BeHear SMARTO has three microphones (two in the hand-held device, and one in the supplied headset -- over-the-ear, or in-ear). They all are used to pick up the conversation.
The two embedded microphones in the hand-held device pick up sound and determine directionality, as well as serve to reduce environmental noise (including contact with the hand-held device by hands or clothes).
The microphone in the headset is used during mobile phone calls, as it is closest to the mouth. Therefore, during these calls there is no need to hold SMARTO in your hand. It can hang around your neck on the lanyard, be clipped to a pocket or purse, or placed on a nearby surface.