Loop Play Back Mode
In some cases, you might want to play a section of audio over and over.  For example, if you are practicing a part before recording or adjusting effects on a section, you might want to loop a selected area of audio.  

This should not be confused with looping sounds, though.

To loop an area of the project, make a selection as shown below.



Now click the Loop Play Back Mode icon on the Master Bar and it will become high-lighted . Click the Play button and it will loop the selected area.  Each time you stop play back, the loop selection area will be reset to the current selection (If there is no selection, it will loop the entire project.)

To turn off Loop Play Back Mode, click the Loop Play Back Mode icon again  .

Alternatively, you can select the Mix menu and select Loop Playback Mode to set the looping area.

(This should not be confused with looping sounds.)