Phonological contrast and neutralization by children with cochlear implants

Objective: To determine the degree to which pediatric users of cochlear implants (CIs) implement neutralization of the /t/ vs. /d/ contrast under different pragmatic conditions. Study design: Children who used cochlear implants and both children and adults with normal hearing produced minimal pairs contrasting lexical /t/ and /d/ in three conditions that gradually increased the need to differentiate members of the pairs, ranging from neutralization through implicit contrast to explicit contrast. Duration of the preceding vowel, the stop occlusion, and voice onset time following release were measured. Results: Adults exhibited small differences between /t/ and /d/ in the neutralization condition; differences increased through the remaining conditions. For the children, differences between /t/ and /d/ in the neutralization condition were relatively large, and differences between /t/ and /d/ did not increase monotonically through the conditions. Conclusion: Adults with normal hearing implement contrast and neutralization depending on pragmatic context. Children with either normal bearing or cochlear implants exhibit less differentiation, tending to maintain contrastiveness regardless of pragmatic condition. (c) 2004 Elsevier B.V. All rights reserved.