Perceptual organization of Mandarin consonants in cochlear implant users

This study provides a systematic characterization of Mandarin consonant perception in adult cochlear implant (CI) users and benchmarks the resulting perceptual organization against a condition-matched hearing-aid (HA) dataset and a previously reported normal-hearing (NH) reference. Thirty-five Mandarin-speaking CI listeners completed a 21-alternative closed-set identification task using 21 /C(i)ā/ syllables presented in quiet. Data were analyzed using accuracy, hierarchical clustering, multidimensional scaling, and feature-based information transmission. CI listeners achieved moderate overall accuracy (68%), with the greatest difficulty for aspirated stops (notably p and t) and several high-frequency sibilants. Furthermore, confusion analyses revealed a structured but compressed perceptual organization under device-mediated hearing. Both CI and HA data were well described by a two-dimensional perceptual space (NH required at least three), anchored by robust contrasts of sonorancy and aspiration, with other distinctions (including place, manner, and sibilance) collapsed into a narrow band of partial separability. Within this shared compression, CI and HA diverged in the perceptual organization supported by residual cues: HA showed stronger sonorant and aspiration-aligned organization, whereas CI showed a relatively clearer broad obstruent-manner organization. Together, these findings provide new insight into how device-mediated hearing restructures the perceptual organization of Mandarin consonants beyond overall accuracy.