Six checks that need nothing but this page and your ears: channels, balance, how high you can hear, how low your pair reaches, phase, and seal. Everything is generated on your device; nothing is uploaded. Start at the low volume it opens at.
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A pulse plays in the left ear, then the right. The letters light up to show which side should be sounding.
What it means. If the lit letter and the ear you hear it in disagree, the cable or an app setting is swapped; true wireless buds can also re-pair swapped after a reset. If one side is silent, try another source before blaming the pair.
The same 440 Hz tone alternates left, right, left, right at identical level. Both should feel equally loud.
What it means. A small difference is normal between ears. A clear, repeatable difference at the same source level points to a failing driver, a partly blocked grille on earbuds, or a balance slider someone nudged in the OS.
A smooth sweep from 20 Hz to 20 kHz over 25 seconds. Tap the big button the moment the tone disappears for you.
What it means. Most adults top out somewhere between 14 and 17 kHz and it drifts down with age; that is your ears, not your gear. If the tone vanishes below about 12 kHz on a pair that is specified flat to 20 kHz, the pair (or a Bluetooth codec under pressure) is rolling off early. Tinny tones near the top are normal; do not chase them with volume.
Pure tones at the bottom of the range. Play from the lowest up and note the first one you clearly hear as a tone rather than a flutter or a buzz.
What it means. Open-back and small earbuds often fade below 40 Hz; sealed over-ears and well-fitted in-ears usually hold 25 to 30 Hz at moderate level. A buzz instead of a tone at the lowest steps is a driver bottoming out or, on earbuds, a broken seal; push the tips in a little and try again. Never turn up to find bass: low tones at high level are the fastest way to damage a driver.
Three seconds of noise with both channels in step, then three seconds with one channel inverted. In-phase noise sits in the centre of your head; inverted noise feels wide, hollow and hard to place.
What it means. A is the correct one. If B felt centred, one driver is wired out of phase (a re-cabled or repaired pair is the usual suspect) and bass will cancel in the middle of the image.
Steady noise for ten seconds. While it plays, snap your fingers by each ear, then tap the keyboard. With a good seal both sound distant and dull; with a leak they cut straight through.
What it means. On earbuds, seal is everything: the wrong tip size loses most of the bass and all of the isolation before you ever touch an EQ. On over-ears, glasses arms and a loose clamp do the same. Active noise cancelling cannot fix a leak; it needs the seal first.
Passed everything? Keep the noise: our sibling project alltherightnoise.com runs ocean, rain, brown and pink noise for focus and sleep, on the same kind of engine this page uses.