[Freeswitch-users] conference with background sound

i like to setup conferences with some ambient music in the background. is there a background sound parameter? when i use the perpetual sound with local_stream its fine. but all the users have unmute themselve first. how can i to things with a user after he entered a conference? in the dialplan? via script? a more general question is how to play no-sound for certain events. if there is something like: <param name="kicked-sound" value="conference/conf-kicked.wav"/> can i set it to something like: <param name="kicked-sound" value="nosound"/> ?? t.