A left/right sound test plays a known signal through one stereo channel at a time. The left button should be heard on your left; the right button should be heard on your right. If both sides play together, check mono audio, spatial processing, and the selected output before assuming a speaker has failed.
Check your stereo channels. A few seconds is all it takes.
Ready to listen
Stereo speaker test
440 Hz · 8-second test
LIVE FREQUENCY SPECTRUMYour generated signal
20 Hz100 Hz1 kHz10 kHz20 kHz
Check speaker polarity
In-phase feels centered. Out-of-phase sounds wider or hollow.
Ready when you are. Choose a test to begin.
Headroom OK
Start with your device volume low. 50% here does not guarantee a safe listening level.
No sound, or only one side? Let’s troubleshoot +
Check the selected output in your system sound settings, unmute this tab, and reconnect your cable or Bluetooth device. Turn off mono audio to hear channel separation. Still unsure? Try another pair of headphones.
A SIMPLE START
How to run this audio check
01
Face your speakers
Sit in your normal listening position, or wear headphones with their L and R markings on the correct ears. Begin at low device volume.
02
Play each channel
Press Left speaker, then Right speaker. Note the physical source of each sound. Press Both speakers to compare the centered image.
03
Check an unexpected result
Turn off mono playback and optional virtual surround for a reference check. Reseat the connector, repeat the test, and compare another pair of headphones if available.
What correct stereo separation sounds like
Left and right are defined from the listener’s position. On headphones, the single-channel signal should be concentrated in the selected ear. On speakers, both ears naturally hear sound in the room, so listen for which speaker is producing it rather than expecting silence at the opposite ear. Keep your seating position consistent when comparing levels.
The test uses the same nominal tone for each side, making channel differences easier to notice than with music that deliberately places instruments off-center. Small perceived differences can come from room reflections, speaker placement, headphone fit, or hearing variation. This check cannot isolate those causes on its own.
Reversed channels, missing channels, and mono playback
If left plays on the right, first check physical labels and cable connections. Some adapters or routing settings can reverse the channels. If both buttons sound centered, inspect mono audio and any processing that combines or spreads channels. Changing the browser does not necessarily change your operating system’s output configuration.
For a silent side, lower the volume before reseating a plug. Compare the same headset on another source or another headset on the same source. That two-way comparison helps distinguish a device problem from the computer’s connection or settings. Do not raise the working channel to compensate for a silent one.
How the polarity check differs
The in-phase and out-of-phase buttons compare two relationships between the stereo signals. With speakers, an out-of-phase signal may sound diffuse or lose some low-frequency strength near the listening position. That is a listening clue, not proof that a particular cable is wired incorrectly; room acoustics and processing also matter.
Headphones keep the channels more acoustically separate, so their polarity effect differs from speakers sharing a room. Use the headphone page for balance and spatial comparisons. For six or eight physical output channels, use the surround test rather than treating stereo panning as a multichannel check.
What your result may mean
A listening clue is a starting point, not a diagnosis.
Common observations and practical next checks
What you notice
Possible explanation
Next check
Left plays from the right
Channel orientation or routing may be reversed.
Check speaker labels, headphone orientation, and cable routing.
Both buttons play both speakers
Mono mixing or output processing may combine channels.
Disable mono and repeat the same signal.
One side is much quieter
Balance, fit, connection, or hardware can affect level.
Center the balance and compare a second output device.
Sources & technical references
The tool behavior described here reflects this website’s implementation. These primary references explain relevant browser capabilities or equipment and application settings.
Face your speakers or wear the headphones correctly, lower the volume, and press Left speaker followed by Right speaker. Each signal should come from the matching side. Then press Both speakers and compare the centered sound. If separation is missing, check mono settings and the selected output.
Why does the left sound test play in both ears?+
Speakers naturally reach both ears through the room. On headphones, a left-only signal heard equally in both ears can indicate mono playback, crossfeed, or another processing setting. Check those options before blaming the headphones. The browser sends a channel signal but cannot override every downstream audio setting.
Does a stereo test prove my speakers have equal volume?+
It provides a repeatable signal for a listening comparison, not a calibrated acoustic measurement. Speaker distance, room reflections, headphone seal, and hearing differences can change perceived loudness. Keep position and volume consistent. If a difference follows the device across sources, investigate that device further.
Can I test wireless earbuds with these buttons?+
Yes, when the browser uses your earbuds as its output. Connect both earbuds, confirm their left and right positions, and play each channel. Check device balance and accessibility mono settings if separation is missing. Use the headphone page’s sync check if you also want to compare audible delay.