can you use the spell ghost sound to throw your voice so no one can tell where your location is?
Not exactly. But you can make a voice call out on one side of the room while your (invisible) on the other.
Unfortunately, there's a verbal component, so to pull this off you'd need Silent Spell.
what i am trying to do is have a big bad assassin taunt the party, he will be invisible but i want is for him to be able to talk with the party without them knowing where he is.
ah...what you want is Ventriloquism, Sorc/Wiz 1.
thanks, just looked at it that works exactly how i need it to
yeh, but then they get a bonus to their Perception check.