Who's talking now? Infants' perception of vowels with infant vocal properties.

Little is known about infants' abilities to perceive and categorize their own speech sounds or vocalizations produced by other infants. In the present study, prebabbling infants were habituated to /i/ ("ee") or /a/ ("ah") vowels synthesized to simulate men, women, and children, and then were presented with new instances of the habituation vowel and a contrasting vowel on different trials, with all vowels simulating infant talkers. Infants showed greater recovery of interest to the contrasting vowel than to the habituation vowel, which demonstrates recognition of the habituation-vowel category when it was produced by an infant. A second experiment showed that encoding the vowel category and detecting the novel vowel required additional processing when infant vowels were included in the habituation set. Despite these added cognitive demands, infants demonstrated the ability to track vowel categories in a multitalker array that included infant talkers. These findings raise the possibility that young infants can categorize their own vocalizations, which has important implications for early vocal learning.