Combined Electric and Contralateral Acoustic Hearing for Speech Perception and Immediate Phonological Memory

Purpose: This study examined the benefit of bimodal hearing (i.e., one cochlear implant and a contralateral hearing aid) for listening to words and sentences in quiet and in noise, the identification of vowels and immediate phonological memory. Method: Two groups of twenty adult cochlear implant recipients, those who used bimodal hearing on a regular basis, and those who used one cochlear implant, were recruited for this study. They were asked to complete two speech perception tests, the Consonant Nucleus Consonant (CNC) test, and sentences in quiet and in noise from the Hearing In Noise Test. In addition, participants were asked to identify groups of vowels that were either acoustically similar or acoustically distinct. Immediate phonological memory skills were assessed by asking the participants to recall sequences of vowels. Results: The outcomes suggested that the use of bimodal hearing did not provide sufficient acoustic cues to aid with the identification of words, sentences in quiet and in noise, isolated vowels, and immediate memory for sequences of vowels compared to the use of one cochlear implant. A larger degree of residual hearing prior to implantation was, however, associated with improved performance when identifying isolated words and listening to sentences in noise. The ability to recognize isolated vowels and the short-term memory for sequences of vowels were both positively correlated with speech perception skills. Conclusions: The use of a contralateral hearing aid with a cochlear implant did not provide sufficiently greater benefit for identifying words, sentences in quiet and in noise, isolated vowels, and the immediate memory for those vowels, compared to the use of one cochlear implant alone. Vowel identification and immediate phonological memory, however, were moderately correlated.