Development of a speaker discrimination test for cochlear implant users based on the Oldenburg Logatome corpus

The purpose of the study was to develop a speaker discrimination test for cochlear implant (CI) users. The speech material was drawn from the Oldenburg Logatome (OLLO) corpus, which contains 150 different logatomes read by 40 German and 10 French native speakers. The prototype test battery included 120 logatome pairs spoken by 5 male and 5 female speakers with balanced representations of the conditions 'same speaker' and 'different speaker'. Ten adult normal-hearing listeners and 12 adult postlingually deafened CI users were included in a study to evaluate the suitability of the test. The mean speaker discrimination score for the CI users was 67.3% correct and for the normal-hearing listeners 92.2% correct. A significant influence of voice gender and fundamental frequency difference on the speaker discrimination score was found in CI users as well as in normal-hearing listeners. Since the test results of the CI users were significantly above chance level and no ceiling effect was observed, we conclude that subsets of the OLLO corpus are very well suited to speaker discrimination experiments in CI users.