Headphone Test — Left/Right, Stereo, Phase & Bass in 4 Steps
Put your headphones or earphones on and work down the steps. The L button sits on the left of the screen — the sound should come from the left too.
Set your volume to about half before starting. The bass step in particular can feel suddenly loud.
1Left / Right
2Stereo sweep
A tone glides from left to right over three seconds. It should travel smoothly without dropping out or jumping.
3Phase check
In phase, the sound focuses in the middle of your head; out of phase, it smears and sounds hollow. If the inverted one sounds more focused, your wiring or drivers are reversed.
4Bass check
The lower the frequency, the harder it is to reproduce. Good headphones make even 40Hz felt as a rumble.
Press a button to play a tone.
About the Headphone Test
When headphones misbehave, it is almost always one of four things: the sides are swapped (on your head or in the wiring), the stereo image breaks somewhere between the ears, the phase is inverted and the sound loses its focus, or the bass simply is not being reproduced. This test checks those four things in order.
Step one is orientation — press the L button on the left of the screen and the tone must appear in your left ear. Step two sweeps a tone from left to right to prove the stereo image is continuous. Step three plays the same tone in phase and out of phase: in phase it snaps to the center of your head; out of phase it smears and hollows out. If the inverted version is the one that sounds focused, a cable or driver has its polarity flipped. Step four plays 40, 60, 80 and 100Hz. Most small earphones manage 100Hz; making 40Hz felt as a rumble is what separates good drivers from adequate ones.
Every tone is generated as a sine wave inside your browser — no files, no microphone, nothing transmitted. To check the playback device itself, use the speaker test; to find your own hearing ceiling, the hearing test is next door.
How the headphone test works
- Put your headphones on and set the volume to about half.
- Use the L and R buttons to confirm each side plays where it should.
- Play the sweep and listen for a smooth left-to-right glide with no gaps.
- Alternate in-phase and out-of-phase; the focused one should be 'in phase'.
- Walk the bass buttons down from 100Hz to 40Hz and note where the rumble stops.
- Found a fault? Repeat with another device or cable to isolate the cause.
Frequently asked questions
I pressed L but heard it on the right.
Most often the earphones are simply on the wrong ears. If they are on correctly and still reversed, a cable, adapter or Bluetooth link is swapping the channels. Try another device: if the swap follows the headphones, it is the headphones.
Why does phase matter?
If the two drivers move in opposite directions, sounds that belong in the center — vocals above all — smear out and the bass thins. If singers sound strangely distant in music, suspect phase. For wired sets check for damage or repairs; for wireless, re-pair the connection.
I cannot hear 40Hz. Is that a defect?
More likely a limit than a defect. Many small earphones and most laptop speakers barely reproduce 40Hz at all. Hearing the rumble from 60Hz up is ordinary performance; feeling 40Hz is the mark of genuinely good bass. Note that very low volume hides bass regardless of quality. That trade has a name and a published standard behind it. ISO 226, Normal equal-loudness-level contours, reached a third edition in 2023, and it specifies which combinations of sound pressure level and frequency are perceived as equally loud by human listeners, given frequency by frequency across the one-third-octave series from 20 Hz to 12 500 Hz. So 40 Hz sits inside the range that has been measured rather than past the edge of it. One caveat travels with those figures: they were established with listeners who had healthy ears and were aged 18 to 25, which makes them a young reference ear rather than anyone in particular.
The sweep drops out in the middle.
A dropout at one point of the glide can mean a failing connection in one channel — an early broken wire. Wiggle the cable gently and replay to see if the symptom moves. On Bluetooth, interference and power saving can cause the same thing.
How is this different from the speaker test?
The speaker test checks the playback device's channels and output. This test diagnoses the worn state — orientation, stereo image, phase and bass. New headphones, or a familiar pair suddenly sounding odd, start here.
Is any audio recorded or sent?
No. Every tone is generated and played inside the page, the microphone is never used, and nothing is stored or transmitted.
Is the Headphone Test free, and do I need an app?
Free, with no account and no app. Headphone makers ship companion apps for their own models, and those are the wrong tool for this question anyway — a left-right swap or an inverted channel can come from the cable, the adapter, or the computer, none of which the maker's app can see.
Do I need special headphones for this to be worth doing?
No. Cheap earbuds show a swapped channel or a dropout in a frequency sweep just as clearly as expensive ones. What better headphones change is the bottom end: the deepest tones simply will not appear on small drivers, so treat a missing 40Hz as a fact about the hardware rather than a fault.