Open Audacity and select "File" and "Import" from the top menu. Select and open the file, in MP3 format, that you wish to import. Wait for the file to import into the software.
Click the down arrow, located on the "Track Pane" window to the left of the song. Select the "Split Stereo Track" option from the drop down list. Another track titled "R" will be listed below the original track.
Highlight the "R" track and click "Effects" from the top menu. Select the "Invert" option from the drop down menu. Mute both of the tracks by selecting the "Mute" option from each "Track Pane" window.
Click the "Play" button to preview the acapella track.
Open Sonar and click "File" and "Import File" from the top menu. Select the location of the file and click the "ok" button at the bottom of the window. Wait as the song loads.
Right click the song and select the "Split Stereo Track" option from the side menu. There will be a track titled "R" below the original song.
Right-click the "R" track and select "Effects" from the side pop up menu. Select the "Invert" option and wait as the effect is applied. Click the "Play" button from the "Transport" window at the top of the screen to preview the acapella track.