Patterns of onset of canonical babbling among typically developing infants

Date of Award




Degree Name

Doctor of Philosophy (Ph.D.)

First Committee Member

D. Kimbrough Oller, Committee Chair


The onset of canonical babbling (production of mature, speech-like syllables) is an important vocal developmental milestone as infants cannot begin to produce meaningful speech until they can consistently produce these syllables (Oller, 1978; Stoel-Gammon & Cooper, 1984). Certain groups of infants who are at risk for language delays (i.e. hearing-impairment) demonstrate reliably later onsets of canonical babbling (Eilers & Oller, 1993; Stoel-Gammon & Cooper, 1986). What is not known, however, is whether the onset patterns of canonical babbling in infants who are at risk for later language delays differ from the onset patterns in typically developing infants. To lay the groundwork for such comparisons, the present study evaluated the vocalization patterns of typically developing infants during the one-month period following the designated onset of canonical babbling. Analyses indicated that the infants demonstrated a small, but reliable increase in their production of canonical syllables from the pre-canonical samples to the post-canonical samples (as indicated by the canonical babbling ratios). Modifying the definition of the canonical syllable to disinclude glide elements appeared to help clarify the stage differentiation. Results indicated that number of both single canonical syllables and reduplicated syllables were reliably different between pre- and post-canonical sessions. Results also suggested that marginal babbling ratios may decrease following the onset of canonical babbling. Although the infants demonstrated tremendous variability in their amount of canonical syllables produced across sessions, a criterion ratio of.10 may be a useful compromise in determining if an infant is in the canonical stage of vocal development while minimizing the number of false positives and false negative. A previous study (Oller, Eilers, & Steffens, 1993) indicated that canonical babbling ratios gradually increase over several months following onset, but in the present study, no noticeable increase was observed across the initial month following onset. More distinct stage differentiation and clearer increases in canonical babbling ratios across the month may have been observed had the study included sampling for longer periods of time, or at closer intervals. These results provide some support for the stage theory of prelinguistic vocalization development, but indicate that changes in sampling methodology may be needed to further clarify the nature of onset of canonical babbling.


Language, Linguistics; Language, General

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