Private vs. Broadcast Speaker

What symbol(s) would you suggest to best (intuitive representation) indicate 2 different audio-speaker modes for a virtual receptionist controlling remote conversations with visitors standing at or near a kiosk? The 2 modes are "private" for 1:1 virtual conversations with a single visitor standing at the kiosk vs. "broadcast" for announcements to all visitors in the room containing the kiosk. TY!