Infants' discrimination of intensity variation in multisyllabic stimuli.

Two groups of 5- to 11-month-old infants were tested for their ability to discriminate within-utterance intensity variations similar to those associated with linguistic stress. A visually reinforced discrimination procedure was used to determine sensitivity to increments in peak intensity for a final position, synthetic CVC syllable within either a bisyllabic (CVCVC) or a trisyllablic (CVCVCVC) context. Discrimination performance was above chance for a 2-dB increment, and improved for 4- and 6-dB increments. In addition, infants were more sensitive to intensity increments in the bisyllablic as compared to the trisyllabic context. Infant sensitivity for within-utterance intensity variations is sufficient for the detection of some linguistic stress contrasts.