BACKGROUND CONDENSER MICROPHONE Boundary microphone. The PC Boundary is a very low-profile area microphone that can be used on any surface and with virtually any microphone mixer. With multiple polar patterns on board, three directional and one omni, the PC Boundary is ideal for any installation where premium area coverage and protection from RF/GSM interference is required. Easy switching between omni, cardioid, supercardioid or figure '8' polar patterns. Versatility for different acoustic environments. Consistent microphone voice across all four patterns. Easy to use mute switch, programmable for latching/off or momentary operation.