Middle Ear Implant Usage Restores Subjective Listening Effort toward Normal in Complex Acoustic Scenes

Introduction: The amount of listening effort needed to understand speech in every-day life is an important outcome measure of the effectiveness of a hearing device. The main goal of this study was to assess subjective listening effort in patients implanted with an active middle ear implant Vibrant Soundbridge (VSB) with and without using their speech processor in complex acoustic scenarios. Methods: Ten VSB users were measured using the adaptive categorical listening effort scaling (ACALES) method in four different acoustic scenarios, realized using a multichannel loudspeaker array. The four acoustic scenarios included both spatially simple and complex speech and noise arrangements that realistically simulated challenging every-day listening situations. Signal-to-noise ratios (SNRs) were adaptively varied during the measurement. Twelve normal-hearing (NH) listeners performed the same experiment as a control group. Results: Listening effort was significantly reduced in all tested acoustic scenarios when participants used their VSB. When using the VSB, SNRs corresponding to mild-to-moderate listening effort were found not to be statistically different from SNRs found in the NH control group. SNRs corresponding to extreme listening effort of VSB users approached NH values, indicating partial restoration of listening effort. Discussion and Conclusions: Usage of the middle ear implant VSB was found to restore subjective listening effort to normal at high SNRs completely, and at lower SNRs partially. The remaining gap at low SNRs may be due to lower effectiveness of signal processing at high noise levels or due to the microphone location effect.