Objective: We sought to validate our proposed tool for estimating channel discrimination of cochlear implant (CI) users along the full electrode array and to assess associations between place-pitch... Show moreObjective: We sought to validate our proposed tool for estimating channel discrimination of cochlear implant (CI) users along the full electrode array and to assess associations between place-pitch discrimination and speech perception. Design: In two tests, participants identified one stimulus (probe) as the odd-one-out compared with two reference stimuli. Probe stimuli were evoked using dual electrode stimulation characterised by the current steering coefficient alpha. The first test measured psychometric functions (PFs) on pre-defined contacts, with just a noticeable difference (JND alpha) as the outcome variable. The second test estimated channel discrimination on the full electrode array, yielding a discrimination score of D alpha. We measured speech perception as free-field consonant-vowel-consonant phoneme recognition scores. Study sample: We included 25 adults with at least 6 months of CI experience. Results: JND alpha and D alpha scores measured on the same contact correlated significantly (r(s) = 0.64, p < 0.001). Mean JND alpha and speech perception scores showed significant relationships in quiet and in noise. Conclusions: D alpha correlated strongly with JND alpha scores obtained with the PFs. For poor performers, the full-array test may underestimate JND alpha. The full-array pitch discrimination test could be a helpful clinical tool, such as for fitting regions of lesser pitch discrimination ability. Show less
ObjectiveWe sought to validate our proposed tool for estimating channel discrimination of cochlear implant (CI) users along the full electrode array and to assess associations between place-pitch... Show moreObjectiveWe sought to validate our proposed tool for estimating channel discrimination of cochlear implant (CI) users along the full electrode array and to assess associations between place-pitch discrimination and speech perception.DesignIn two tests, participants identified one stimulus (probe) as the odd-one-out compared with two reference stimuli. Probe stimuli were evoked using dual electrode stimulation characterised by the current steering coefficient α. The first test measured psychometric functions (PFs) on pre-defined contacts, with just a noticeable difference (JNDα) as the outcome variable. The second test estimated channel discrimination on the full electrode array, yielding a discrimination score of Dα. We measured speech perception as free-field consonant-vowel-consonant phoneme recognition scores.Study sampleWe included 25 adults with at least 6 months of CI experience.ResultsJNDα and Dα scores measured on the same contact correlated significantly (rs = 0.64, p < 0.001). Mean JNDα and speech perception scores showed significant relationships in quiet and in noise.ConclusionsDα correlated strongly with JNDα scores obtained with the PFs. For poor performers, the full-array test may underestimate JNDα. The full-array pitch discrimination test could be a helpful clinical tool, such as for fitting regions of lesser pitch discrimination ability. Show less
Objective: To test the channel discrimination of cochlear implant (CI) users along all contacts of the electrode array and assess whether this is related to speech perception.Design: CI recipients... Show moreObjective: To test the channel discrimination of cochlear implant (CI) users along all contacts of the electrode array and assess whether this is related to speech perception.Design: CI recipients were tested with a custom-made channel discrimination test. They were asked to distinguish a target stimulus from two reference stimuli in a three-alternative forced choice (3AFC) task. The target stimulus was evoked using current steering, with current steering coefficients () of 1, 0.5 and 0.25. The test provided a discrimination score (D) for each electrode contact along the array.Study sample: Thirty adults implanted with a CI from Advanced Bionics.Results: Large variations in D scores were observed, both across the electrode array and between subjects. Statistical analysis revealed a significant channel-to-channel variability in D score (p<0.01). Further, there was a significant relationship between subjects' D scores and their speech perception in quiet (p<0.001).Conclusions: The large variations in D score emphasise the importance of testing pitch discrimination across the complete electrode array. The relationship between D score and speech perception indicates that pitch discrimination might be a contributing factor to the performance of individual implant users. Show less
