Hearing Amplification Improves Eye Movements: A Case Study
Background: Using two different approaches, we study the possible interaction between the sound and the preparation and execution of eye movements. The first approach deals with the sensory modalities of the target to which eye movements are made, the second with the hearing amplification of the subject. Material: Saccades and vergence were tested for a healthy 19-year-old student performing his internship in the lab. Tests with visual vs audiovisual targets were done. The normal hearing participant performed all tests with a hearing bilateral device that was adjusted in different conditions either at zero (no amplification), moderate amplification, or high amplification. Experimentations were made over a month, and the different tests were executed following a Latin square design. Results: We found statistical differences between eye movements towards audio-visual targets and visual targets in the absence of hearing amplification. The presence of the sound component on the stimulus improved the preparation and execution of saccades and impacted the execution of vergence. The hearing amplification has a differential impact on eye-movements towards visual targets. For vergence, it significantly reduced the amplitude of convergence. For saccades, it increased the amplitude and decreased the latency. These results could be due to an arousal state elicited by the amplifying background noise and sound coming from the participant himself. Conclusion: This pilot study opens the investigation of the different interactions between sound and saccade and vergence eye movements. We hope that these results will inspire other studies.