Stereo / Headphone Test
Test your headphones, earbuds, or speakers. Plays Left, Right, Both-channel tones plus a frequency sweep. Diagnoses dead drivers, wrong wiring, and balance issues.
30%
Start at 30% and increase gradually. Sustained high volume can damage cheap drivers and hearing.
What to listen for
✅ Left Only test
You should hear the tone ONLY in your left ear (or left speaker). If you hear it in your right ear, your headphones are wired in reverse or your audio source has channels swapped.
✅ Right Only test
You should hear the tone ONLY in your right ear. Same wiring check as above. If Left played in your left ear but Right plays silently, your right driver is dead.
✅ Both Channels
The tone should sound CENTERED — like it's coming from inside your head. If it sounds shifted to one side, your balance accessibility setting is off-center.
⚠️ Frequency Sweep
The tone glides from deep bass (50 Hz) to high treble (16 kHz) over 10 seconds. Listen for any sudden drop-outs in the sweep — a dead band indicates a damaged driver. Most adults stop hearing above 13-14 kHz; this is normal.
Troubleshooting common failures
- Both Left and Right play in the same ear: You have Mono Audio enabled. Disable it: iOS Settings > Accessibility > Audio/Visual > Mono Audio (OFF). Android: Settings > Accessibility > Sound > Mono audio (OFF).
- Left and Right are swapped: Common with cheap third-party Bluetooth earbuds. The earbud labeled L is acting as R. Try rebooting the earbuds (factory reset + re-pair); if that doesn't work, the firmware is shipped reversed and you'll need a replacement.
- One ear is much quieter: First, check your accessibility audio balance (iOS Settings > Accessibility > Audio Balance, recenter to 0). If still imbalanced, swap to wired headphones to isolate Bluetooth. If wired is also imbalanced, your hearing may be asymmetric (common with age and one-side phone use).
- Dead band in frequency sweep: A specific frequency range plays silent. Driver damage (often from a single high-volume burst like a video starting at 100% volume). Usually warranty-replaceable on premium headphones.
- Crackling during sweep: Bluetooth codec struggling at high frequencies — try switching to wired or to a higher-quality codec (LDAC, aptX HD, AAC) in your Bluetooth settings.
Frequently Asked Questions
What does the stereo test check?
Three things: (1) whether your left and right channels both work, (2) whether they are correctly wired (left audio comes out the left earpiece, not the right), and (3) the relative balance between them (one side noticeably quieter usually means a hardware fault). The frequency sweep also catches dead frequency ranges where a speaker driver has failed.
How do I know if my AirPods are balanced correctly?
Run the Left-Only test, then the Right-Only test. If both sound at roughly the same loudness when worn the same distance from each ear, your AirPods are balanced. iPhone has an additional balance fix: Settings > Accessibility > Audio/Visual > Balance slider. If one AirPod sounds quieter, try cleaning the mesh with a soft brush (earwax buildup) before suspecting hardware failure.
Why do both my earbuds play the same audio? It is not stereo.
Your audio source might be set to mono (one of: Settings > Accessibility > Mono Audio on iOS or Android; Windows Sound > Properties > Enhancements > Mono on PC). Stereo audio playing in mono sounds full but you cannot tell left from right. Disable Mono Audio in your accessibility settings, then re-run the Left and Right tests - you should hear them in different ears.
Why does only one earbud work, even though the test plays both?
Common causes: (1) one earbud is paired but its battery is dead (Bluetooth earbuds), (2) the earbud is dirty / clogged with earwax, (3) the audio source (your phone) has stereo balance shifted all the way to one side - check Settings > Accessibility > Audio Balance. (4) Hardware failure of one driver. Try the test with wired headphones to isolate Bluetooth from speaker issues.
What frequencies are good for testing?
Music covers roughly 20 Hz to 20 kHz. Most headphone drivers reproduce 50 Hz to 16 kHz well. The frequency sweep on this tool covers 50 Hz (deep bass) up to 16 kHz (cymbals/sibilance). Dead spots in this range indicate a damaged driver. People over 40 typically cannot hear above 13-14 kHz - this is normal age-related hearing loss, not a headphone fault.
Is this safe? Will it damage my hearing?
The tool defaults to 50% volume to limit volume to safe levels. If your system volume is already maxed out, you may want to lower it first. The frequency sweep includes both bass and treble - sustained high-volume bass can damage low-cost drivers, and sustained high-frequency tones above 12 kHz can be uncomfortable. Do not run the sweep at 100% volume for extended periods.
Does the test work on speakers or only headphones?
It works on any stereo output - headphones, earbuds, laptop speakers, external speakers, monitor speakers, soundbars, car stereos (if you can play web audio in your car). Stereo positioning is most obvious with headphones because each driver is dedicated to one ear; with speakers, the left/right distinction is muddier because both ears hear both speakers (just at different volumes).
What is mono vs stereo vs surround?
Mono: one channel - same audio comes from both speakers (or just one). Stereo: two channels - left and right are recorded separately, music is panned across the soundstage. Surround (5.1, 7.1, Dolby Atmos): multiple channels - center, front L/R, rear L/R, plus subwoofer. This tool tests STEREO. Surround test requires specific surround-formatted audio files and is out of scope for a browser tool.
Why is my left ear quieter than my right?
Possible causes in order of likelihood: (1) accessibility balance is off - check Settings > Accessibility > Audio Balance and recenter; (2) earwax buildup in one ear (real, not headphone issue) - try a different headphone, see if it persists; (3) earwax buildup in the headphone driver itself - gently clean with a soft brush; (4) age-related hearing loss is often asymmetric, especially if you favor one ear for phone calls; (5) hardware failure - usually wired into a warranty replacement.
Does this work on Bluetooth headphones?
Yes. The browser sends stereo audio to your default output device, including Bluetooth. Note: Bluetooth codec quality varies (SBC is the worst, AAC/aptX/LDAC are better) - lossy codecs may slightly compress the frequency sweep, but the left/right channel test is unaffected by codec choice.
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