I would like to separate a mp3 file according to that it has different sounds played by my left and right speakers. So I am reading this link http://b27.cc.trincoll.edu/weblogs/sta/2010/05/how_to_extract_instrumental_version_of_a_song_audacity.html

First of all open the song. File --> Open

Next, you want to split the track into two channels. Click on the song title bar (on the left hand side). Click on the title bar and then select "Split Stereo Track."

Now two separate channels for the song will be displayed. Highlight any one of the two tracks, then go to Effect --> Invert.

What are the definitions of a track and a channel? I have googled them, but surprisingly can't find them.

Are they defined for different things?

How are tracks and channels related?


  • I don't understand what your goal is? are you trying to extract the centre channel?
    – n00dles
    Commented Jun 24, 2015 at 12:49
  • It is a mp3 for Karaoke. The sound played by my left speaker is the accompaniment, while the sound by my right speaker is the whole song with the singer's voice. I want to extract the former sound.
    – Tim
    Commented Jun 24, 2015 at 13:35
  • So you want just the vocals?
    – n00dles
    Commented Jun 24, 2015 at 15:31
  • no. the accompaniment
    – Tim
    Commented Jun 24, 2015 at 15:33
  • I think you're asking the wrong question ;) Also you're on the wrong Audacity help page. If your 'song' has instrumental on the left & instrumental+vocals on the right & what you need is just the instrumental; then the function you need is along the lines of "split stereo tracks to mono". This will give you two separate tracks , each containing one mono channel. Your current file is one stereo track, with 2 channels [Left & Right]
    – Tetsujin
    Commented Jun 25, 2015 at 8:54

2 Answers 2


Basically, a 'channel' is an audio signal and a 'track' is where they can be written/read.

In recording studios, before the digital revolution, multitrack tape was used to record single channels of audio onto separate tracks.

Multitrack recording software now has the capability of creating an unlimited number of tracks, and for each track, you can have numerous channels.

The current standards are:

     Mono(1 channel)
     Stereo(2 channels)
     2.1(3 channels)
     5.1(6 channels)
     7.1(8 channels)

 Note the '.1' refers to a LFE(Low Frequency Effects) Channel. So 5.1 would be 
 5 x Full frequency channels and 1 x Low frequency channel.

Each of these could be assigned to a single track in most modern multitrack audio recording software.

  • When multiple channels are recorded in one track, are the signals from different channels separately stored or not in the track?
    – Tim
    Commented Jun 26, 2015 at 21:29
  • I don't get what you mean. I think you need to get some literature on basic multitrack or digital audio recording. I think it will help you with a few things. Maybe somebody could recommend some reading if you ask :]
    – n00dles
    Commented Jun 27, 2015 at 5:08
  • 1
    are the signals stored on a track mixed into one signal or still separate?
    – Tim
    Commented Jun 27, 2015 at 10:58
  • It depends on the track - You can't put a stereo recording on a mono track - the signals would need to be added together, or left or right selected. Most modern DAWs will automatically create the right type of track with the right number of channels if you drag-and-drop or import an audio file.
    – n00dles
    Commented Sep 3, 2023 at 18:05

What you are interested in here, is the side material, or the difference between left and right (i.e. when these don't play the same).

Typically vocals are mixed equally loud in left and right channel (the vocal is in "center"), but the accompaniment is spread out differenty across left and right side (or channel).

To get that difference you need to get one side to cancel out the other, and the easiest way to do that is to simply pahse invert one channel. But you can't do that with a stereo file, so you need to split it first into two separate tracks (or files), and then flip/inverse/invert just one of the tracks.

You may hear other things like the kick and bass disappearing too, so what you can do is to mix in a bit of the mono low end.

  • Thanks. What is " pahse invert "? Why can't I 'do that with a stereo file"?
    – Tim
    Commented Jun 27, 2015 at 0:04

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