Speaker Balance Test

What is this tool?

The Speaker Balance Test pans one tone across nine fixed positions — 100% left, 75% left, 50% left, 25% left, centre, 25% right, 50% right, 75% right, 100% right — so you can hear whether the image moves smoothly and sits where it should.

Around that ladder it adds a channel separation listening test, a left/right identification exercise, and frequency balance checks at fixed points from 100 Hz to 10 kHz. The guided paths are a six-step quick balance test and a thirteen-step full test.

Balance problems are unusually easy to live with unnoticed: your brain compensates for a mild offset within minutes. A deliberate pan ladder is what makes the offset audible again.

How to use it

1. Sit centred and equidistantBalance is a geometry question before it is an audio question. Sit the same distance from both speakers, facing forward, before you judge anything — and for headphones, check that left and right are actually on the correct ears.
2. Start at centreA centred tone should appear to come from directly in front of you (or from the middle of your head, on headphones). If centre already pulls to one side, everything after it will be misread, so fix this first.
3. Walk the nine-position stepperMove from 100% left to 100% right one step at a time. The image should travel evenly, with 25% and 75% clearly distinguishable from centre and from the extremes. Uneven jumps are what you are listening for.
4. Check the extremes for separationAt 100% left, the right speaker should be silent, and vice versa. Anything audible on the opposite side is crosstalk, a mono downmix, or a spatial-audio effect adding it back.
5. Repeat at several frequenciesRun the balance checks at low, mid and high frequencies. Balance can be correct at 1 kHz and wrong at 100 Hz, which usually means the difference is in the drivers rather than in a level setting.
6. Try the identification exerciseThe tool plays a channel and asks which side it came from. Getting this wrong consistently is the fastest way to discover swapped channels — more reliable than looking at the cables.

What the results mean

Centre is not centred

If the centre position pulls left or right, something is offset. In order of likelihood: an OS or app balance slider that is not at zero, a volume difference between two separately powered speakers, a seating position that is not central, or a genuinely weaker driver.

The image moves unevenly

Steps should feel roughly equal. If the tone jumps from centre straight to one side and the intermediate positions are hard to tell apart, one channel is quieter, and the pan is having to work against that offset.

Sound on both sides at a full extreme

At 100% left, hearing anything on the right means the channels are not fully separated. Common causes are a mono downmix, a spatial-audio or virtual-surround effect, an unbalanced cable picking up crosstalk, or simply room reflections — speakers in a small room always bounce sound to the other ear.

Balance correct at one frequency and wrong at another

A level difference is frequency-independent; a driver problem is not. If left and right match at 1 kHz but diverge at 100 Hz or 10 kHz, look at the hardware rather than at a balance slider.

The sides are swapped

If the identification exercise consistently disagrees with you, left and right are reversed somewhere — the cables, the headphone orientation, or a channel-swap setting. It is one of the most common findings here and one of the easiest to fix.

What it can detect

• A left/right level offset, including one small enough that you had stopped noticing it
• Swapped channels in cables, headphones or system settings
• Poor channel separation, including mono downmixing and virtual-surround effects
• Imbalance that appears only in part of the frequency range
• A speaker or driver producing noticeably less output than its pair

Limits worth knowing

A browser can only report what the platform gives it. These are the honest boundaries of this page, so a result is never read as more than it is.

• It cannot measure loudness. There is no microphone in this tool, so it cannot report SPL, cannot say how many decibels apart your channels are, and cannot confirm a defective speaker — the page's “WHAT THIS TEST CAN & CANNOT MEASURE” section and its SPL and “diagnose a defective speaker” FAQs say the same.
• The panning happens digitally in a StereoPannerNode before the signal leaves the browser, so what you hear is that digital pan combined with everything downstream: OS balance, per-app volume, spatial audio, the amplifier, and the two drivers.
• Room acoustics genuinely change the answer. Speakers in an asymmetric room — one near a wall, one in open space — will not sound balanced even when they are electrically identical. Headphones remove that variable, which is why they are the better reference here.
• Your own hearing is part of the measurement. A mild asymmetry between your ears will read as a speaker imbalance, and this tool has no way to tell the two apart.

Tips

• Verify with headphones before you adjust anything. If the balance is correct on headphones but wrong on speakers, the problem is the speakers or the room, not the computer.
• Swap the two speakers physically — left to right — and retest. If the weakness moves with the speaker it is hardware; if it stays on the same side it is the channel, the cable or a setting.
• Check your OS balance slider before assuming a fault. An accidentally nudged balance control is the single most common explanation for an off-centre image.

Troubleshooting

Related documentation

• AudioLeft Right Audio TestThe quickest way to prove which side is which, with a blind identification game.
• AudioStereo TestChannel isolation, balance, separation and phase checks for any stereo setup.
• AudioSpeaker TestLeft, right, stereo, bass, treble and sweep tones for laptop or desktop speakers.
• AudioHeadphone TestEars, balance, separation, bass and treble checks built for headphones and earbuds.
• AudioAudio Bass Test20 Hz to 250 Hz tones for sub-bass reach, rattle hunting and distortion checks.