Speech acoustic-cue discrimination abilities of normally developing and language-impaired children

The ability of 35 language impaired (LI) and 38 normally developing children between the ages of 5 and 8 1/2 yr to discriminate between speech stimuli, using an operantly conditioned, nonverbal motor response, was investigated. Six syllable contrasts ([ba] versus [da], [da] versus [ta], [epsilon] versus [ae], [dab] versus [daeb], [sa] versus [sta] and [sa] versus [integral a]) were selected to investigate discrimination of various temporal and spectral cues. Results demonstrated that the LI group made most errors discriminating syllables which were differentiated by consonants and fewest errors on those differentiated by vowels. The normal group made most errors discriminating between syllables including fricatives and brief vowels and fewest errors on stimuli differentiated by stop consonants or vowels in context. The LI group was significantly poorer than the normal in discriminating all syllables that incorporated brief temporal cues followed rapidly in succession by other acoustic cues. They also were impaired in discriminating [sa] versus [integral a]. They were unimpaired discriminating stimuli differentiated by vowels. It is suggested that the particular constraints demonstrated by LI children in their nonverbal and speech processing abilities may be attributed to abnormalities in mechanisms involved in auditory masking.