Pupillometry as a Measure of Listening Effort in Patients with Bone-Anchored Hearing Systems

The goal of this study is to assess speech comprehension and listening effort by means of pupillometry, in patients with bone-anchored hearing system (BAHS). The study was performed prospectively in a group of 21 hearing-impaired adults, unilaterally implanted with BAHS Ponto. Listening effort was compared in patients wearing two sound processors (Oticon Medical AB, Askim, Sweden): Ponto 3 SuperPower (P3SP) and Ponto Pro (PP). Every patient was invited to two visits, separated by a 3-month break. The first session was to establish the noise level needed to obtain 95% correct sentence recall in the hearing in noise test (HINT), when speech is presented at 70 dB SPL. During the second session, pupillometry, with the use of the above-mentioned conditions, was performed. The mean HINT scores obtained during the second visit were 96.3% for PP and 97.7% for P3SP (p = 0.9863). In pupillometry, no significant differences were found for average PPD (peak pupil dilation; p = 0.3247), average peak pupil dilation timing (p = 0.527) and for pupil dilation growth curves with both processors. The findings of this study suggest that BAHS users allocate similar listening effort with PP and P3SP when processing speech-in-noise at a sound pressure level not saturating Ponto Pro and at a fixed performance level of 95%. This finding applies to the patients who meet the qualification criteria for bone conduction devices and have BC in situ threshold average below 45 dB HL.