🎧Headphone test

✓ Tested & verified Updated: Aug 11, 2026 How the test works

Headphone test

1Left channel only — the tone should sit in your left ear.
2Right channel only — the tone should sit in your right ear.
3Both in phase — the tone should feel like it is in the middle of your head.
4Both out of phase — the same tone should feel wide, hollow and hard to place.

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Four tones, four answers. Step 4 is the one no other tester runs: the same tone with one side inverted tells you whether the wiring is in phase.

Left—
Right—
Phase—
Tone440 Hz

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How do I check headphone left, right and phase?

The headphone test names the channel before you hear it, then plays both channels together in phase and out of phase — three checks that cover almost every fault a browser can see. Left and right catch swapped channels, a dead driver and a plug that is not fully home. The phase check catches the one fault people notice without being able to name it.

Two identical signals in opposite polarity cancel each other in the middle of the stereo image. In phase, a centre tone sits solidly between your ears; out of phase it smears outward, the bass thins, and the sound seems to arrive from behind you. If the in-phase and out-of-phase versions are indistinguishable, one channel is wired backwards — and that is far more often a cable or an adapter than the headphones themselves.

Run the checks in order and stop at the first result that surprises you, because each one clears a different part of the chain between the browser and the drivers.

What you hear	What it means	Where to look
Left on the left, right on the right	Routing is correct end to end	Nothing to fix
Channels swapped	Something between the application and the drivers reverses them	A reversed extension cable, a virtual surround mode, or the pair worn back to front
One side silent	That channel never reaches the driver	Push the plug fully home, try another jack, flex the cable near the plug
One side quieter	Balance, or a partly blocked driver	The balance slider first, then the mesh over the quieter side
Both sides play, but nothing will sit in the centre	Polarity error on one channel	The cable or adapter, rather than the headphones
Muffled and thin on both sides	Mono hands-free profile on a wireless headset	Release the headset microphone, or select the stereo output device

A headset has two halves and they fail separately: when people say you sound distant while your own ears are perfectly happy, the problem is on the input side and belongs to the mic test. Speakers follow the same left-right convention on different hardware, which the speaker test covers.

Frequently asked questions

Left and right are swapped. Is it the headphones or the computer?

Move the headphones, not the settings. Plug the same pair into a phone: if the sides are still reversed there, the fault travels with the headphones or their cable. If they are correct on the phone, the reversal belongs to the computer, which in practice means a spatial audio or virtual surround mode, an extension lead wired the other way, or a docking station presenting its own audio device.

What does out of phase actually sound like?

Hollow and unstable. A voice or tone that should be centred stops sitting in the middle of your head and spreads to both sides, the bass loses its body, and small head movements change the effect. On its own it is easy to miss, and it becomes obvious the moment you switch between the in-phase and out-of-phase versions of the same sound — which is exactly why the test plays them back to back.

One side is quieter than the other. Is the driver failing?

Check three cheaper causes first. The balance slider in the system sound settings drifts more often than anyone expects; the mesh over one driver collects dust and wax and quietly takes several decibels off the top end; and a four-pole headset plug in a three-pole jack sits at the wrong depth, which can leave one channel weak and add a hum. A failing driver is the answer only after those three.

My headphones sound fine here but terrible in a call

That is the hands-free profile. When an application opens the microphone on a wireless headset, Bluetooth switches the device from stereo A2DP to a mono voice profile, and the sound quality collapses in the same instant — narrow bandwidth, no stereo image, and an audible drop in level. Using a separate microphone and leaving the headset on its stereo profile is the only fix that keeps both.

Can this measure my headphones' frequency response?

No, and no web page can. A response measurement needs a calibrated coupler, a measurement microphone and a known signal chain, while a browser has no idea what the system equaliser, the headphone amplifier or the drivers are doing to the signal. What it can establish is routing, channel identity and relative polarity — which are the things that actually go wrong day to day.

How loud should I set the volume for this?

Lower than you would for music. The channel checks work at any level, and the polarity check is easier to judge quietly, because the collapse of the centre image is a spatial cue rather than a loudness one. Start at roughly a third of system volume and adjust before a tone starts rather than during it, so nothing arrives louder than you expected.

How the test works

Each check is a signal with a known channel assignment, generated in the page rather than downloaded. The left check plays a tone on the left channel while the right channel carries digital silence, and the right check is its mirror image. The phase check plays the same tone on both channels at once: in phase, both channels carry identical samples; out of phase, one channel is multiplied by −1, so the two waveforms are equal and opposite. Anything that sums the two channels — a mono speaker, a mono Bluetooth voice profile, some spatial audio modes — makes the out-of-phase version nearly silent, which is useful information about the device rather than a fault in the test. The page reports what it is sending; judging what arrives is the listener’s part, because a browser cannot hear the result. Nothing is recorded and nothing leaves the browser.

Sources:

Three faults, and the order to rule them out

Channel identity comes first. Everything after it assumes you know which side is which, so a swapped pair quietly invalidates every judgement you make later in the session.

Then level symmetry. A quiet side is far more often a balance setting or a blocked mesh than a failing driver, and both of those cost nothing to check before you start shopping.

Polarity last. It is the rarest of the three and the hardest to hear, and it is also the only one that survives every other check looking completely fine.