Both perceptual and acoustic studies of children’s speech independently suggest that phonological contrasts are continuously refined during acquisition. This paper considers two traditional acoustic features for the ‘s’-vs.-‘sh’ contrast (centroid and peak frequencies) and a novel feature learned from data, evaluating these features relative to perceptual ratings of children’s productions.

Productions of sibilant fricatives were elicited from 16 adults and 69 preschool children. A second group of adults rated the children’s productions on a visual analog scale (VAS). Each production was rated by multiple listeners; mean VAS score for each production was used as its perceptual goodness rating. For each production from the repetition task, a psychoacoustic spectrum was estimated by passing it through a filter bank that modeled the auditory periphery. From these spectra centroid and peak frequencies were computed, two traditional features for a sibilant fricative’s place of articulation. A novel acoustic measure was derived by inputting the spectra to a graph-based dimensionality-reduction algorithm.

Simple regression analyses indicated that a greater amount of variance in the VAS scores was explained by the novel feature (adjusted R² = 0.569) than by either centroid (adjusted R² = 0.468) or peak frequency (adjusted R² = 0.254).