Left / right channel check · Stereo balance · Auto-alternate · Tone & volume control. Put your headphones on and press play.
This tool plays a clean test tone to your left channel, right channel, or both, so you can confirm your headphones, earbuds, or speakers work correctly. It checks for the three most common stereo faults: a dead side, swapped channels, and unbalanced volume. It runs entirely in your browser on any phone, tablet, or computer — nothing to install.
A correct pair confirms three things: that both channels work, that they are not swapped (left playing on the right), and that they are balanced in loudness. These are the most common faults in cheap, worn, or counterfeit earbuds, and the first things to check on a used pair.
Put your headphones or earbuds on, set a comfortable volume, then press Left Only. The tone should come from your left ear only — the left panel lights up to confirm which channel is playing. Repeat with Right Only and Both. Use Auto-Alternate to bounce the tone between channels automatically, a quick way to confirm stereo separation and that both sides are balanced at the same volume. Adjust the Tone slider to test how each ear handles low, mid, and high frequencies.
If Left Only or Right Only plays no sound, that side's driver or wiring has failed. Try wiggling the cable or cleaning the earbud mesh first — a common cause of one-sided silence is debris or a loose connector.
If Left Only plays in your right ear, the channels are reversed. Usually the headphones are simply on the wrong ears — check the L/R markings near the earcups before assuming a wiring fault.
Use Auto-Alternate to compare loudness between sides. If one is clearly quieter, check your device's audio-balance setting first, then suspect a failing driver if the balance is centered.
Run Left, Right, and Both before you pay, then sweep the Tone slider to make sure each side reproduces low and high frequencies cleanly without crackle. It takes ten seconds and catches the most common defects.
Start low and raise the volume gradually. A continuous tone can sound harsher than music at the same level, and prolonged loud tones can be uncomfortable. This tool caps its output below the system maximum, but you should still keep the volume moderate to protect your hearing.
Browsers block audio from starting automatically and only allow it after you interact with the page. That is why the test begins the moment you tap Left, Right, or Both — it is expected behavior, not a bug.
Yes, as long as they are connected and selected as your device's audio output. The test plays through whatever output your system is currently using, so confirm your Bluetooth headphones are the active output before testing.
Press Left Only and pay attention to which ear hears the tone. If it plays in your right ear instead, the channels are reversed — either your headphones are physically on the wrong ears, or (rarely) the wiring is reversed. Most headphones mark L and R near the earcups; check those markings.
First check your device's audio balance setting (on iPhone: Settings → Accessibility → Audio/Visual → Balance; on Android: Settings → Accessibility → Audio balance) and make sure it's centered. If it's centered and one side is still quieter, the driver or cable on that side is likely failing, or debris is blocking the mesh. Clean the earbud and test again.
Yes. With external stereo speakers, Left Only should play from the speaker on your left and Right Only from the one on your right. This is the fastest way to check that a stereo speaker pair is wired correctly and positioned on the right sides.