Vocal imitation is an essential component of early language acquisition in human infants. It occurs intensively during infancy, but is much less efficient later in life. A similar phenomenon occurs in songbirds: a zebra finch can accurately imitate a series of complex sounds during a sensitive period of its ontogeny, but as the bird grows up, it gradually loses the ability to imitate. It is now possible to record and analyze the entire vocal ontogeny of each bird (millions of sounds) and identify the emergence of each syllable type. We examine how individual syllables are learned by tracing trajectories of vocal change from the early subsong to the mature song. One can then examine how features of sounds changes to match a model, and how the order of sounds (syntax) changes during vocal learning until it matches the target syntax. Analyzing the entire vocal performance showed that vocal learning is strongly affected by night-sleep and by the age of the bird. The results raise some hypothesis about the function of brain mechanisms (e.g., song rehearsal during sleep) in natural behavior. We are now attempting to generalize our studies to integrate vocal learning analysis across behavioral, neural and vocal apparatus levels.