Dichotic speech recognition using CVC word and nonsense CVC syllable stimuli.

BACKGROUND The effects of stimulus material, lexical content, and response condition on dichotic speech recognition performance characteristics were examined for normal-hearing young adult listeners. No previous investigation has systematically examined the effects of stimulus material with constant phonetic content but varied lexical content across three response conditions typically used to evaluate binaural auditory processing abilities. PURPOSE To examine how dichotic speech recognition performance varies for stimulus materials with constant phonetic content but varied lexical content across the free recall, directed recall right, and directed recall left response conditions. RESEARCH DESIGN Dichotic speech recognition was evaluated using consonant-vowel-consonant (CVC) word and nonsense CVC syllable stimuli administered in the free recall, directed right, and directed left response conditions, a repeated measures experimental design. STUDY SAMPLE Thirty normal-hearing young adults (15 male, 15 female) served as participants. Participants ranged in age from 18 to 31 yr and were all right-handed. DATA COLLECTION AND ANALYSIS Participants engaged in monaural speech recognition and dichotic speech recognition tasks. Percent correct recognition per ear, as well as ear advantage for dichotic speech recognition, were calculated and evaluated using a repeated measures analysis of variance (ANOVA) statistical procedure. RESULTS Dichotic speech recognition performance for nonsense CVC syllables was significantly poorer than performance for CVC words, suggesting that lexical content impacts performance on dichotic speech recognition tasks. Performance also varied across response condition, which is consistent with previous studies of dichotic speech recognition. CONCLUSIONS Lexical content of stimulus materials impacts performance characteristics for dichotic speech recognition tasks in the normal-hearing young adult population. The use of nonsense CVC syllable material may provide a way to assess dichotic speech recognition performance while potentially lessening the effects of lexical content on performance.