Playback and Recording : Playing Back Track Material : Playback Modes : Loop Playback Mode

Loop Playback Mode
When Loop Playback mode is enabled, the selected track range repeats on playback. If there is no selection, playback occurs normally from the current Cursor location.
*
A selection must be at least 500 ms in length for it to loop on playback.
Looping playback is a useful way to check the rhythmic continuity of a selection when working with musical material. If you’re working with one-bar selections, you can loop playback to see if the material loops cleanly. If it seems to skip, you should then adjust the length of the selection until it works “musically” within the context of the playlist and the other tracks.
To loop playback of a selection:
1 Select Options > Link Timeline and Edit Selection.
2 With the Selector tool, select the track range you want to loop.
3 Enable Loop Playback by doing one of the following:
*   
Select Options > Loop Playback.
*   
Right-click the Play button in the Transport window and select Loop from the pop-up menu.
*   
Control-click (Mac) or Start-click (Windows) the Play button in the Transport window.
*   
Press Command+Shift+L (Mac) or Control+Shift+L (Windows).
*   
With the Numeric Keypad mode set to Transport, press 4 on the numeric keypad.
When enabled, a loop symbol appears in the Play button in the Transport window.
 
4 Click Play in the Transport window.
Playback begins from the pre-roll point (if enabled) and continues to the selection’s end point, where it loops back to the selection’s start point.
5 Click Stop in the Transport window to stop playback.
Loop Playback and Audio Recording
Looping playback does not enable loop recording. Use Loop Record mode to loop during recording (see Loop Recording Audio).