Two things spring to mind with this right away.
1, do you have any parcels on your region? If so, it may eb a good idea to uncheck the option to 'restrict sound to this parcel' in the land options.
2, Your script (while would be ok in SL) is not good for opensim. Using llSleep in such a way is bad mojo (as WS would say
). What can happen is after 30 seconds of sleep the script thread can lock resulting in the script simply stopping working until it is recompiled.
It would be much better mojo to use a timer. Set the timer to 10 seconds, and use a vairable to increment each time to play the relevant sound. When the last sound is played, reset the variable to play the first sound again etc.
If you struggle with LSL, let me know and I will knock you something up that is much more opensim friendly