Learning to speak. Sensori-motor control of speech movements

Abstract This paper shows how an articulatory model, able to produce acoustic signals from articulatory motion, can learn to speak i.e. coordinate its movements in such a way that it utters meaningful sequences of sounds belonging to a given language. This complex learning procedure is accomplished in four major steps: (a) a babbling phase, where the device builds up a model of the forward transforms i.e. the articulatory-to-audio-visual mapping; (b) an imitation stage, where it tries to reproduce a limited set of sound sequences by audio-visual-to-articulatory inversion; (c) a “shaping” stage, where phonemes are associated with the most efficient available sensori-motor representation; and finally, (d) a “rhythmic” phase, where it learns the appropriate coordination of the activations of these sensori-motor targets.