Left Right Speaker Test
Play each channel on its own to catch swapped wiring, a dead side, or a balance problem.
Ready
ReadyTurn your system volume down first
Start at a low volume, especially with headphones and low bass tones, then raise it slowly.
Press Esc to stop all sound · Shortcuts: L = left, R = right, S = stereo
This tool runs locally in your browser — no audio is uploaded.
How to use
- 1
Set up
Connect your speakers or headphones and set a moderate system volume. On a laptop, external speakers make the result easier to hear.
- 2
Play each channel
Press Left, then Right, then Stereo. Left and Right use different pitches so you can also tell them apart by ear. Auto runs the full sequence for you.
- 3
Read the result
Left should sound only from the left, Right only from the right, Stereo evenly from both. A silent side or swapped sides points to wiring, an adapter, or the OS balance slider.
How it works & limits
Each button synthesizes a steady sine tone locally with the Web Audio API and places it fully in one channel using a stereo panner: Left = pan −1, Right = pan +1, Stereo = both. If one channel is silent while Stereo works, your source and browser are fine — the issue sits in wiring, an adapter, or system balance.
Left plays 440 Hz and Right plays 587 Hz on purpose: if your channels are correct, the pitch also tells you which side is playing without looking at the screen. On mono devices (single laptop speaker, mono Bluetooth speaker) both tones collapse to one speaker, so a silent side there is a hardware design, not a fault.
FAQ
My left and right are swapped — what should I check?
Check the speaker wire colors and amplifier outputs first, then any 3.5 mm adapter or extension cable (some are wired backwards), then the operating system: on Windows, Sound settings → device properties → balance; on macOS, Audio MIDI Setup → configure speakers. If everything looks right, test another pair of headphones to isolate the fault.
Why is one side silent when I press Left or Right, but Stereo works?
Stereo working means both channels carry audio from the browser. When a single-channel tone is silent, the usual causes are a loose connector not fully inserted, a mono adapter, or the system balance slider shifted fully to one side.
My laptop has only one speaker — is it broken?
Many laptops mix left and right into one physical speaker. In that case Left and Right both play from the same place, which is normal. Use headphones to do a true channel check.
Can I use this with Bluetooth speakers or headphones?
Yes. Pair and connect first, then run the test. Note that some Bluetooth devices briefly drop the first tone after connecting — press the button again if the first playback is silent.
Does this test work on phones?
Yes, in any modern mobile browser. Phones have one speaker, so use wired or Bluetooth headphones for a real left/right check.
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