The Human Brain "Sees" with Sound Waves!
A recent scientific study revealed that echolocation, known among bats and dolphins, is not exclusive to them; humans possess the same ability and can learn it with relative ease, although achieving a professional level is more complex. Researchers explained that leading experts in this field use mouth clicks or cane taps to build a precise mental map of their surroundings, even in complete darkness, enabling them to determine the location, size, distance, shape, and even the material composition of objects.
The study, conducted by researchers at the Smith-Kettlewell Eye Research Institute in San Francisco, USA, provides the first detailed description of how the human brain accomplishes this task. The results showed that the central nervous system gradually builds its representation of the environment with each returning echo, refining it over time, relying not on a single echo but on a sequence of successive sounds.
In the experiment, researchers compared the performance of four professional echolocation experts with that of 21 sighted participants who had no prior experience in this field. During the sessions, electroencephalography (EEG) caps were placed on the participants, who listened in a dark room to a series of artificial clicks followed by simulated echoes mimicking sound reflection off a virtual object, and were asked to identify its location.
- Professional experts demonstrated significantly higher accuracy than chance in almost every trial.
- The performance of sighted participants did not exceed 50 percent, equivalent to random guessing.
- Three experts who lost their vision early in life stood out with superior performance, correctly identifying the location with an accuracy exceeding 70 percent, even after hearing only a few clicks.
Researchers noted that early blindness may enhance the brain’s sensitivity to sound, pointing out that the optimal angle for brain performance was approximately 45 degrees from the midline. They also observed that each returning echo stimulated spatial brain networks at a faster rate than the previous one, which may reflect the speed at which sensory information is extracted, integrated, and refined.
The study, supervised by a specialized research team, was published in the journal eNeuro. It is among the first studies to use EEG to track how the human brain processes echolocation information click by click, providing additional evidence of the remarkable plasticity of human sensory perception systems in the absence of vision.
