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Real Channel Detection

Stereo Separation & Phase Alignment Test

Checks whether your microphone actually provides two channels at the browser level — for the large majority of consumer mics and webcams, it does not, and this says so plainly rather than faking a stereo result. When genuine stereo input IS available, real phase correlation is measured between the two channels to catch problems that would cause cancellation when downmixed to mono.

Status

Click Start to check your microphone's actual channel count.

  • Channels detected:—

Result

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Phase Correlation
  • Verdict:—

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How to Interpret Your Results

What your channel count and correlation actually mean

Two separate things get reported here. First, your real channel count — most visitors will see "1 channel," which is the honest, expected result for almost any consumer microphone or webcam, not a fault. Second, if you do get 2 channels, a correlation score from -1 to 1 describing how closely your left and right channels agree.

Channel count: 1No stereo phase risk exists to test. Your device or OS is providing mono input, which is normal and will not cause the cancellation problems below.
Correlation above 0.7Well correlated — safe to downmix to mono without meaningful loss.
Correlation 0.2 to 0.7Genuine spatial separation, likely intentional from a stereo capsule design — usually fine, worth a listen to a mono downmix before relying on it.
Correlation -0.2 to 0.2Weak correlation. Left and right are capturing quite differently — check your mic's stereo mode if this is unexpected.
Correlation below -0.2Likely phase-inverted — will cause real cancellation in mono. Check for a swapped or miswired channel.

Benchmark Reference

Correlation Bands at a Glance

GradeCorrelationMono downmix outcome
Safe> 0.7No meaningful loss — channels agree closely.
Separated0.2 – 0.7Real stereo width, generally fine to downmix.
Weak-0.2 – 0.2Channels diverge — worth a listening check before relying on it.
Inverted< -0.2Real cancellation risk — audio will thin out or hollow in mono.

Applies only when a genuine 2-channel input is detected. Most visitors will see a mono result, where this table does not apply.

Step-by-Step

How to Run the Test

  1. Click "Start" and allow microphone access when prompted.
  2. Check your channel count first — if it reads 1, your result is complete and no further action is needed.
  3. If it reads 2, speak or make sound near the mic while watching the live correlation number update.
  4. Read your verdict and, if phase-inverted, check your interface or cable for a swapped channel.

Notes

Why most results say "mono"

Real stereo microphone capture — two independent channels reaching the browser — is genuinely uncommon outside dedicated field recorders and some professional USB interfaces. Even microphones marketed as having stereo capsules are frequently downmixed to mono by the OS or driver before any web page can see more than one channel. A mono result here is the honest, expected outcome for almost every visitor, not a sign of a problem.

Common Issues

Troubleshooting & Fixes

Microphone access blockedClick the camera/mic icon in your browser's address bar to confirm this site is allowed, or check your OS's microphone privacy settings if the browser already shows it as granted.
Expected stereo but got a mono resultCheck your microphone's own manufacturer software or OS-level input settings for a stereo or dual-mono capture mode — the browser can only request what the device and driver actually offer.
Correlation reads negative unexpectedlyA swapped or miswired XLR/TRS channel on a professional interface is the most common cause — check your cabling before assuming a mic fault.
Result changes a lot between runsBackground noise and where you're speaking from relative to each capsule both affect correlation — speak from a consistent position for a fair reading.

Common Questions

Frequently Asked Questions

Why does this say my microphone is mono when it has two capsules?
Most consumer webcams and USB microphones are downmixed to a single channel by the OS or driver well before the browser ever receives the stream, regardless of how many physical capsules exist. This is extremely common and does not indicate a problem with your hardware or this tool.
What does negative phase correlation mean?
It means your left and right channels are substantially out of phase with each other. Downmixing audio like this to mono — which most conferencing apps do — will cause real cancellation and a thin, hollow sound, since the two channels partially cancel each other out.
How do I get true stereo input from my microphone?
This depends entirely on your specific microphone and audio interface — check its manufacturer software or OS-level input settings for a stereo or dual-mono capture mode, since the browser can only request it, not force a device to provide it.
Does this send my audio anywhere?
No. All analysis runs locally in your browser using the Web Audio API — no audio is ever transmitted.
Is a mono microphone actually a problem?
No — mono is the standard, expected format for voice calls and most conferencing platforms downmix to mono regardless of what you send. Stereo only matters for music, ASMR, or field-recording use cases where spatial width is part of the content.