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Left Right Audio Test
The quickest way to prove which side is which, with a blind identification game.
- Available — Live on this site right now.
- Browser Tool — Runs in the browser you are reading this in.
- No Install — Nothing to download, no extension, no account.
- Client-Side — Runs entirely on your device. No test data is uploaded.
- Plays Sound — Produces audio, so speakers or headphones are needed.
This page explains the tool. The tool itself is one click away and needs no sign-in.
Open Left Right Audio TestWhat is this tool?
This tool answers one question thoroughly: is each side doing what it should? It isolates left and right, plays a phantom centre and a summed mono signal, sweeps between the sides, and alternates between them at your choice of speed.
It also includes a channel identification exercise — the page plays a side without telling you which, and you guess. That is the only honest way to confirm your channels are correctly assigned, because knowing the answer in advance changes what you think you hear.
Seventeen frequency presets from 20 Hz to 20 kHz let you check whether a channel problem is confined to part of the range, which is common with a failing driver.
How to use it
- Press TEST LEFT and then TEST RIGHTConfirm both sides produce sound. Do this at a low volume with the 1 kHz preset, which is where hearing is most sensitive and where every speaker and headphone works.
- Play the phantom centrePLAY CENTER (PHANTOM IMAGE) sends equal signal to both sides. It should appear to come from directly between the speakers, or from the centre of your head on headphones. If it does not, the two channels are not matched.
- Play mono audioPLAY MONO AUDIO sums both channels. Compare it with the phantom centre: a large drop in level or body means the channels are partly cancelling, which is a phase or polarity problem.
- Use the sweeps and the alternating modesLEFT → RIGHT SWEEP and RIGHT → LEFT SWEEP should glide. ALTERNATING (1.0s) and FAST (0.5s) switch back and forth — the faster mode makes a small level difference much easier to hear, because your ears compare rather than remember.
- Try the blind identification exerciseLet the page choose a side and guess before looking. Getting it consistently wrong is the clearest possible evidence that your channels are reversed, and it costs nothing to check.
- Test the balance positions100% LEFT, 50% LEFT, CENTER, 50% RIGHT and 100% RIGHT. The 50% positions should sound clearly off-centre but still present on both sides. They are useful for confirming the panner is working across its range, not just at the extremes.
What the results mean
Both channels work, directions correct
What you want. The label on the button matches the side you hear, on every frequency you tried.
No sound on one side
Check the system balance slider, then the cable and connector, then the device. On wired headphones this often means a broken conductor near the plug — wiggling the cable at the plug while a tone plays will usually confirm it.
Reversed left and right
The identification exercise is what proves this. It is a wiring or configuration problem: swapped speaker cables, a reversed adapter, or headphones worn the wrong way round. The page has a section on fixing it.
One side louder
Compare using the fast alternating mode rather than by playing each side once. If the imbalance persists on headphones, it is the headphones or the system balance; if it only happens on speakers, suspect placement and room.
A channel that fails only at some frequencies
Step through the presets on the suspect side. A driver that works at 1 kHz but not at 8 kHz points at a failed tweeter in a multi-driver speaker, or a partially damaged headphone driver.
Buzzing or rattling on one side only
Almost always mechanical and specific to that transducer. It is a genuine hardware finding rather than a configuration issue.
What it can detect
- A silent channel
- Reversed left and right assignment, confirmed blind
- A level imbalance between channels
- A channel that fails only in part of the frequency range
- Phase and polarity problems, from the centre-versus-mono comparison
Limits worth knowing
A browser can only report what the platform gives it. These are the honest boundaries of this page, so a result is never read as more than it is.
- The page has a “Browser Audio Test Limitations” section and its FAQ asks “Can a browser test physical speaker hardware?”, “Can this test measure speaker crosstalk?” and “Can this test measure SPL?” No to all three. The tool sends a known signal; the assessment is what you hear.
- No microphone is used, so nothing about the sound in the room is captured or measured.
- The browser cannot change your channel assignment. If left and right are swapped, the fix is in the cabling or the operating system's audio configuration.
- On speakers, both ears hear both speakers, so perfect separation is impossible by physics. Headphones are the reference for separation questions.
Tips
- Do the identification exercise before you look at any labels. Once you know the answer, you cannot un-know it, and expectation is a powerful bias in listening tests.
- Use 1 kHz for channel presence and 250 Hz or lower for phase. The two questions want different frequencies.
- If you suspect a cable, play a continuous tone on the suspect side and flex the cable gently along its length. Dropouts localise the break.
Troubleshooting
My left earbud is silent but it worked yesterday.
Test it on another device to separate the earbud from the computer. On true wireless earbuds, re-pairing often fixes a channel that has dropped out; on wired ones, suspect the cable near the plug.
The centre image is inside my head on headphones but not between my speakers.
That is normal. Headphones place the phantom centre inside your head because each ear hears only one driver. On speakers the centre depends on symmetry and room reflections.
Left and right are swapped only in games.
Then the browser test has done its job — the hardware is fine and the game's own audio configuration is inverted. Check its channel or surround settings.
Both channels are fine here but one side crackles with music.
Crackling with content but not with a pure tone usually means a marginal connection or a driver being pushed harder by loud passages. Retest at higher volume with the sweep and see whether it appears.
Ready to run it?
The quickest way to prove which side is which, with a blind identification game. Nothing to install, and it opens in this browser.