Vibrotactile enhancement of Mandarin speech perception for cochlear implant users

Cochlear implants (CIs) have significantly restored speech perception for individuals with severe-to-profound hearing loss. However, CI users often struggle with pitch perception, recognition of lexical tone, and consonant identification, largely due to limited access to low-frequency components and coarse spectral resolution of the current CI devices. This is particularly challenging for tonal languages such as Mandarin, where accurate perception of tones and segmental contrasts is essential for speech intelligibility. This study investigates the potential of linguistically coded tactile stimulation to enhance CI speech perception. We recruited eight Mandarin-speaking CI listeners in Taiwan, all with congenital hearing loss and at least 3 years of CI usage. Vibrotactile signals were coded to deliver phonological features of Mandarin tones (high and low tonal registers) and consonant places of articulation (labial, alveolar and velar). Preliminary results show that phonologically encoded vibrotactile cues improved the perception of tone and place of articulation by 21% and 28%, respectively. The improvement in tone was expected, given the lack of representation of fundamental frequency in CIs, but the acoustic information for place of articulation occurs within typical CI bands. Therefore, the improvement in consonant identification holds promise for CI users in any language.