A soundfield system is, very simply, an amplification system which provides an even spread of sound around the room. That's the key it's a sound field. Not as we said like a PA system. Conversation should be at a natural, even sound level. We always say (I'm sure my colleagues will say something very similar) when you're using it as a teacher, you shouldn't really be aware that it's there. If you can hear it, it's set wrong, it's too loud. What you should notice, and you know that it's really working well then, is that you notice when it's gone.