Developmental differences in identifying and discriminating CV syllables.

The purpose of this experiment was to determine whether age-related differences would be observed for identification and discrimination of synthesized, five-formant CV syllables among listeners who showed equal performance scores on a standard clinical test of speech understanding. A second question concerned the relations between performance on identification and discrimination tasks as a function of age. Two 13-item continua that varied in the place of articulation feature ([ba, da, ga]) were used; they differed primarily in the presence of absence of a 5-ms noise burst at the consonant onset. Digitized natural speech syllables were also employed in one experimental task. Strong age effects were obtained for the three tasks--identification of syllables, adaptive estimation of "ba, da-" and "da, ga-" boundaries, and discrimination. With the exception of one condition for six-year-olds, only adults showed significant differences between boundaries and just noticeable differences. Minimal differences were obtained in responses to stimuli with and without initial bursts. Across ages there were no significant differences in the subjects' ability to label the synthesized syllables as compared to the natural speech stimuli. Possible explanations for the observed developmental effects are discussed.