Babbling and Early Words

The early interpretation of similarities in the phonetic structure of babbling among infants who acquire different languages (e.g., Japanese, Hebrew) was that pre-speech vocalizations are universal. This observation was explained by the strong constraints of the mouth's anatomical characteristics and by physiological mechanisms controlling movements of the tongue and palate. Cross-linguistic research in the 1990s revealed, however, that clear influences of segmental and suprasegmental patterns (i.e., intonation and stress) of the input are recognizable in pre-speech vocalizations. This is particularly true during the second half of the first year of life. In a longitudinal comparative study by Bénédicte de Boysson-Baradis (1999) of ten-month-old Spanish, English, Japanese, and Swedish infants, the relative distribution of consonants in their canonical babbling resembled the distribution of these segments in their language. As babies grow, the segmental similarity between their babbling and early words increases. Several studies by Peter Jusezyk and colleagues on speech perception indicate that infants' sensitivity to the acoustics and phonetics of languages increases with age, influencing their ability to discriminate the sequences of sounds and syllable structures typical to their own language. Indirect evidence for the role of audition in the development of pre-speech vocalizations derives from studies on deaf children, who show significant delays in the emergence of canonical babbling and also a decreased variety of consonants uttered from age eight months onward.