The difference between stereo and mono WAV files (essential knowledge)

David Mellor

David Mellor is CEO and Course Director of Audio Masterclass. David has designed courses in audio education and training since 1986 and is the publisher and principal writer of Record-Producer.com.

Monday July 22, 2019
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There's more of a difference than you might think.

I'll keep this short, but it is important.

There is something else to know about the mono file and that is that most playback software and systems will automatically pan the one channel center, which means that it is sent equally to the left and right outputs, and so therefore to the left and right loudspeakers or sides of the listener's headphones or earbuds.

But there is another type of file, which is a stereo file in which both channels are identical.

So there are two channels, but each has the same audio content.

When played back the result is mono, and there is no audible difference between this and a normal single-channel mono file.

The problem

The problem comes when you send a 2-channel mono file to someone else, perhaps as part of a larger project, or perhaps as a finished product ready to be prepared for market.

The person who receives the file will listen to it and say, "Hey - this is mono!" Or at least think that.

Without any further information the likely next assumption is that there has been an error and that the file should contain stereo audio. A stereo file with mono content - how can that not be an error?

Well often it can be correct. Some DAW softwares don't have the option to bounce to mono, and some others don't make the option obvious. So the user bounces a mono recording - perhaps a simple recording of speech - to a stereo file.

(It's worth noting that even a single person speaking can be recorded in stereo to capture stereo ambience.)

Worse still...

We hear all kinds of problems here at Audio Masterclass, and we're here to help.

Another problem with a stereo file containing a mono recording is that instead of the audio being identical on both channels, it is only on the left or only on the right channel.

Once again, anyone who receives this file will have doubts, this time about what perhaps should have been on the other channel.

Without further information, it seems as though there is a fault, and problems like this either slow down the production process or lead to other problems being created. At worst in the professional working environment, the person who caused the problem could be disciplined or fired.

The solution

The solution to these potential problems is to be sure to create a mono file if the material is mono.

If your DAW doesn't allow you to bounce to mono, then bounce to a stereo file and use a utility to split it into two mono files, then delete one of them. You'll find information suitable for your needs through a simple web search.

One more thing...

I've talked about mono WAV files and stereo WAV files, but there is another type of file that is occasionally relevant...

This is the 2-channel WAV file that is not stereo.

Think of it as a multitrack recording, but with only two tracks.

So you could have a dialog between two actors or voice artists and pan one hard left and the other hard right, as source material to manipulate further down the line in the production process.

Conclusion

The difference between mono, stereo and two-track WAV files is important. Get it right and the production process will be smooth. Get it wrong and there may be problems that take time and perhaps money to resolve.

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