Although speakers of one specific language share the same phoneme representations, their productions can differ. We propose to investigate the development of these differences in production , called idiosyncrasies, by using a Bayesian model of communication. Supposing that idiosyncrasies appear during the development of the motor system, we present two versions of the motor learning phase, both based on the guidance of an agent master: " a repetition model " where agents try to imitate the sounds produced by the master and " a communication model " where agents try to replicate the phonemes produced by the master. Our experimental results show that only the " communication model " provides production idiosyncrasies, suggesting that idiosyncrasies are a natural output of a motor learning process based on a communicative goal.