Objective and subjective evaluation of listening effort in unilateral cochlear implant user individuals

The listening effort is defined as using cognitive resources to overcome challenges that depend on the person and/or the feature of auditory stimulus during a specific listening task. In this study, the benefits and limitations of the pupillometry method, which is very important for the objective measurement of listening effort in clinical practice, and accordingly its applicability in the evaluation of individuals with hearing loss are explained. The aim of this study is to objectively and subjectively evaluate the listening effort of unilateral cochlear implant(CI) users and compare with normal hearing individuals. Using Turkish Matrix test sentences in a total of 28 individuals with 14 unilateral CI user and 14 normal hearing who are native Turkish in this study, the Matrix was arranged to test each group monaural in 2 different cases based on the differentiation thresholds of 50% and 70% in the noise within the test. The listening effort was evaluated by recording pupil size and response time through the dual task paradigm. The primary task of the study was to repeat the auditory stimuli, and the secondary task was to find rhymes between phonetically balanced monosyllabic words presented visually. The study resulted in significant correlation between measurements of answer time and pupil size (r =, 177, p < .001). In pupil size measurements, when the speech intelligibility threshold was increased from 50% to 70% in the Turkish Matrix test, although the intelligibility rates increased especially in the CI group, no significant change was observed in pupil size. The variation of 50% and 70% intelligibility levels made a significant difference in the normal hearing group. For response time measurements, there was a significant difference between the study and the control group at the SDT level of 70%. As a result, when the level of intelligibility increased, the response time was found to be longer in the cochlear implant group compared to the normal hearing group.