“…Already when the typically developed infant is between 3 and 5 months old, parents respond differently to infant vocalizations that are fully voiced and resonant than to vocalizations that are not fully voiced (Hsu, Fogel, & Cooper, 2000). Parents are able to confidently identify well-formed canonical syllables (combinations of consonant-like and vowel-like sounds with a smooth and rapid transition in between, e.g., "da") by the end of the first year (Oller, Eilers, & Basinger, 2001;Ramsdell, Oller, Buder, Ethington, & Chorna, 2012) and differentiate their responses to the child's vocalizations (Gros-Louis et al, 2006). Thus, it seems that parents, in the typical case, respond differently to more "mature" utterances, suggesting that parents also know how to discriminate between utterances at different levels (Gros-Louis et al, 2006).…”