Demystifying Stereo and Mono
Because of the way Audacity treats individual tracks, it is easy to get confused about the difference between stereo and mono projects. First, a quick review on nomenclature in Audacity.
Tracks - Tracks are individual pieces of audio. They can be either stereo or mono.
Channel - Channels refer to either the right (R) or left (L) speaker.
Stereo - Stereo refers to a track where there are two channels that are distinctly different. It will appear as one track, but with two waveforms in it.
Mono - Where a single track is distributed to both channels.
The confusion comes in realizing that, in Audacity, each track can be specified to either the left channel, right channel, mono or placed in a stereo-pair.
The next few sections will take you through a few different scenarios.
Changing mono tracks to output audio in mono
To change these settings, click the drop-down menu at the top of each track (where the track name is).
Most interviews are done with a single mono microphone. In these cases, you almost always want to use the mono setting for each track. Setting the mono option on each track will ensure that the audio is distributed evenly to both channels. If the track is set to either the right or left channel, you will hear it come out of only one side during playback. If you notice this, set the track to mono.
Changing stereo tracks to mono tracks
Some digital audio recorders have stereo microphones and will record two tracks of audio as a stereo-pair. You will know you have this situation if you import your audio and you see a single track, but with two waveforms, as in the image below.
Notice that the above image is one track of audio, despite the track having two distinct waveforms. This is called a stereo pair, and each of the waveforms is on a different channel (the top waveform is the left channel). You cannot edit these channels individually. Any adjustments you make will be done to both channels equally, including when you adjust the sound envelope or cut the track during editing.
You first have to decide if you want your project to be a stereo project or mono project. A stereo project might sound a little more realistic because it mimics how sound is interpreted in real-life. However, the sound file will be twice as large and that can cause slow loading speeds on the Internet.
Most serious journalistic radio organizations only use mono tracks. Stereo can interfere with the way the story is perceived or be a distraction. Although, in some cases, it can also add dimension to a project that puts the listener "right there." This choice is a subjective one, sometimes even an ethical one. For general purposes, we recommend doing journalistic audio pieces in mono.
There are two methods to convert a stereo track to a mono track.
Method 1) Splitting the stereo track and deleting one of the channels
To split the stereo track, click on the drop-down menu above the track and select split stereo track.
This will split the channels into individual tracks. Once you have two tracks, you can simply delete the track you do not want by clicking the close "X" button.
Method 2) Merging the two channels of a stereo track into one track (preferred)
If you feel that you might need audio from both channels, then you can merge both channels into one. This could occur if you recorded an interview in stereo, and one person might have been closer to one side of the recorder and might sound louder on one channel.
Combining the channels ensures that sounds in both channels will be equally represented in the track.
To convert, click on the track you want to combine, and from the track menu, select Stereo Track to Mono.
There might be some slight quality loss in combining the channels, although if there is, it would only be very slight.