Koklear İmplant Kullanıcılarında Bimodal Stimülasyon ile sağlanan Binaural İşitmenin Avantajları

Abstract

Demiröz B. G., The Benefits of Binaural Hearing Provided by Bimodal Stimulation in Cochlear Implant Users, Hacettepe University Graduate School of Health Sciences PhD Thesis in Audiology Program, Ankara, 2024. This study aimed to investigate fundamental frequency (F0) and vocal-tract length (VTL) voice cue discrimination thresholds and performance scores of speech perception in single talker background noise among cochlear implanted (CI, N=23), Bimodal (N=18), and normal hearing (NH, N=29) participants aged 10-30 years. Additionally, a subgroup of bimodal participants (N=11) was retested without hearing aids to further investigate acoustic input benefits. Participants were tested with two specifically developed experiments for voice cue discrimination and speech perception, focusing specifically on F0 and VTL cues. Results revealed that, CI and bimodal children had lower sensitivity F0 and VTL discrimination thresholds compared to their normal hearing peers, but children performed better than postlingual CI adults. CI and Bimodal children performed better in speech perception tests, primarily benefiting from increasing TMR and voice cue differences. The CI and Bimodal children whose F0 thresholds overlapped with NH children were observed to have been implanted early. Test-retest analysis in Bimodal participants showed no significant effect of hearing condition on F0 and VTL sensitivity, hovewer, increasing TMR and using hearing aids (HAs) in the contralateral ear improved accuracy scores in some participants. In conclusion, although CI and Bimodal participants had lower voice cue discrimination thresholds compared to NH peers, they utilized degraded F0 cues to some extent for perception despite spectrotemporal challenges, while VTL cues were more challenging. Moreover, acoustic input via HAs had a benefit on speech perception in some participants. Further exploration of individual visual inspection and demographic details may offer deeper insights into influencing factors on individual variations and performance.