one signal and plays it on both sides. Windows describes it as playing the left and right audio channels into both ears, and recommends it for people who hear with one ear. It also makes this audio balance test show the same sound on both sides, so switch it off while you test stereo.
| Device | Where the mono setting is |
|---|---|
| Windows 11 | Start, then Settings > Accessibility > Audio, switch Mono audio |
| Windows 10 | Start, then Settings > Ease of Access > Audio, switch Turn on mono audio |
| Mac | Apple menu > System Settings > Accessibility > Audio, Play stereo audio as mono |
| iPhone | Settings > Accessibility > Audio/Visual, Mono Audio (the same screen has the left right balance slider) |
| Android | In Accessibility settings; the menu name depends on the phone maker. On Sony Xperia phones: Settings > Accessibility > Audio adjustment, Mono audio |
On a Mac the Balance slider is under System Settings > Sound > Output. On Sony Xperia phones the balance slider is on the same Audio adjustment screen as Mono audio.
Why Center sounds in the middle
Center sends the same sound to both channels at equal level. When two speakers play the same sound in phase, it seems to come from a small spot between them, as Ohm Speakers puts it in their speaker setup advice. The tool uses the browser's stereo panner, which the W3C Web Audio specification describes as equal-power positioning, so the sound keeps about the same loudness as it moves from side to side. For a sound that travels smoothly from ear to ear, try Moving sound on the headphone test, and for each speaker of a home theater, the surround sound test.
More for sound check: Mic Test · Sound Test · Speaker Test · Headphone Test · Bass Test · Surround Sound Test · Audio Delay Test · Speaker Cleaner · Tone Generator
Questions
What is mono audio?
A setting that mixes the left and right channels together and plays the mix on both sides. It is useful with one earbud or hearing in one ear, but it hides stereo, so this test sounds the same on both sides while it is on.
Why is the left sound coming from the right?
The speakers, their cables or the earbuds are swapped. Swap them back, or with earbuds check the L and R marks.
Can I use this stereo test on a phone?
Yes. With headphones it works like on a computer. On the phone speakers, hold the phone sideways in front of you; if your phone has only one speaker, both sides come from the same place.