Effect of acoustic‐cue redundancy of perception of stop‐vowel syllables by language‐delayed children

Abstract

Previous studies demonstrated that language‐delayed children have difficulty processing speech signals (such as stop‐vowel syllables) which incorporate brief‐duration acoustic cues [P. Tallal and M. Piercy, Neuropsychol. 12, 83–93 (1974)]. The present study was designed to determine whether the presence of multiple cues to the place feature in stop‐vowel syllables would make a speech processing task more or less difficult for language‐delayed children. Five‐ through eight‐year‐old language‐delayed and normal children were trained to respond nonverbally to three pairs of syllables. The three pairs were phonologically the same /ba/ and /da/), but the pairs differed in the number of acoustic cues present. Pairs 1 and 2 were synthesized with two and three formants, respectively. Pair 3 was produced naturally (with multiple cues). The normal children's performance did not change significantly from one pair to another. All syllables were 250 ms in duration with 40‐ms formant transitions. However, the language‐delayed children's performance was significantly below normal for the two‐formant ba/da pair (p < 0.001), for the three‐formant ba/da pair score differences were less highly significant (p < 0.01), and for the real‐speech pair there was no significant difference between groups. These results suggest that acoustic redundancy aids language‐delayed children in responding to rapidly changing portions of the speech signal. [Work supported by NINCDS.]