Apple Logic Express 7 - Manual (Page 139)

Chapter 4 Audio in the Arrange Window 139
Delay
Just as with MIDI Regions, you can advance or delay the playback of Audio Regions, the
smallest available units being ticks.
The Region Anchor
The Anchor is an Audio Region’s temporal reference point. When you move an Audio
Region, it’s not the start point that is displayed in the help tag (as with MIDI Regions)—
it’s the Anchor point.
As an example, to guarantee perfect synchronization between a one-bar drum loop
and your MIDI Regions, the Anchor must be assigned to a well-defined musical point. If
the loop begins with a significant level peak (say a kick drum beat), set the Anchor to
the point where the volume of that beat is at its precise peak.
Any changes made to the position of the Anchor in the Audio window will directly
affect the corresponding Region in the Arrange window. The position of the audio will
shift in relation to Logic’s time axis, while the Anchor remains tied to the same bar
value, and is marked by a dotted line.