Sounds inside a subworld?

Subworlds again
I have this nice little subworld - a boatride, which works very well. To get it even more realistic I would like to have the water lapping-sound to be heard inside the subworld, and it doesn't... That water-lapping sound region works fine everywhere else, just don't when the avatar is inside the subworld.
Do I have to write that sound into the alscript for the boatride itself? If so, could someone point me to where I should 'place' that within the alscript, please? Or if not, what do I do?
Thanks.
Here's my current alscript:

Do I have to write that sound into the alscript for the boatride itself? If so, could someone point me to where I should 'place' that within the alscript, please? Or if not, what do I do?
Thanks.
Here's my current alscript: