Comparison the Voice Onset Time (VOT) of Postlingual Cochlear Implant Users and Normal Peers in the CAPE_V Sentences as Continues Speech Task.

BACKGROUND: Auditory perception plays a crucial role in speech and language development, emphasizing concerns about hearing loss. While cochlear implantation (CI) nearly tackles challenges associated with postlingual hearing loss in adults, the importance of "auditory feedback" and acoustic assessment becomes crucial for evaluating speech disorders and devising effective treatments. This study aims to address the gap in assessing Voice Onset Time (VOT) as an indicator of nuanced variations in the speech of CI users during a continuous speech task.

METHOD: Recordings of Persian CAPE-V sentences were obtained from 25 CI users and 25 healthy speakers, with a mean age of 33.2years (SD=11.5, range=18-55years). Ten words, incorporating both voiced and voiceless consonants, were selected from the CAPE-V sentences. VOT measurements for the specified stop consonants at the initial syllables of these chosen words were computed using PRAAT. A comparative analysis between the two age- and gender-matched groups was conducted using an independent sample t test. Subsequently, ANCOVA was employed to examine the influence of demographic factors on VOT values among CI participants.

RESULTS: Unvoiced consonant /p/ in /po/, /pɑ/, /pe/, and /pa/ syllables had higher VOT values in the healthy group, while the voiced consonant /d/ in /da/ and /di/ syllables demonstrated higher VOT values in the CI group (P < 0.05). Apart from /po/ and /di/ syllables, no significant impacts of demographic factors on VOT values were observed (P ≥ 0.8).

CONCLUSION: Despite the improvement in speech quality after CI, subtle differences persist. The motor theory, which underscores the impact of auditory inputs on temporal coordination, highlights the role of VOT in speech discrimination. Various linguistic factors affect VOT, including articulation position, vowel context, and raised vowels. While CI enhances syllable distinction, challenges in articulation for adults suggest a need for targeted training in rehabilitation programs, ultimately enhancing the quality of life for CI users.