An investigation of speech production and intelligibility of a post‐lingually deaf sequential bilingual adult cochlear implant user, pre‐ and post‐implantation for English and Twi.

Abstract

This study investigates changes in speech production for a sequential bilingual adult male who is postlingually deaf (9 years of hearing) following cochlear implantation (CI). Recordings of words in carrier phrases took place at pre‐implantation in English (L2) and at the 6‐month, 1‐year, 1‐year‐6‐month, and 2‐year post‐implantation marks in L2 and Twi (L1). Normative data were recorded from a typically hearing adult male with a similar linguistic history. Acoustic measurements for L2 include f0, F1, and F2 of vowels, VOT, and spectral measures of s‐S. Voice quality measurements for sustained /a/ were also obtained. Acoustic measurements for L1 include F1 of vowels that undergo vowel harmony and f0 of tonal contrasts. Questionnaires about CI usage and self‐reported changes in production/perception supplement the acoustic data. Lastly, forced‐choice speech intelligibility ratings in L1 and L2 were obtained utilizing inexperienced monolingual listeners of each language separately. Current results suggest preservation of L1 following 16 years of auditory deprivation, phonetic influence of L1 on L2, and fluctuating suprasegmental parameters. These acoustic data will be compared to intelligibility ratings and information from the self‐report questionnaires.