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Left-Right Swap Detector

Six randomised tones settle whether your channels are reversed.

Volume warning

This test plays tones that can be loud and may damage hearing or speakers. Turn your volume down before starting, then raise it gradually.

How this test works

Six tones play, each sent to one channel, in an order you cannot predict. You say which side you heard each one on, and the pattern of answers decides the result. Randomising the side is the entire reason this test works where a fixed order does not: if you know the left tone is next, you will hear it on the left. The sequence is a shuffle of exactly three lefts and three rights rather than six coin flips, because a truly random run can easily produce five of one side, and a run of five lefts makes the sixth trial predictable in precisely the way randomisation is meant to prevent. Every tone is the same pitch, since varying it by side would give you a second cue to answer from. Four of six answers agreeing one way is treated as no answer at all, and reported as inconsistent.

What the results mean

Correct
You placed at least eighty per cent of tones on the side they were sent to. Left is left, right is right, and stereo material will image the way it was mixed.
Swapped
You consistently placed tones on the opposite side. The channels are crossed somewhere between the browser and your ears. Both work — they are the wrong way round, which is a cable, a connector or how the headphones are being worn.
Mono / centre
Most tones arrived in the middle. Your output is combining both channels, which is correct for a phone speaker or a soundbar and is not a fault. On stereo headphones, look for a mono audio accessibility setting.
Inconsistent
The answers did not agree strongly enough to call it either way. Nearly always one earbud in, or speakers placed too close together to distinguish. The test reports this rather than picking whichever answer had one more vote.

Common problems and fixes

You suspect a swap but the result comes back correct
Then the recording or the app is doing it, not your hardware. Some films and games have shipped with reversed channels, and a video player with a surround downmix setting can invert the image on its own.
The result is inconsistent every time
Wear both sides of the headphones, or move the speakers further apart and sit between them. Placing a sound needs two ears receiving different signals — with one earbud in there is nothing to compare.
It says mono but you are on stereo headphones
Check for a mono audio setting under accessibility on your system. It is on by default on some devices, is easy to enable accidentally, and is inaudible on speech — which is why it usually goes unnoticed until a test like this.
One side is missing entirely
Run the channel isolation test instead. This one is built to decide between straight and crossed, while that one is built to separate a dead channel from a swap, which is a different question.

Frequently asked questions

Why does the order have to be random?

Because expectation is a powerful thing in hearing. Told that the left tone is coming, most people hear it on the left even when it is not — the effect is well documented and strong enough to invalidate any fixed-order test. Shuffling removes the expectation, and six trials mean one confused answer cannot decide the result.

Why three of each side rather than six random ones?

A run of five lefts is entirely possible with independent random choices, and by the fifth you would be answering from the pattern rather than the sound. Fixing the counts at three and three also keeps the correct-versus-crossed ratio meaningful, since both are being measured against the same denominator.

Does a swap damage anything?

No. Everything plays at full quality and nothing is stressed. It affects the stereo image only — instruments and effects land on the wrong side, and directional cues in games and films point the wrong way. Most people experience it as a vague sense that something is off rather than as an identifiable fault.

Could a surround or spatial audio feature cause this?

Yes, and it is worth ruling out before rewiring anything. Spatial audio, virtual surround and several headphone enhancement modes deliberately move channels around, and any of them can produce a confident swapped result on hardware that is wired correctly.

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