CheckMyBits

Speaker Test – Check Left and Right Audio

Check your left and right speakers separately, then both together. Turn your volume down a little first — the tone starts gently, but it is a pure tone and carries.

Which did you hear?

Runs in your browser. Nothing is recorded or uploaded.

How to use this speaker test

  1. Turn your volume down to about a third before starting.
  2. Put headphones on, or sit roughly between your speakers so you can tell the sides apart.
  3. Press Left channel. You should hear the tone only on your left.
  4. Press Right channel and check the other side.
  5. Use Frequency sweep to listen for buzzes, rattles or ranges that drop out.

What the results mean

Not working? Fix it

Windows 11 and Windows 10
  1. Open Settings → System → Sound and confirm the right output device is selected. Plugging in headphones switches this silently.
  2. Click the device → Balance and check both channels are at the same level. A balance knocked fully to one side is the most common cause of one-sided sound.
  3. Open the volume mixer and check this browser is not muted individually — per-app volume is easy to set by accident.
  4. Run Settings → System → Troubleshoot → Other troubleshooters → Audio, which resolves a good share of driver problems on its own.
  5. Disable audio enhancements: right-click the speaker icon → Sound settings → More sound settings, your device → Properties → Enhancements → Disable all.
macOS
  1. Open System Settings → Sound → Output and select the right device.
  2. Check the Balance slider on that screen is centred.
  3. Check Accessibility → Audio, where “Play stereo audio as mono” can be switched on and will mask a dead channel entirely.
  4. If sound is still missing, quit and relaunch Core Audio by restarting, or run sudo killall coreaudiod in Terminal.
iPhone and Android
  1. iPhone: check the ring/silent switch, then Settings → Accessibility → Audio/Visual for the balance slider and the Mono Audio toggle.
  2. Android: Settings → Accessibility for the same two settings, which exist under slightly different names by manufacturer.
  3. Disconnect Bluetooth devices — audio often continues routing to earbuds in a case or in another room.
  4. Clear the speaker grille. Pocket lint muffles phone speakers dramatically and is easy to miss.
Headphones and cables
  1. Push the plug fully in. A partly-inserted 3.5 mm plug very commonly gives one channel only.
  2. Wiggle the cable near the plug while a tone plays. Sound cutting in and out means the cable has failed there — the most common failure point on any headphone.
  3. Try the headphones on another device to establish whether the fault is the headphones or the computer.
  4. For USB-C headphones, check the adapter. Many are passive and will not work on phones that need an active one.
Bluetooth speakers and earbuds
  1. Forget the device and re-pair it. Stale pairings cause one-sided audio surprisingly often.
  2. Charge both earbuds. One flat earbud looks exactly like a dead channel.
  3. Move closer and away from microwaves, routers and USB 3 ports, all of which interfere with 2.4 GHz.
  4. Check whether your system has selected a "hands-free" or "headset" profile instead of stereo — that profile is mono and sounds noticeably worse.

Frequently asked questions

I only hear sound from one side. What is wrong?
Three usual causes, in order of likelihood. A balance control pushed fully to one side — check your operating system's sound settings, since this is easy to knock accidentally. A damaged cable, most often right where it meets the plug, which you can confirm by wiggling it while a tone plays. Or a plug not pushed fully into the socket, which commonly gives you one channel only.
Are the tones downloaded?
No. They are generated in your browser with the Web Audio API, so nothing is fetched and the frequency is exactly what is shown rather than whatever an audio file happened to encode. It also keeps the page small.
The left and right channels are swapped.
Usually headphones worn the wrong way round — the L and R markings are often small. If they are correct, some adapters and docks wire the channels incorrectly. Try the headphones in another device to work out which one is at fault.
What is the frequency sweep for?
It rises from 100 Hz to about 8,000 Hz so you can hear the whole usable range of most speakers. Listen for buzzing or rattling at particular pitches, which indicates a damaged driver or something loose in the enclosure, and for ranges that drop out entirely, which suggests a failing driver. It also gives a rough sense of your own hearing, though that needs a proper test to say anything meaningful.
I hear nothing at all.
Check the obvious first: system volume, the mute key, and whether the right output device is selected. Plugging in headphones or connecting over Bluetooth silently switches the output, and sound continuing to go to a disconnected device is a very common cause. The fix-it steps below cover each system.
The sound crackles or distorts.
Lower the volume slider first — distortion at high volume is often just the speaker being driven beyond what it can handle. If it persists at low volume, try a different cable or port. On Bluetooth, crackling usually means interference or distance rather than a fault; move closer and away from other 2.4 GHz devices.
Does this test my headphones too?
Yes, and headphones are the better way to run it — channel separation is far clearer than with speakers in a room, where sound from both reaches both ears. A dedicated headphone test with bass and stereo-imaging checks is planned.
Why does nothing happen when I press a button?
Browsers block audio until you interact with the page, which is why the test starts from a button rather than automatically. If the first press seems to do nothing, press it again — the first one may have been consumed unlocking audio.

Last updated 17 October 2026