Auditory Lexical Decision and Repetition in Children: Effects of Acoustic and Lexical Constraints

Objectives: The objective of this study was to identify factors that may detract from children’s ability to identify words they do and do not know. Factors investigated were acoustic constraints stemming from the presence of hearing loss (HL) or an acoustic competitor, and lexical constraints due to an impoverished or cluttered vocabulary. Design: Eleven children with normal hearing (NH) and 11 children with bilateral, mild to moderately severe sensorineural HL were asked to categorize and repeat two-syllable real and nonsense words. Stimuli were amplified and frequency shaped for each child with HL and presented randomly at a level consistent with average conversational speech (65 dB SPL). About half of the children in each group listened in quiet while the other half listened in multitalker babble. In addition to overall performance, responses were judged based on the word category chosen by the child (real or nonsense), the category of the word produced by the child as judged by an examiner (real or nonsense), and the accuracy of the verbal response compared with the stimulus. From these judgments, 10 discrete types of errors were identified. Analyses were conducted for three different combinations of the 10 error categories to best characterize the effects of acoustic and lexical constraints. Results: Performance was highest for real words presented in quiet and poorest for nonsense words presented in multitalker babble. Also, the performance of the children with HL was poorer than that of the children with NH. Error analyses revealed strong effects of acoustic constraints on performance but few effects of lexical constraints. The two most frequently occurring errors were the same for both children with NH and the children with HL and entailed the misperception of nonsense words and the mistaking of nonsense words for real words. However, while both groups of children exhibited these errors in multitalker babble, the children with HL demonstrated these errors in quiet as well. Conclusions: These results suggest that children’s interactions with real and nonsense words are significantly constrained when the acoustic signal is degraded by HL and/or an acoustic competitor. The children’s tendency to repair unknown words into real words in the presence of acoustic interference may be beneficial when perceiving familiar speech, but could also be detrimental if that tendency causes them to miss opportunities to learn new words.

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