YouTube Audio Channel Checker: find one-sided or out-of-phase audio

If viewers hear your voice in only one ear, the microphone was recorded on one side of a stereo track. Drop your video or audio file here: the tool compares the left and right channels where there is sound, tells you if the audio is balanced, one-sided, out of phase or fake stereo, shows the worst moments, and explains how to fix it in OBS, Premiere Pro or DaVinci Resolve.

Updated October 19, 2026 · Built by Kevin Tabares, long-form YouTube editor at Umbrella Creators.

Check the left and right channels Choose a video or audio file or drop it here · MP4, MOV, MKV, WEBM, MP3, WAV, M4A · up to 60 minutes

Your file stays on your device. Nothing is uploaded: your browser reads the audio and measures both channels right here, in this tab.

How to use it

Choose your finished video, the raw recording or just its audio (MP4, MOV, MKV, WEBM, MP3, WAV or M4A).
The tool skips the silent parts and measures every 50 ms where there is sound: how loud the left and right channels are, and how much they move together.
Read the verdict, look at the strip for the moments where one side takes over, and click any moment to hear it. Use headphones to hear the difference.

Very big files can be too much for a browser tab, because the whole audio is decoded in memory. If that happens, export just the audio as M4A, MP3 or WAV and check that: the result is the same.

What the results mean

Result	Reading	What it means
Balanced	under 1.5 dB	Both sides are about as loud. This is what you want for a voice.
Leaning	1.5–6 dB	One side is louder. On headphones the voice sits off center.
One-sided	over 6 dB, or one side silent	The voice is only (or almost only) in one ear. Fix it before you upload.
Normal phase	correlation above 0.3	The two sides move together. A voice usually reads above 0.9.
Wide stereo	correlation 0 to 0.3	The two sides are different, typical of stereo music or ambience. Fine, as long as the voice is in the middle.
Very wide	correlation -0.3 to 0	Part of the sound can cancel on a phone. Listen to it in mono.
Out of phase	correlation below -0.3	One side is inverted. In mono the voice gets much quieter or disappears.
Fake stereo	correlation above 0.999 and under 0.1 dB apart	Both sides are identical: a mono recording copied to two channels. Fine for voice.

Balance is the median difference between the left and right level over all the moments with sound. Correlation goes from 1 (both sides identical) to -1 (one side is the other one inverted). The mono change is how much louder or quieter the audio gets when a phone adds both sides together: a centered voice changes by 0 dB, a voice on one side drops about 6 dB, and an out-of-phase voice can almost vanish.

FAQ

Why is my voice only in one ear on YouTube?

Almost always because the microphone was recorded into one side of a stereo track. A mono mic plugged into input 1 of a two input audio interface, or captured as a stereo source in OBS, lands only on the left channel; input 2 lands on the right. YouTube plays the two channels as you upload them, so viewers with headphones hear the voice in one ear. Make the mic mono in OBS before you record, or send the good channel to both sides in your editor.

Does YouTube fix mono audio?

YouTube does not move a one-sided voice to the middle: it plays the left and right channels you give it. A true mono file (one channel) plays in both ears, and so does a stereo file with the same sound on both sides. The problem is only a stereo file with the sound on one side, or two sides that cancel each other.

What is out of phase audio?

It means the left channel is the right channel turned upside down (or close to it). On headphones it sounds wide and strange; on a phone speaker or any mono device the two sides are added together and cancel, so the voice gets very quiet or disappears. It usually comes from a wrongly wired cable, a polarity switch, or a stereo effect. The safe fix is to keep only one of the two channels.

Should YouTube videos be stereo or mono?

Upload stereo, with the voice in the middle (the same on both sides). Music and sound effects can use the full stereo width, but the voice should not lean to one side. Many viewers watch on phones that play in mono, so the mix should still sound right when both sides are added together.

Does this tool upload my file?

No. Your browser decodes the audio and measures it on your own device. The file never leaves this tab and nothing is saved.

Who made this

I'm Kevin Tabares. I've edited long-form YouTube videos since 2015 (1,277 videos and 152.2M+ views tracked on YT Jobs) for channels like Rex & Alexa, Puff and Mud. Making sure the voice sits in the middle and survives on a phone speaker is part of every edit I do; I built this so you can check your own file in seconds before you upload. If you want an editor for your channel, get in touch.

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