Digit span recall error analysis in pediatric cochlear implant users.

The errors made by 37 pediatric cochlear implant users and age-matched normal- hearing children during forward and backward digit span recall were analyzed. All children were between 8 and 10 years old. The children who used implants had at least 4.5 years of experience with their device. Error classification was made using four categories: item, order, omission, or combination errors. Recall of digits not presented on a given trial was classified as item errors. The recall of all correct digits in an incorrect order was considered to be an order error. Results from a univariate ANOVA revealed main effects for error type, recall condition, and hearing ability. In addition, the error type by recall condition interaction revealed that order errors increased more in backward digit span recall than any other type of error for both normal-hearing children and children with cochlear implants. The present results are consistent with previous studies, suggesting that the shorter digit spans of children using cochlear implants are not primarily related to perceptual difficulties but appear to reflect memory processing problems related to slower subvocal verbal rehearsal and serial scanning of items in short-term memory.

Perceptual learning and nonword repetition using a cochlear implant simulation.

This study examined the effects of perceptual learning on nonword repetition performance of normal-hearing listeners who were exposed to severely degraded auditory conditions that were designed to simulate the auditory input of a cochlear implant. Twenty normal-hearing adult listeners completed a nonword repetition task using an eight-band, frequency-shifted cochlear implant simulation strategy both before and after training on open- and closed-set word recognition tasks. Feedback was provided during training. The nonword responses obtained from each participant were digitally recorded and played back to normal-hearing listeners. These listeners rated the nonword repetition accuracy in comparison to the original unprocessed target stimuli using a seven-point scale. The mean nonword accuracy ratings were significantly higher for the non words repeated after training than for non words repeated prior to training. These results suggest that the word recognition training tasks encouraged auditory perceptual learning that generalized to novel, nonword auditory stimuli. The present findings also suggest that adaptation and learning from the degraded auditory stimuli produced by a cochlear implant simulation can be achieved even in a difficult perceptual-motor task such as nonword repetition which involves both speech perception and production of an auditory stimulus that lacks any lexical or semantic representation.