Check left and right speakers with a test tone

The job

Stereo sound only works when left really is left — swapped headphones, a miswired speaker, or a dead channel all fail the same way: music sounds wrong and game audio gives bad cues.

How to do it

Set a comfortable mid frequency — 440 Hz is fine — and a low volume. Choose "Left only", play, and confirm the sound comes from the left. Repeat with "Right only". If both sides play from both ears, the output is mono or the channels are merged.

• A tone that plays in one ear only can also mean the plug is not fully seated — reseat the connector before blaming the hardware.
• Use the sine wave; square and sawtooth add harmonics that make direction harder to place.

Also useful: frequency range

Sweep the frequency to sanity-check what your setup reproduces: laptop speakers fade below ~200 Hz, and hearing typically rolls off around 12–15 kHz for adults. A tone you cannot hear may be the speaker, not your ears — confirm on headphones.

Limits

The channel test needs stereo output — a single speaker or accessibility mono mode will always play both sides together. Extremely low or high tones may play silently without meaning the channel is broken.