What is stereo balance?

Stereo headphones play two separate channels, one for each ear. When both channels play the same sound at the same level, you hear it in the middle of your head. That is stereo balance. If one side is quieter, the sound drifts toward the louder ear, voices in music and films sit off-center, and in games it becomes harder to tell where sounds come from.

An imbalance can come from the headphones, such as a worn or mismatched driver, a damaged cable, or a blocked ear tip. It can also come from the fit, from the balance setting on your device, or from a difference in hearing between your ears. A test that plays exact, known levels to each ear shows whether the two sides match and which one is quieter.

Tool description

This tool plays test sounds, or an audio file of your own, to your left and right ears so you can check your headphones or earbuds. It measures how far off-center your balance is, checks that left and right are the right way round, and moves a sound smoothly from ear to ear. A meter shows the level each ear is getting as it plays.

Features

  • Balance test with a slider from 12 dB left to 12 dB right, in 0.5 dB steps
  • Compare both ears together, or left and right in turn
  • Random start, so you find the center by ear instead of stopping at 0
  • Result that names the quieter side and how much quieter it is
  • Left, center and right test to check that the channels aren't swapped and both sides work
  • Sweep that pans from ear to ear, with a sweep time from 2 to 20 seconds
  • Pink noise, white noise, or a tone from 125 Hz to 8000 Hz
  • Your own audio file, such as a song you know well, with a waveform to play, pause and seek
  • Live meter with the level of each ear in dB

How it works

The tool generates every sound in your browser with the Web Audio API, so nothing is downloaded or uploaded. An audio file you add also plays in your browser and never leaves your device. A single mono signal is split into the left and right channels, each with its own exact gain. In the balance test, moving the slider to the right turns the left side down, and moving it to the left turns the right side down, the same way the balance control on an amplifier works. When the sound seems centered, the side you moved the slider toward is the one that sounds quieter to you, by the number of dB shown.

Pink noise is the default sound because it spreads its energy across all frequencies the way music does, which makes the position of the sound easy to judge. When both ears play together, each side plays 3 dB lower so the pair sounds about as loud as one ear on its own. An audio file is mixed down to mono first, so instruments panned to one side in the recording don't pull the sound off-center, and it plays at its own level, which can be louder than the test sounds.

Tips

  • Set the balance slider in your device's sound settings to the center before you start, and turn off spatial audio or other sound effects.
  • Start at a low volume. Balance is easier to judge at a moderate level than a loud one, and it's safer for your hearing.
  • Test more than once with Random start. If your results are within 1 dB of each other, they are reliable.
  • To find out whether the headphones or your ears are the cause, test once, then put the headphones on the other way round and test again. If the quieter side swaps ears, it's the headphones. If it stays on the same ear, check the fit and the ear tips, or have your hearing checked.
  • A tone at a single frequency can show a driver that is only weaker at high or low frequencies. Try the balance test at 250 Hz, 1000 Hz and 4000 Hz.
  • For in-ear headphones, a better seal on one side makes that side louder and fuller in the bass. Reseat both earbuds before you test.