Speaker Test: Check Left, Right and Stereo Sound
Play tones and voice cues on the left, right or both channels, sweep through frequencies, and check that your speakers are wired in phase.
Turn your system volume down before you press play, then raise it slowly. Test tones can be loud, especially the sweep and noise.
Channel
Polarity (both channels)
Level and pitch
Speakers fail quietly. A left and right swap after moving your desk, a tweeter that died months ago, a subwoofer wired backwards so the bass almost disappears. You rarely notice until a film sounds thin or a game’s footsteps come from the wrong side. This speaker test lets you check every part of the chain in a couple of minutes: each channel on its own, both together, a sweep across the whole range of human hearing, and a polarity check that reveals reversed wiring.
All sounds are generated live in your browser with the Web Audio API, so there are no files to download and no compression to colour the result. Each channel is fully isolated, which means when you choose Left only, not a trace of sound goes to the right.
How to test your speakers
- Turn your system volume down, then press Play. Raise the volume slowly until the tone is clear but comfortable.
- Choose Left only, then Right only. The matching speaker icon lights up. Each sound should come only from that speaker.
- Choose Alternate to hear the tone switch sides every second, a quick way to confirm left and right are not swapped.
- Switch the signal to Frequency sweep and listen as it climbs from 20 Hz to 20 kHz. Note any buzzing, rattling or sudden drops.
- Choose Both, play Noise, and toggle between In phase and Out of phase. The difference should be obvious.
What each test signal is for
Tone
A pure sine wave at the frequency you choose. Use the slider or the presets from 40 Hz to 12 kHz to check a specific range. Low tones test woofers and subwoofers, high tones test tweeters. A clean speaker reproduces a tone without buzzing or distortion.
Noise
Soft pink noise contains every frequency at once, balanced the way human hearing perceives loudness. It is the best signal for comparing left and right, finding the stereo centre and judging polarity, because it does not have a single pitch your ears can lock on to.
Frequency sweep
The tone glides smoothly from 20 Hz to 20 kHz over fourteen seconds and loops, with the current frequency shown live. It reveals rattles at particular frequencies, dead zones where a driver has failed, and the point where your speaker, and your hearing, run out of range.
Alternate mode
Alternate switches the tone between left and right every 1.2 seconds without you touching anything. It is the quickest way to check a setup from your listening chair, and handy when speakers sit far apart or behind a screen. If the sound seems to bounce between the wrong sides, or stays in one place, you have found your problem before you start rearranging cables.
Understanding the polarity test
When both speakers are wired correctly, their cones push and pull together. The sound fills the space between them and bass is full. If one speaker’s wires are reversed, the cones move in opposite directions, and low frequencies partly cancel each other out. The Out of phase option simulates exactly that by inverting the right channel.
Play noise with In phase, then switch to Out of phase. In phase should sound focused and centred with solid bass. Out of phase sounds diffuse, seems to come from everywhere, and loses its low end. If your speakers sound like the Out of phase setting even when In phase is selected, one of them is wired backwards. Swap the red and black wires on that speaker.
Reading your results
| What you hear | Likely cause |
|---|---|
| Left tone from the right speaker | Channels swapped at the cable or amplifier |
| Nothing from one side | Loose cable, balance setting or failed speaker |
| Silence above a certain pitch | Dead tweeter, or a normal hearing limit |
| Buzzing at some frequencies | Loose panel, worn cone or damaged driver |
| Thin bass with In phase | One speaker wired in reverse |
Most people hear up to around 15 to 17 kHz, and the upper limit falls with age. If the sweep goes silent near the top, that is usually your ears, not the speaker. The headphone test includes a dedicated high frequency range check.
Fixing common speaker problems
- Check the balance slider in your operating system sound settings. It is easy to knock it to one side.
- Reseat every cable, including the 3.5 mm jack, and try another port on the computer.
- Disable audio enhancements such as virtual surround or loudness when testing, since they alter the signal.
- Select the right output device in your system, particularly if a monitor or headset is also connected.
- Keep speakers away from walls if bass sounds boomy, and closer to them if it sounds weak.
- Angle speakers toward your ears so the tweeters point at your listening position, which sharpens the stereo image.
A complete audio check
Sound goes in both directions on calls and streams. After confirming your speakers, check your microphone level and recording, and your webcam picture. If your audio device is not listed or behaves oddly, the browser information tool shows whether Web Audio and media devices are supported in your browser.
Frequently asked questions
How do I test my left and right speakers?
Press Play, then choose Left only and Right only. Sound should come from only that speaker each time. Alternate switches sides every second for a quick check.
Why can I not hear the highest part of the sweep?
Most adults hear up to around 15 to 17 kHz, and the limit falls with age. Some small speakers also roll off before 20 kHz.
What does out of phase mean?
It means one speaker moves opposite to the other, usually because its wires are reversed. Bass cancels out and the sound becomes diffuse.
Can a speaker test damage my speakers?
Not at sensible volumes. Start low, avoid long loud tones at very low or very high frequencies, and stop if you hear distortion.
Does this work with Bluetooth speakers?
Yes. Any output your system is using will play the test signals, although Bluetooth adds a little delay. Many single-box Bluetooth speakers are mono, so left and right will sound the same.
How do I know if my speakers are wired correctly?
Play the left and right tests. If the sound comes from the wrong side, swap the cables. Use the polarity test to check phase.
Why does bass sound weak?
Small speakers cannot reproduce deep bass. Also check the polarity test, because reversed wiring cancels low frequencies.
What volume should I test at?
Start low and raise slowly until the sound is clear but comfortable.
Can I test surround sound?
This tool tests stereo left and right channels, which covers most computer and desk speaker setups.
Related tools
Speakers sound right. What about your headphones?
Check left and right, find your true balance point and discover the highest frequency you can still hear.