Speech Recognition and Cognitive Skills in Bimodal Cochlear Implant Users

To examine the relation between speech recognition and cognitive skills in bimodal cochlear implant (CI) and hearing aid users.

Seventeen bimodal CI users (28-74 years) were recruited to the study. Speech recognition tests were carried out in quiet and in noise. The cognitive tests employed included the Reading Span Test and the Trail Making Test (Daneman & Carpenter, 1980; Reitan, 1958, 1992), measuring working memory capacity and processing speed and executive functioning, respectively. Data were analyzed using paired-sample t tests, Pearson correlations, and partial correlations controlling for age.

The results indicate that performance on some cognitive tests predicts speech recognition and that bimodal listening generates a significant improvement in speech in quiet compared to unilateral CI listening. However, the current results also suggest that bimodal listening requires different cognitive skills than does unimodal CI listening. This is likely to relate to the relative difficulty of having to integrate 2 different signals and then map the integrated signal to representations stored in the long-term memory.

Even though participants obtained speech recognition benefit from bimodal listening, the results suggest that processing bimodal stimuli involves different cognitive skills than does unimodal conditions in quiet. Thus, clinically, it is important to consider this when assessing treatment outcomes.