The positions of NAO’s four microphones are shown below.  Each microphone has a sensitivity of 20mV/Pa +/-3dB at 1KHz with a frequency range of 150Hz to 12kHz. The limitations to the microphone’s performance are the signal to noise ratio of the NAO’s environment, as well as any audio feedback the microphones might pick up on from its own motors and fans.  The goal is to have the video and audio as closely synchronized as possible (meaning existing latencies in both should match).  If the NAO’s audio quality is deemed insufficient, alternatives microphones may be sought after.