Change of Phonation Control After Cochlear Implantation

Abstract

To assess the influence of acquired auditory control on some voice parameters in deaf children and adults after cochlear implantation. Prospective clinical study. Tertiary referral center. Twenty-nine prelingually deafened children and 11 postlingually deafened adults. The samples of a vowel /a/ were analyzed with an Multi-Dimensional Voice Program (Kay Elemetrics Corporation, Lincoln Park, NJ) before and 6 to 12 months after the cochlear implantation. The average fundamental frequency (F0), the short-term variation of F0 (JIT) and the amplitude (SH), the very long-term variation of F0 (vF0) and the amplitude (vAm), and the noise-to-harmonic ratio (NHR) were determined and compared for both age groups. The results of the acoustic analysis performed before the implantation were compared with the results after the implantation for children and adults. Significantly greater JIT, SH, vF0, and vAm were detected in the children than in the adults before and after the implantation. The prelingually deafened children significantly improved the control of their phonation after 6 to 12 months' use of the cochlear implant (JIT: p=0.014, SH: p=0.011, vF0: p=0.014, vAm: p=0.031). In the postlingually deafened adults, no significant improvement was found in any of the studied voice parameters after the implantation. F0 showed little or no change after the implantation in children and adults. As expected, the voice quality of the prelingually deafened children was significantly worse than that of the postlingually deafened adults. After cochlear implantation, the children significantly improved their short-term and long-term F0 and amplitude variability. In adults, no significant improvement was detected. We suppose that the improvement is a consequence not only of the acquired hearing control but also of the adaptation ability of neuromuscular phonation control and the maturing of these control mechanisms in children. In adults, better phonation quality in general and lesser improvement after the implantation can be the results of well-developed and stable phonation patterns.