Analysis of different speech performance in patients with multi-channel cochlear implants

Totally 41 postlingually deafened adult patients who have received multi-channel cochlear implants at Stockholm Söder Hospital have participated in this study. All patients have followed the CI-programme at the clinic and have been tested 0, 6, 12, and 24 months postoperatively. The test-battery consisted of vowels (cVc) and consonants (vCv), Everyday Sentences(ES), and Connected Discourse Tracking (CDT) presented in two modalities: cochlear implant plus lip-reading and implant alone. Results for the 41 patients from the speech tests showed an improvement, on average, within the first 6 months of implant use. Some patients, however, get high scores from the beginning, while others gradually improved over a 2-year period. The patients have been divided into three groups POOR (11), AVERAGE (13) and GOOD (17) based on their performance auditory alone on Connected Discourse Tracking test. Group mean results on consonants, showed that for patients with AVERAGE and GOOD speech understanding, errors in recognition of voicing were rare but nasals were poorly perceived. For the POOR-group, envelope cues seem to dominate the consonant recognition. The fricative [ ] was well identified by all patients in the three groups. Results are discussed in relation to etiology of deafness, years of deafness and other factors.