Effects of Complementary Auditory Feedback in Robot-Assisted Lower Extremity Motor Adaptation

This study investigates how complementary auditory feedback may affect short-term gait modifications induced by four training sessions with a robotic exoskeleton. Healthy subjects walked on a treadmill and were instructed to match a modified gait pattern derived from their natural one, while receiving assistance by the robot (kinetic guidance). The main question we wanted to answer is whether the most commonly used combination of feedback (i.e., haptic and visual) could be either enhanced by adding auditory feedback or successfully substituted with a combination of kinetic guidance and auditory feedback. Participants were randomly assigned to one of four groups, all of which received kinetic guidance. The control group received additional visual feedback, while the three experimental groups were each provided with a different modality of auditory feedback. The third experimental group also received the same visual feedback as the control group. Differences among the training modalities in gait kinematics, timing and symmetry were assessed in three post-training sessions. Results of this study indicate that the combination of kinetic and visual guidance may be as effective as the combination of kinetic guidance and external rhythmic cues whose frequency corresponds to the cadence of the altered footpath. Conversely, adding a subject-triggered rhythm to kinetic and visual guidance did not lead to significant improvements compared to the control group.