Perception of vowels and consonants in cochlear implant users

Although cochlear implants (CI) improve speech intelligibility, they introduce distortions of the sensory input to the auditory system, and modify the transmission of acoustic cues. This study evaluated perception of consonants and vowels in experienced postlingual adult CI users. Twenty-five experienced CI users were tested with The Modified Rhyme Test (MRT) of consonant perception (word-initial and word-final) and a closed-set vowel test containing 12 vowels in the /hVd/ context. Overall consonant perception accuracy was 80%. No significant difference was observed in identification of word-initial or word-final consonants. There was significant variation in consonant accuracy in terms of place and manner, but not voicing. For place, alveolar consonants had the lowest accuracy. For manner, nasals were the least identifiable. Overall vowel identification accuracy was 76%. Accuracy was higher for front vowels than back vowels. The three most accurately identified vowels were (/i/), (/I/), and (/Ω/). The three least accurately identified vowels were (/a/), (/ɔ/), and (/u/). There was a considerable variation in consonant and vowel perception across CI users. The pattern or consonant and vowel confusions can inform CI programming and rehabilitation to improve speech perception.