Insects can accurately navigate and track sound sources in complex environments using efficient methods based on highly appropriate sensory-motor processing systems. It is proposed here to describe, model and test these methods, by designing them for a micro-flying device. For this purpose, a new bio-mimetic acoustic sensor inspired by the cricket's auditory system was developed and tested. The sound sensor consists of two tiny omnidirectional microphones weighing only 0.1g, equipped with acoustic resonators and a biomimetic temporal processing system. The hearing system was tuned to the carrier frequency of the sound source, which is 4.7kHz (the frequency of crickets' song). The performances of the directional sound sensor were tested and described in terms of their linearity and accuracy, and their robustness to sound disturbances and dynamic sound source movements.