A Comparative Study of Voice Characteristics in Children With Cochlear Implants and Typically Hearing Children: Insights From an Indian Context

Purpose The aim of the study was to evaluate speech outcomes in children with cochlear implants compared to normally hearing children in terms of fundamental frequency, shimmer, and jitter. The study also aims to assess the intelligibility of speech in children with cochlear implants using a speech intelligibility rating scale. Methods This was a hospital-based comparative study conducted at JIPMER, a major tertiary referral center. A total of 25 prelingually deaf children with profound deafness, who underwent cochlear implantation at the institute, were recruited from the outpatient department of the Department of Otorhinolaryngology. Twenty-five children under seven years of age who underwent cochlear implantation and received a minimum of 36 speech therapy sessions were included in the study. Subjects with incomplete electrode array insertion and any neurological maldevelopment were excluded. Age- and gender-matched controls comprising 25 individuals were selected from the Ophthalmology Outpatient Department at JIPMER. Study procedure The study commenced in January 2019. Test subjects were asked to visit the Audiology and Speech and Language Pathology Department at JIPMER. Voice recordings were conducted in a soundproof room using a microphone, with the mouthpiece held at a distance of 10-15 cm from the patient. The patient was instructed to say "a" three times. Their voice was recorded and analyzed using Praat software (Version 6.1.15, developed by Paul Boersma and David Weenink, Phonetic Sciences, University of Amsterdam). Data were analyzed using IBM SPSS Statistics for Windows, Version 19 (Released 2010; IBM Corp., Armonk, New York) (Department of Biostatistics, Vanderbilt University, Nashville, Tennessee, USA), and the results were derived. Results The mean fundamental frequency for Group 1 (CI) was 266.03 ± 57.46 Hz, compared to 312.97 ± 22.15 Hz for Group 2 (NH). There was a statistically significant difference between the values of both groups, indicating that cochlear implantation positively impacted the fundamental frequency of speech. The study revealed a significant change in the fundamental frequency when children were implanted at an early age and received effective speech therapy post-implantation. This change was assessed after one year post-implant. Perturbation measures such as shimmer and jitter were lower in the cochlear implant group but were not statistically significant. Conclusion Children with congenital bilateral severe to profound sensorineural hearing loss tend to have higher values of the fundamental frequency of speech. However, when implanted at an early age, they showed a significant difference in the fundamental frequency of speech (p < 0.001). Speech perturbation was lower in the post-cochlear implant group, with a statistically significant difference in the values of shimmer alone. The study concludes that children with cochlear implants can achieve normal voice parameters with early intervention and training. However, the variability range is much higher than in typically hearing individuals.