Infants' discrimination of final syllable fundamental frequency in multisyllabic stimuli

Two groups of nine, 5- to 11-month-old infants were tested for discrimination of a change in peak fundamental frequency (F0) within the final syllable of multisyllabic speechlike stimuli. A visually reinforced headturn discrimination procedure was used to determine sensitivity to increments in peak F0 in synthetic speech in both bisyllabic (CVCVC) and trisyllabic (CVCVCVC) contexts. Discrimination performance was above chance expectation for increments of 10, 20, and 30 Hz relative to a 150-Hz standard. There were no differences in performance attributable to syllable-number context. In a second experiment reassessing two-syllable stimuli, performance was above chance for increments of 5, 10, and 30 Hz relative to the same 150-Hz standard. Both experiments indicated a relatively flat function relating discrimination score and F0 increment. Overall, infant and adult absolute thresholds for a change in F0 appear similar. Effects of threshold, increment, and syllable number are contrasted with earlier results for infant discrimination of both peak-intensity changes and vowel duration increments in the same multisyllabic stimuli.