place a sound trigger down, right click it, on the left is a list of scripts names look for "main" to the right of that click the "...." this will bring up a list of scripts for use, find and select "plrinzone" now further down the list on the left find the place for the sound you want played and put the sound link in, away you go the sound will play (abit rough for a guide sorry).
hope it helps for you though.
if you know anything about Lua or scripting you can edit (back ups that is) or add Lua scripts from the script bank to make sounds loop for example. I have been toying around with it but not to any success as yet.
have fun stay safe
hood