An analysis of the relative contributions of intrinsic, learned, and social factors in the acquisition of human speech. To determine the role of learned and social factors in speech acquisition, subjects were tested on a variety of auditory discriminations. The results demonstrate the existence of learning effects in the discrimination of auditory stimuli; however, these learning effects were found to be small (on the order of 15%). Moreover, these learning effects cannot account for the ability of most subjects to acquire speech within a few days or weeks. In addition, results obtained from adults without phonological memories and aphasic subjects indicate that knowledge of speech in the spoken language, learned social conventions, and learned phonological forms play a minor role in speech learning, compared to intrinsic properties of the speech signal. Although there is evidence that children acquire language-specific vocalization patterns in the normal fashion (i.e., as a reflex of the speech signal), the role of sociolinguistic and articulatory factors in language learning has to be considered more fundamental than previously assumed.