Listening Effort in Cochlear Implant Users: Benefits of Bimodal Listening

Introduction: Listening effort (LE), the mental resources necessary to accomplish a listening task, often remains high in cochlear implant (CI) users. Bimodal listening – use of a CI combined with a contralateral hearing aid (HA) – may decrease LE, free up cognitive resources, and result in less fatigue compared with CI-listening alone. The objectives of this research were to establish a clinically useful test of LE and determine LE differences in bimodal, bilateral, and unilateral CI users. We predicted that bimodal listening would decrease LE, particularly under challenging listening conditions.

Methods: In this prospective cohort study, 10 bimodal, 10 bilateral, and 4 unilateral CI users were recruited from a tertiary adult Neurotology center. The Sentence Final Word Identification and Recall Task (SWIR), an established measure of LE, was modified to include challenging listening conditions (multi-talker babble, gender, and emotional variation; test), in addition to single-talker sentences (control). Participants listened to lists of sentences in each condition, and recalled the last word of each sentence. LE was quantified by percentage of words correctly recalled and was compared across conditions, across CI groups, and within subjects (best-aided vs. monaural conditions).

Results: LE was higher (i.e. lower recall) for all groups with gender and emotional variation compared to the control condition (p < 0.05). Preliminary analyses suggest a trend towards a bimodal benefit in LE in test vs. control conditions, for both the between subjects and within subjects comparisons. Bimodal participants had lower LE than CI-only groups and showed a relatively greater increase in LE in the monaural condition compared to CI-only groups.

Conclusions: Our findings suggest that the SWIR could be a useful clinical task for evaluation of LE in patients who might benefit from addition of a hearing aid after unilateral CI implantation. Preliminary results suggest that bimodal configuration might decrease LE in more challenging listening conditions, which will be explored further through future studies.