The six checks
1Check both channels
Play a left-only, then right-only signal and confirm each side plays alone at equal volume. Uneven or missing channels usually mean a damaged cable or a failing driver - the most common headphone fault.
2Verify the stereo image
Play a centered tone: it should form a phantom image floating exactly in the middle of your head. If it sits off to one side, one driver is quieter; if it feels diffuse and directionless, check polarity next.
3Check wiring polarity
Compare an in-phase and polarity-inverted signal. On correctly wired headphones the in-phase version sounds fuller and centered; if the inverted one sounds more normal, the pair or its cable has a wiring fault.
4Find the frequency limits
Sweep from 20 Hz upward: good over-ears produce audible (and feelable) output by 20-30 Hz, budget earbuds often start near 50-80 Hz. Then sweep the top: the limit you find is usually your ears rather than the headphones - compare against your hearing-test ceiling.
5Listen for distortion and rattle
Play a loud-ish 40-60 Hz tone and listen for buzzing or crackling - a torn driver or trapped hair (common and fixable) buzzes clearly on bass tones. A clean sine should sound perfectly smooth at any safe volume.
6Measure Bluetooth latency
Wireless pairs add 40-300 ms of delay depending on codec. Measure yours: under ~100 ms is fine for video with compensation, under 60 ms for gaming. High readings mean checking which codec your devices negotiate.
Reading the results
One quiet side: before blaming the driver, clean the mesh/filter (earwax is the top cause in earbuds), wiggle the cable at both ends while a tone plays (crackling = broken conductor), and check OS balance settings. A cable that changes the sound when flexed is repairable; a driver that buzzes on clean bass tones usually is not.
Bass sounds weak: with in-ears, 90% of the time it is seal, not hardware - try larger tips. A sealed in-ear that measures fine to 20 Hz can lose everything below 100 Hz through a leaky fit. Confirm with the sweep: reseat, and watch the low end appear.
High latency on Bluetooth: the codec is negotiated per connection - the same headphones can run low-latency aptX on one phone and laggy SBC on another. Check your device's Bluetooth developer settings, and see the codec table in our latency test.
Everything passed? Finish by checking the one component you can't replace: your ears. Our hearing test gives you a frequency ceiling to compare year over year, and our safe-listening guide covers keeping it there.
Headphone Testing FAQ
How do I test if my headphones are working properly?
Run five quick checks: left/right channels play separately at equal volume, a centered tone images in the middle, an in-phase signal sounds fuller than an inverted one (polarity), a 20 Hz-20 kHz sweep plays smoothly without dropouts or buzzing, and bass tones around 40-60 Hz sound clean at moderate volume. All five take about five minutes with free browser tools.
Why is one side of my headphones quieter?
In rough order of likelihood: a partially blocked earwax filter or grille on that side, a damaged cable near the plug or the earcup (wiggle it while playing a tone to confirm), OS balance settings shifted off-center, or a genuinely failing driver. A steady test tone makes the comparison far more reliable than music.
What frequency should headphones go down to?
Most quality over-ear and in-ear headphones produce usable output to 20 Hz - in-ears often lowest of all thanks to the sealed ear canal. Open-back headphones and small earbuds commonly roll off below 40-60 Hz. Test with a slow upward sweep and note where you first hear (or feel) the tone.
Does headphone burn-in improve sound?
Controlled measurements find little to no change in headphone response after extended playback - blind tests suggest most reported burn-in is your brain adapting to a new sound signature plus fresh ear pads settling. There is no harm in it, but there is no need to run noise for 100 hours before judging a pair.
How can I tell if used or second-hand headphones are worth buying?
Run the full five-minute check before paying: channel balance and polarity catch cable damage, the bass distortion check catches torn drivers, the sweep catches dead zones, and a latency test catches aging Bluetooth radios. A pair that passes all five is functionally healthy regardless of cosmetic wear.