Changes in speech production in post-linguistically deafened adults after cochlear implantation

Abstract

Introduction. This study investigated the effect of cochlear implantation on speech production of 20 post-linguistically deafened adults. Material and methods. Speech recordings were made before implantation and 3 and 12 months after implantation with the implant switched on and off. The material consisted of a reading-text, lists of h-vowel-t syllables and a sample of conversational speech. For the reading-text the mean fundamental frequency (f0) and the range over which f0 varied (the f0-sway) were calculated. The first and second formant frequencies and the intelligibility of vowels were determined for the h-vowel-t syllables. The conversational speech was judged by students of speech and language pathology. Results. Twelve months after implantation, with the implant switched on, mean f0 values were lower than before implantation. In addition, we found a decrease in the f0-sway. Both the formant measurements and the vowel-identification experiments showed improvement of vowel production. The subjective ratings showed improvements in supra-segmental aspects of speech production and vowel production. Conclusion. Post-linguistically deafened adults use the auditory information from the implant to improve their speech production.