Device tests · Audio output
Left / Right Headphone Test
This headphone test sends a short tone to the left ear, the right ear or both, so you can check that stereo channels reach the correct side of your headphones, earbuds or headset. Put them on with L and R the right way round, lower the volume and press a button.
The automatic sequence plays Left, then Right, then Both, while the screen shows which ear should hear each tone. It takes about five seconds and needs no permissions.
- About 5 seconds
- L → R → Both sequence
- No permission needed
Headphone channels
Left
○ Silent
Both
○ Silent
Right
○ Silent
Nothing is playing.
Tones are generated locally in your browser. No microphone is used and nothing is recorded. The page knows which channel it sends, not what you actually hear; your answer stays on this page.
Your result
What your result means
Correct channels mean audio intended for the left reaches your left ear and vice versa. This matters for games, films and music mixed in stereo, and for spatial cues such as footsteps.
If the left tone arrives in your right ear while you are wearing the headphones correctly, the channels are swapped somewhere in the chain. If both ears hear every tone equally, mono audio is usually on. If one ear never hears anything, the problem is that side's driver, cable, connection or a balance setting.
- The on-screen indicator shows the channel the page sends — compare it with what you hear.
- “Both” should sound centred, as if coming from the middle of your head; a strongly off-centre Both suggests uneven balance or fit.
- A browser cannot tell whether a fault is in the driver, cable, adapter, Bluetooth link or settings.
Procedure
How the test works
- 01
Wear them correctly
Check the L and R markings and put the left side on your left ear.
- 02
Lower the volume
Set system volume low. Nothing plays until you press a button.
- 03
Run the sequence
Press Play L → R → Both and follow the indicator for each tone.
- 04
Report the result
Pick the option that matches what you heard to see local guidance.
Methodology
How Testpartout measures this
This describes exactly what the page's code does.
What the implementation does
- Audio starts only after a click, which creates or resumes a Web Audio AudioContext.
- A 440 Hz sine tone with 30 ms fades is routed through a gain node capped at about -18 dBFS into input 0 (left) or input 1 (right) of a two-channel ChannelMergerNode; Both feeds both inputs.
- The sequence plays Left, Right and Both for 1.2 seconds each, separated by half-second silences.
- Stop, route changes and page hide stop the tone at once, clear timers and close the audio context.
Limits of a browser measurement
- The page cannot hear your headphones, so the result relies on what you report.
- Mono audio, balance, spatial audio, headset apps and Bluetooth codecs can alter routing after the browser.
- This is not a hearing test or audiogram and makes no medical assessment.
Privacy
What happens to your data
This section describes the behaviour of the code on this page, not an intention.
- Tones are generated locally; no audio is downloaded, recorded or uploaded.
- No microphone access is requested, even for headsets with a mic.
- Your chosen result stays on this page and is never sent to analytics.
Troubleshooting
If the test does not behave as expected
Swapped left and right
Recheck L/R markings; some earbuds are easy to swap. Then look for a channel-swap toggle in the headset's companion app.
Both ears hear every tone
Turn off Mono audio in accessibility settings on Windows, macOS, iOS or Android.
One earbud silent
For true-wireless earbuds, return both to the case, close the lid, then reconnect. Some models default to single-earbud mode.
Wired headphones on one side
Push the plug fully in. A partially inserted 3.5 mm plug, a worn jack or an incompatible adapter can drop one channel.
Bluetooth headset sounds mono
When the headset mic is active, some systems switch to a lower-quality hands-free mode. Close call apps or pick the stereo output device.
Volume uneven
Centre the balance slider and check that ear tips are clean and sealed similarly on both sides.
Factors
What affects left/right routing on headphones
Routing can change at several points between the browser and your ears.
Wearing orientation
Wearing the headphones reversed swaps what each ear hears.
Mono audio
Accessibility mono mixing merges both channels into each ear.
Stereo balance
An off-centre balance slider weakens one side.
Spatial / surround effects
Virtualisation can make single-channel tones sound in both ears.
Adapters and connectors
Mismatched plugs (e.g. headset vs headphone jacks) may lose a channel.
Bluetooth profile
Hands-free headset mode may play mono audio.
FAQ
Frequently asked questions
- How do I test left and right headphones online?
- Lower the volume, wear the headphones with L on your left ear, and press Play L → R → Both. Each tone should reach the ear shown on screen.
- Why are my headphones' left and right swapped?
- Most often they are worn the wrong way round. Otherwise a headset app, audio driver or adapter may be swapping channels.
- Why does only one earbud play?
- The other earbud may be disconnected, in single-earbud mode, out of battery, or the balance may be set to one side. Reconnect both and check balance.
- Why do I hear the left tone in both ears?
- Mono audio is likely enabled, or a spatial audio effect is active. Turn them off and repeat the test.
- Can this test find which part of my headphones is broken?
- No. It confirms which channel the browser sends; it cannot tell whether a problem is in a driver, cable, adapter or setting.
- Is this a hearing test?
- No. It only checks stereo channel routing and does not measure or assess hearing.
- Does it work with Bluetooth earbuds and headsets?
- Yes, as long as they are the selected output device and playing in stereo mode.
- Is anything recorded?
- No. The microphone is never used, and your answer is not sent anywhere.
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