Consonant perception by adults with bimodal fitting

Many adults who receive a cochlear implant in one ear have usable residual hearing in the opposite ear. The simultaneous use of a cochlear implant (CI) and a hearing aid (HA) in the contralateral ear, or bimodal fitting, provides the recipient with potentially complementary information to the auditory system for speech perception, localization, and functional benefits in everyday life via two different modes of stimulation (acoustic and electric). This study investigated consonant perception in listeners who use bimodal fitting with the aim to identify the acoustic cues responsible for speech understanding when an HA is used together with a CI in comparison with the use of a CI alone. The results showed that on average, there was significant improvement in consonant recognition in quiet and in noise when adults wore CIs with HAs compared with CIs alone. Feature analysis of consonants was performed to directly examine what additional cues were provided by the HA to enhance consonant perception. This analysis showed that on average, there was a significant increase in reception of information about voicing in quiet conditions and about voicing and manner of articulation in noise. There was no difference in the transmission of information about place of articulation. The implications of these findings on rehabilitation of adults with unilateral CI are discussed.