If you set loop=true, the sound will be reproduced again once the loop-time is finished. The loop-time in SECONDS is the time until sound plays again.
IMPORTANT: You are free to add as few seconds as you want, but it could have an unwanted server cost. My recommendation of using this loop feature is to allow the loop for songs with more than 50 or 60 seconds. And finally, know the duration of your sound in seconds to correctly add it to the region's loop-time property, then you will have your sound playing again at the end of the current play.