Meta-analysis on lexical tone recognition in cochlear implant users

Lexical tone plays a vital role in speech communication in tonal languages. This study investigated lexical tone recognition in cochlear implant (CI) users, and identified potential factors that influence lexical tone recognition in the CI population. We conducted a systematic search across eleven major databases, evaluated the risk of bias in the included studies, and conducted five meta-analyses. Forty studies that utilised a multi-item alternative forced-choice paradigm were included to evaluate the performance of lexical tone recognition in CI users. CI users performed worse at recognising lexical tones than normal hearing (NH) controls. Furthermore, bimodal stimulation could benefit lexical tone recognition for CI users in both quiet and noisy conditions. Besides, the pooled results showed a negative correlation between tone recognition accuracy and age at implantation, as well as a positive correlation between tone recognition performance and the duration of CI experience. This study indicates that CI users could not recognise lexical tones at the same level as the NH population. The bimodal intervention does have a more positive effect than unimodal implantation regardless of the listening environment. Moreover, earlier implantation and longer experience with the CI could facilitate lexical tone recognition.