How can I tell which speaker is left?

Sit facing the speakers and press Left. The speaker the chime comes from should be on your left-hand side. If it is on your right, the channels are swapped, usually by the cables.

What does a stereo test show that a left and right check does not?

The stereo test plays two tones at once, a low one on the left and a high one on the right. If each ear gets one tone, your system is keeping the channels apart. If both tones come from both sides, the sound is being mixed to mono somewhere along the way.

Why do I hear the left sound a little on the right side?

On speakers, both ears hear both speakers, so some spill is normal. On headphones, spatial audio, surround effects or a crossfeed feature can do this. Turn those off and test again. A browser test cannot measure how much leaks.

Can this page fix my balance or swap the channels?

No. It only plays sounds and shows what you matched by ear. To change anything, use your device's balance setting, swap the cables, or correct how you wear your headphones.

I only have one speaker. Can I run this test?

You can play the sounds, but Left and Right will come from the same place, so there is nothing to tell apart. That is normal for a single speaker. Plug in headphones to test the two channels of your device.

Left Right Audio Test

Find out which side is which. Play a chime on the left or the right, take a blind check that hides the answer, compare the balance one side at a time and hear whether your sound is in stereo or mono. It works by ear, so it cannot measure your equipment or your hearing.

Turn your device volume down before the first press, then raise it slowly. Keep it at a comfortable level.

Test volume: 25%

Left, right, both

Press a side to hear a short chime there. While another test plays below, these buttons move that test to the side you pick.

Blind check

Six rounds at random, with the lamps hidden. Say where you hear the chime, so what you see cannot steer what you hear.

Balance check

The same noise at the same level, one second per side. If one side sounds quieter, move the slider toward that side until they match.

Match the sides

LR

Sides level, nothing lowered

Mono or stereo

A low tone goes only to the left and a high tone only to the right, at the same time. In stereo each ear gets its own tone. If both tones come from both sides, the sound is being mixed to mono.

Nothing is playing.

All sounds are made in your browser. This page uses no microphone and records nothing.

How to run the left right sound test

Sit in the middle of your speakers, or put your headphones on by their L and R marks.

1
Press Left, then Right
Each press plays a chime on one channel. If it comes from that side, the channels are in the right order. The table below explains the other results.
2
Take the blind check
Knowing the answer can sway what you hear. The blind check plays six rounds at random, with the lamps hidden, and you say where each one came from. Then it gives you the result.
3
Check the balance and the stereo
Noise plays one second per side at the same level, and a slider lets you match them by ear. The last test plays a different tone on each side, which is the plainest way to hear mono against stereo.

To check everything else, use the Sound Test for speakers or the Headphone Test for bass and fit. To play your own tone on one channel, use the Tone Generator.

What it means when you press Left

The same reading works in reverse when you press Right.

What you hear	What it means	What to do
Only from the left	The channels are in the right order	Nothing
Only from the right	The sides are swapped	See the fixes below
Equally from both sides	The device is mixing to mono, or it has a single speaker	Check the mono setting. With one speaker, this test cannot go further
Mostly left, a little right	Normal on speakers in a room, or a sound effect is spreading the channels	Move closer to the middle, or turn off spatial effects
Nothing	No signal on that channel, or a fault on that side	Use the Sound Test or Headphone Test to narrow it down

Mono and stereo in plain words

Stereo means two separate audio channels, one for each side, and each can carry different sound. Sound seems to come from a direction because one side is louder than the other, or a little earlier. Mono means one channel: both sides play exactly the same thing.

Mono is not a fault. Windows and phones include a mono setting so you can hear everything through a single earbud, and plenty of voice recordings are mono from the start. But with mono switched on, Left and Right on this page will sound identical. On Windows 11 the switch is in Settings, Accessibility, Audio, and on Windows 10 in Settings, Ease of Access, Audio. On an iPhone, the balance slider is in Settings, Accessibility, Audio/Visual.

The slider here does not change your device. It only tells you how far apart the two sides sounded to you on this page, by ear and from where you are sitting. If you sit closer to one speaker, that speaker will seem louder without anything being wrong. A figure such as 3 dB is the slider's position and not a measurement. If you want to apply a correction, use your device's own balance setting.

If the left and right sides are swapped

Fix the cause you can reach first, then run the blind check again.

Headphones and earbuds
Look for the L and R marks and wear them that way. Earbuds are easy to mix up when the marks are small or worn off.
Stereo speakers
Swap the two speaker cables at the amplifier or computer, or simply swap the speakers' positions. Facing the speakers, left is on your left-hand side.
Phones and laptops
Built-in speakers cannot be rewired. Some phones with two speakers can change sides when you turn them, so test in the position you actually use.
Only in one app
If the sides are correct here and swapped in one video or game, the problem is that file or app, not your equipment.

When you need to know which side is which

Setting up desk speakers
Two identical speakers are easy to place backwards. A few seconds of chime confirms the setup before you fix the cables.
Earbuds with worn marks
Press Left with one bud in. If you hear it, that one is the left bud.
Checking a two-microphone recording
If each person was recorded on their own side, correct channels make it easy to know who is on which side when you listen.
Sound that seems lopsided
If a video always feels pulled to one side, the balance check tells you whether the same happens with an even test sound.

Your sound is sorted. What about your recordings?

Correct channels help when you review a recording by ear. ParrotNotes is for the recording itself: it records meetings and interviews, transcribes them and summarizes them.

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