Speech characteristics in early implanted children compared to hearing aid users

Goal: The speech of deaf children is often characterized by difficulties in articulation, phonation, and resonance which can adversely affect the overall intelligibility. This study investigate the above mentioned aspects of speech production of 40 Flemish CI children and compare these aspects with those of 34 children using hearing aids (HA) and 42 normal hearing (NH) children. Methods: Speech samples were video-recorded for further phonetic and phonological analysis. The F1 and F2 of the vowels [a], [i] and [u] were measured using the PRAAT software. The objective vocal quality was perceptual evaluated and measured by means of the Dysphonia Severity Index (DSI). Nasal resonance was investigated using the Nasometer and perceptual evaluations. Finally, intelligibility was perceptually judged using a five-point hierarchical scale and a U+201Cpercentage of words correctly understoodU+201D was calculated. Results: The consonant production of CI children is more adequate than the production of HA children with a hearing loss of 70dB or more. The vowel production in CI children and HA children is characterised by several subtle but significant deviations compared to NH children. The mean DSI value of the CI children was not significantly different from those of the NH children and HA children. But the voice of CI and HA children was characterized by a slight grade of hoarseness, roughness and strained phonation. In the HA children also higher pitch and intensity levels ware observed. CI children as well as HA children showed lower nasalance values for nasal stimuli compared to NH children but higher nasal values for the oral stimuli. In both, cul-de-sac-resonance was observed on a significantly larger scale than in the NH group, and the HA children were judged to be significantly more hypernasal compared to NH children. The intelligibility of the CI children appears to be very close to the intelligibility of NH children. The HA children on the other hand, showed inferior intelligibility scores. Conclusion: CIU+2019s are shown to have a beneficial effect on the speech production and intelligibility, of deaf children. This results in speech production outcomes higher than in moderate-to-severely hearing impaired HA children and even comparable to NH children in some cases. On the other hand, this study also describes possible speech production errors which can persist after implantation.