Headphone test - check left, right and stereo

Put your headphones on the right way round and set the volume low to start with. Each button plays a clean tone for three seconds.

Start quiet and raise it only if you need to. Sustained tones at high volume are unpleasant and can damage hearing.

Frequency 440 Hz

Drag to sweep. Most adults stop hearing somewhere between 14,000 and 17,000 Hz, and that upper limit falls with age - not being able to hear 16 kHz is normal, not a fault with your headphones.

Are your channels the right way round?

This plays into one ear chosen at random and does not tell you which. Swapped channels are common with a replacement cable or adapter, and almost nobody notices unaided.

Nothing played yet

Press a button to begin.

Tones are generated in your browser rather than downloaded, so the frequency is exact and the channels are truly separate - a compressed audio file can leak signal between them. Nothing is recorded and nothing is sent anywhere.

Three separate questions

People usually mean one of three different things by "test my headphones", and they need different checks.

Is each side working? Play left only, then right only. Silence on one side is a cable, a connector or a driver.
Are they the right way round? Almost nobody checks this, and it is commonly wrong after a replacement cable or a cheap adapter.
Does each side sound the same? Sweep the frequency slider and listen for one side thinning out or buzzing before the other.

Why the channel check is blind

A test that announces "this is the left channel" and then plays it proves nothing - you have been told what to hear, and you will hear it. So the wiring check on this page plays into one ear chosen at random and does not say which. You answer first.

Getting it wrong is the finding, though it is worth repeating two or three times before concluding anything, since a guess is right half the time. If your channels really are reversed, the usual causes are a replacement cable wired incorrectly, an adapter, a balance control pushed to one side in your operating system, or simply wearing the headphones the wrong way round - easier than it sounds when the markings are small.

Reading the frequency sweep

The slider generates a pure tone from 20 Hz to 16 kHz.

Below about 40 Hz most headphones produce very little and small laptop speakers produce nothing at all. That is the hardware, not a fault.
Buzzing or rattling at low frequencies usually means a damaged driver or something loose in the housing.
The top end is about your ears, not your headphones. Most adults stop hearing somewhere between 14 and 17 kHz, and that limit falls steadily with age. Not hearing 16 kHz is entirely normal and is not a fault to chase.

Protect your hearing while testing

Start with the volume low and raise it only if you need to. A sustained pure tone is more fatiguing than music at the same level, and a test of this kind is a poor reason to risk permanent damage. If a tone is uncomfortable, turn it down rather than pushing through.

Why the tones are generated rather than downloaded

Every tone here is synthesised in your browser. That matters for accuracy: an audio file has been through a lossy encoder, and the joint-stereo coding those encoders use can genuinely leak signal between the left and right channels - undermining the very thing a channel test is checking. A generated tone is exactly the frequency stated and is routed to exactly one channel.

Nothing is recorded and nothing is sent anywhere.