Processing of linguistic and indexical information in adult cochlear implant users

Abstract

Normal-hearing (NH) listeners simultaneously make use of both linguistic (speech content) and indexical (talker-specific) information in speech perception. For adult cochlear implant (CI) users, limitations in the talker-specific details conveyed by their devices may impact processing dependences between linguistic and indexical information. The current study examined the extent to which linguistic and indexical information are processed interdependently in adult CI users, using speeded phoneme and talker gender classification tasks. Higher-performing adult CI users (open-set word recognition >65% correct) reported the target vowel (phoneme classification) or target talker gender (gender classification). The non-target dimension varied by the number of talkers (phoneme classification) and the number of words (gender classification). Largely consistent with NH findings, adult CI users displayed asymmetric interference between linguistic and indexical dimensions. Phoneme classification was less accurate and slower with high talker variability. In contrast, gender classification was not affected by word variability. Processing dependencies also varied across individual CI users and related to auditory and cognitive-linguistic abilities. These preliminary findings suggest that adult CI users may make use of degraded linguistic and indexical information during speech processing. However, the extent to which they do so may depend on individual auditory and cognitive-linguistic factors.