Robust knowledge of body part position and body pose enables more than just gross gesture recognition. It provides boot-strapping information for other methods to determine more detailed information about the user. Electronically steer-able phased array microphones can use the head position information to reject environmental noise. This provides the signal-to-noise gain necessary for remote microphones to be useful for speech recognition techniques . Active cameras can also take advantage of up-to-date information about body part position to make fine distinctions about facial expression, identity, or hand posture.