At the risk of being obnoxious, I'm going to write again for the second time today: F1 (Help) is your friend.
From the DBP help under COMMANDS->SOUND:
LOOP SOUND
This command will play and loop the specified Sound Number continuously. Optional parameters allow you to specify a start position, end position and initial position in bytes that a looping sound will use as it plays.
SYNTAX
LOOP SOUND Sound Number
LOOP SOUND Sound Number,Start Position
LOOP SOUND Sound Number,Start Position,End Position
LOOP SOUND Sound Number,Start Position,End Position,Initial Position
RELATED INFO
SOUND Commands Menu
Index
EXAMPLE
View Showcase Example
View Usage Example
DBP + VC Ent.Studio | Maya, MAX, Soft3D, MilkShape, Character FX | 3.0Ghz P4, IC7G, GF 6800GT (primary) / 3200XP, A7N8x, GF 6600GT (secondary) / 6x dual 2.8Ghz Xeon SuperMicro (renderfarm)