Acoustic analysis of some speech discrimination abilities of normal and language impaired children

Abstract

The ability of 35 language impaired (LI) and 38 normally developing children between the ages of 5 and 9 years to discriminate between speech stimuli using an operantly conditioned, nonverbal motor response was investigated. Six syllable contrasts (/ba/ vs /da/, /da/ vs /ta/, /ε/ vs /ae/, /dab/ vs /daeb/, /sa/ vs /sta/ and /sa/ vs /∫s/) were selected to investigate discrimination of various temporal and spectral cues. Results demonstrated that the pattern of difficulty in discriminating the six stimulus pairs was different for the LI and normal children. The LI group made most errors on 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 normals in discriminating all syllables that incorporated brief temporal cues followed rapidly in succession by other acoustic cues. They also were impaired in discriminating /sa/ vs /∫a/. Constraints demonstrated by LI children may be attributed to abnormalities in mechanisms involved in auditory masking.