Recent research from Duke demonstrates that eardrum oscillations or movements start slightly before the brain directs movement of your eyes (called saccades). This indicates that motion in the eyes and ears are controlled by the same motor commands deep in the brain. The eardrum changes are thought to occur from middle-ear muscles tugging on the eardrum. The movement begins 10 milliseconds before the eyes start to move and continue for a few tens of milliseconds after the eyes have completed their movements.
To understand the sensory information (vision and sound), our brain needs to coordinate what we see and what we hear according to where the object and sound are coming from. The eyes and brain are doing this differently. The eyes are giving you a picture of the visual scene (hopefully a 3-D picture if your eyes are working well together), but for sounds, your brain has to calculate where the sounds are coming from based on differences in timing and loudness across the two ears. Researchers think the eyes and ears moving together like this enables the brain to put the information together accurately and efficiently.
The researchers are unsure if these eardrum movements are the most important aspect of the phenomenon or if there is more to the interactions. Also under investigation is how the vibrations impact what we hear and the role it could play in hearing disorders. Answers to these questions may aid in improving hearing aids. Future studies will explore if up and down (vertical) eye movements also cause unique signatures in eardrum vibrations.
In our clinic, we use the auditory system (for example, a metronome) to aid in developing oculomotor skills. This information gives support to why this would be an effective way to develop those skills. It is simply fascinating to gain more insight into the complex and detailed way that our brain works! For us, it is just proof that vision is involved so importantly in so many functions of our body!
Journal reference: bioRxiv, DOI: 10.1101/156570