In 2018, a team of researchers from Duke University in the US discovered a particularly strange phenomenon: every time our eyes move, our ears produce a small beat. It’s clearly too faint to be noticed – and fortunately it would create an unbearable noise as the eyeballs move two to three times per second.
According to Jennifer Groh, lead author of this paper, the origin of this strange noise is not entirely clear. His team believes that they likely arise through two different processes. On the one hand, there are small contractions of the middle ear muscles that help muffle loud noises. On the other hand, there are hair follicles – the cells that serve as hair roots and help amplify even the smallest sounds.
Evolutionarily speaking, it would be a means to thisAdjust hearing sensitivity depending on the object being observed. Certainly an interesting observation; But it is clear that the practical use of this discovery is limited, to say the least.
Ears reveal eye movements
At least that’s how it was so far. Five years later, the same researchers finally found a way to exploit this phenomenon. According to their study published in Proceedings of the National Academy of Sciences and discovered by New Atlas, these sounds may make this possible Determine which direction the person is looking.
To reach this conclusion, the authors asked five volunteers, all of whom had good vision and no hearing problems, to offer them a simple test. Each guinea pig had to sit in front of a screen to follow the movements of a green dot while keeping its head completely still. During this time, a camera recorded the viewing direction. At the same time, an extremely sensitive microphone in the ear canal was responsible for recording those famous, imperceptible squeaks.
After the 16 volunteers completed this exercise, the researchers reviewed the data Check whether there is a direct connection between the direction of your gaze and the nature of these sounds.
And despite all odds, this unusual experience bore fruit. The researchers noticed that any vertical or horizontal movement of the eye was generated various clearly identifiable sounds. Therefore, they have combined these results into a unified model that makes this possible Determine the direction of view based on the recorded sound.
“Because diagonal movements can be divided into vertical and horizontal movements, my co-author David Murphy realized that we could combine these two components to determine what type of signal they would produce together,” explains Stephanie Lovich, co-author . – Lead author of the study. “From there we can go back in the opposite direction to determine where the person was looking, for example 30° to the left.”
Intrigued by this idea, the researchers went back to the audio recordings to try to determine the direction of gaze without using the accompanying video recording. And each time, based on that sound signature alone, they were able to determine exactly which area of the screen the volunteer was looking at.
Much more concrete applications than expected
And from there, the experience immediately became much more interesting. The researchers believe that this phenomenon could play an important role in overall perception and that this work could therefore have very concrete implications for medicine.
“If each part of the ear individually contributes to modulating the signal that reaches the eardrum, we could use these sounds as a clinical tool to determine which part of the ear is not functioning properly,” explains Lovich. The team plans to test this hypothesis by repeating the experiment with people who suffer from vision or hearing problems.
In a broader sense, dysfunctions of this mechanism could also be the cause of others Perceptual disorders that are now interpreted as neurological disorders. If it turns out that they are actually related to these noises, it may be possible to find new therapeutic ways to relieve, for example, people who suffer from dizziness or have difficulty orienting themselves in space.
The authors do not address this in their work, but with a little imagination we can also suggest other possible applications. For example, these sounds could make it possible to remotely control a device using just a pair of special earbuds.
It is therefore appropriate to follow the implications of this work, which proves that a seemingly innocuous find can lead to other, much more interesting discoveries.
The text of the study can be found here.