Why can you hear everything in stereo, but something disappears in mono?
Two channels may contain a similar signal with opposite sign. When listening separately, both are audible, but when added, they are partially or completely subtracted. This is possible after stereo processing, mixing several recordings or changing the polarity of one channel.
The usual difference between stereo and mono does not in itself indicate a problem: the panorama and spatial effects should change. We are interested in a specific symptom - for example, the voice becomes very quiet or an important part of the bass disappears.
Check the fragment where the problem is heard
Select up to 60 seconds of recording. File limit - 8 MiB, one or two channels. The audio remains in the browser. You can start with two built-in examples: identical channels and their opposite polarity.
Audio mono compatibility test
FreeLoading the check...
Listen to the original stereo first, then mono. The volume is not automatically equalized: otherwise strong attenuation would be more difficult to notice. Switching maintains the current position while playback continues. Repeat the comparison on the problem area.
What do the indicators mean?
L/R correlation describes the similarity of decoded channels after subtracting their average values. A value of about +1 is typical for the same signal, about −1 for the opposite polarity. For complex stereo material, intermediate values are normal. If there is silence or no change in the signal, the indicator is not calculated.
Level in mono compares the average energy of the sum (L + R)/2 with the average energy of the original channels. This is not LUFS or a measure of perceived loudness. For example, a file with one full and one empty channel will produce approximately −3 dB using this formula; such a result does not in itself mean antiphase.
Suspicious areas observed over second windows: correlation below −0.3 together with attenuation greater than 6 dB or almost complete extinction. These are working listening guidelines and not a musician's standard of excellence. A very short problem may get lost inside the window.
How to choose your next action
| Result | What to check |
|---|---|
| One channel is almost empty | Recording input selection, routing and export to mono or stereo |
| Almost complete cancellation in mono | Channel polarity, duplicate tracks and their delay |
| The problem appeared after the stereo expander | Compare exports with and without processing at the same level |
| Average is normal, but voice disappears in places | Listen to the marked windows and a separate short export of the problem area |
| The file is already mono | Look for the reason for the change in sound in playback, processing or the source itself |
Don't blindly fix the entire file in one step
Inverting one channel can help a particular out-of-phase signal while ruining another part of the mix. First, find the source of the problem in your project: track, effect, or routing. Do a short re-export and compare it in the same way.
The analyzer does not change the record and does not restore missing data. It reads the parameters of the decoded audio at 48 kHz. Compression and decoding may change individual samples; readings should not be used as certification of original PCM, True Peak, or site compliance.
If the earphone is silent
Check several files. If the same side does not sound everywhere, use checking physical channels and material about one non-working earphone. If the defect occurs in only one recording, save a report of this file: it contains metrics and time sections, but not the audio itself.