Evaluation of Consonant Error Patterns in Speech Perception and Production of Pediatric Cochlear Implant Users

This dissertation uses the framework of the speech chain to examine the associations between perception/production and associated error patterns in children using cochlear implants (CIs), children with normal hearing (NH), and children with NH listening to vocoder simulations (NHV). Chapter 1 introduces background information on the populations represented by the three groups. This chapter focuses on typical perception and production development and introduces the challenges in evaluating perception and production patterns in children with hearing loss (HL). Chapter 2 examines the association between consonant perception, production error patterns and speech ineligibility in two groups of children using CIs: one group implanted at early ages using newer CI technologies, and the other group implanted at later ages using older CI technologies. Data from the Chapter 2 helps to establish the methodological basis for constructing a new database described in the Chapter 3. Chapter 3 examines perception and production error patterns in children using CIs who were implanted after 2010 using newer CI technologies in comparison to NH and NHV control groups. Chapter 4 provides a general discussion that relates the findings of these three studies. Results from Chapter 2 indicate lower speech perception scores with a higher number and greater variability of errors in the CI group implanted with older technologies compared to the CI group implanted with newer technologies. Methodological limitations in the data presented in Chapter 2 did not permit a direct comparison of errors in consonant production and perception. The testing procedures developed in Chapter 3, which allowed for such comparisons, showed that production and perception error patterns generally did not mirror one another. Although no overall differences in mean error rate were observed between CI and NH groups, the error patterns for individual consonants in these groups were different. Perception performance of children in the NHV group was worse than in CI group suggesting caution is needed when interpreting CI vocoder simulation studies in children. The results provide important clinical information suggesting that intervention for children using CIs needs to consider how speech perception confusions interact with the production errors in order to develop more effective techniques for including them in clinical protocols.