I've asked around and troubleshooted this with a couple people in IRC and we've found nothing. My assumption is that it may only be possible in patch 1.2 where you can make actors work for certain players only? My sounds are global too and it's annoying.
Yeah I mean it seems like it should be so obvious. I need to spend longer trying to figure it out, but so far examining Sound actors, Events on actors, and the Sound data objects themselves has yielded nothing.
Woops totally misread your post. I thought you were playing a sound in the events of an actor ... not using a sound actor. My problem is the using the play sound message on an actor. Sorry for not helping :(