This left right headphone test plays a 440 Hz tone that jumps from one side to the other every second. While it plays, the highlighted button (Left or Right) shows where the sound should be coming from. If you hear it on the correct side both times, both channels work and your headphones aren't reversed.
It works with wired headphones, Bluetooth earbuds, gaming headsets and stereo computer speakers. The sound is generated in your browser, with no file to download and no app to install. Frequency, volume and waveform use the same controls as the tone generator.
How to use it
- Put your headphones on following the L and R marks, and turn the device volume down first.
- Press Play. The tone starts on the left and moves to the other side every second; the highlighted button shows which side is playing.
- Check that what you hear matches the highlighted button. If the sound comes from the opposite side, the channels are swapped.
- To hear one side for longer, tap Left or Right: switching stops and the tone stays there. Both plays it in the center.
Why sound only comes out of one side
The usual suspects are a 3.5 mm plug that isn't fully inserted (a phone case or lint in the jack can block it), a broken wire near the plug or the earcup, and, on Bluetooth earbuds, one bud with a dead battery or out of sync. With the tone playing, slowly rotate the plug: if the silent side cuts in and out, the plug or cable is the problem.
For true wireless earbuds, put both buds back in the case, take them out again and rerun the test. If that doesn't help, forget the device in your Bluetooth settings and pair it again.
Mono vs stereo headphones, and system balance
If you hear the same sound in both ears even with Left selected, either the headset is mono or mono audio is turned on. On iPhone and Android this setting lives under Accessibility, next to the left/right balance slider; on Windows it's in the sound settings. A balance slider pushed to one side explains one ear being quieter.
Tips
- Before blaming the headphones, make sure you aren't wearing them backwards: L goes on the left ear.
- To check bass and treble, run a 20 Hz to 20 kHz sweep in the tone generator.
Frequently asked questions
Why do my headphones only play on one side?
Most often it's a loose or dirty plug, a broken wire near the plug, or a Bluetooth earbud that is out of battery or disconnected. Try another device: if the problem stays, it's the headphones; if it goes away, it's the jack or a setting on the device.
How do I know if my left and right are reversed?
Press Play and watch the highlighted button. If it says Left and you hear the tone in your right ear, the sides are swapped. Check that you're wearing the headphones the right way round; if you are, the cable, adapter or headphones themselves have the channels reversed.
Does my phone have a left/right balance setting?
Yes. On iPhone it's in Settings, Accessibility, Audio and Visual, with the balance slider and Mono Audio. On Android it's under Accessibility (the name varies by brand: Audio adjustment, Mono audio, Audio balance). Keep the balance centered for this test.
The channel buttons are greyed out. What now?
Your browser can't split the channels. Update it or use a recent version of Chrome, Edge, Firefox or Safari.
One side is quieter than the other. Is it broken?
Check the system balance first and clean the earbud mesh, since earwax and dust muffle the sound. If one side is still quieter with the balance centered, that driver may be failing.