Coarticulation Patterns and Speech Intelligibility in Cochlear Implant Users

This study investigates lingual articulatory configurations and coarticulatory patterns in the speech of young adult cochlear implant users, with a focus on their relation to speech intelligibility and clinical history. Previous research has shown that prelingually deaf cochlear implant users often differ from typically hearing speakers not only in speech sound articulation but also in coarticulatory behavior. However, the link between coarticulatory kinematics and intelligibility remains insufficiently understood, particularly in less studied languages such as Croatian. Seven participants with prelingual hearing loss and diverse clinical profiles were included in the study. They differed in age at implantation (2 to 10 years of age), onset of rehabilitation (0.9–6.2 years), and speech audiogram results. Speech material was elicited in a communicative setting approximating spontaneous speech. Ultrasound tongue imaging was used to analyze midsagittal tongue contours of the fricatives /s/ and /ʃ/ in symmetrical vowel contexts. Articulatory separation between the two fricatives was quantified using root mean square (RMS) distance scores, while coarticulatory variability was measured as differences in tongue contours across vowel contexts. Speech intelligibility was assessed by 32 trained listeners on a 7-point Likert scale. The results indicate that higher intelligibility scores were associated with greater coarticulatory variability, even when articulatory separation between /s/ and /ʃ/ was minimal. However, the results vary across speakers, suggesting a complex relation between articulatory separation, coarticulatory variability, and speech intelligibility in cochlear implant users. These findings highlight the importance of speech kinematics for understanding speech production in cochlear implant users and suggest potential clinical implications.