Many blind and visually impaired people are helped to determine the position of objects in space by special sound signals. They turned out to be much shorter than previously thought.
Echolocation is a process that allows you to determine the position of surrounding objects by the speed with which sound waves are reflected from them. By analyzing the latency rate, the brain simulates the environment around it.
This ability is best known in animals: this is how bats and dolphins orient themselves.
However, humans are also capable of using echolocation. A recent series of experiments has shown that visually impaired people are good at identifying the source of the echo. The visually impaired coped with the task of distinguishing between two simultaneous signals better than people without visual impairments.
Experts believe that training in echolocation techniques can be beneficial for blind and visually impaired people. But in order to develop methods of such training, it is necessary to understand how the echolocation mechanism works in humans. An important step towards this was taken by an international group of scientists, which included researchers from the UK, USA, China and Malaysia.
Echolocation expert Daniel Kish took part in the creation of the work. He lost his sight completely at the age of 13 months. Kish has repeatedly demonstrated his ability to navigate with the help of independently produced sounds: he rode a bicycle, went hiking and climbed mountain peaks. In the course of previous research, Kish underwent magnetic resonance imaging, which made it possible to find out which areas of the brain are activated during echolocation. Also in the new study were two more blind men who have been using echolocation for over 15 years.
Each of the participants was placed in an empty room. Men orientated themselves in their usual way with the help of clicking sounds. Scientists recorded these signals and analyzed the characteristics of their propagation and frequency range. The clicks were much shorter than previously thought: the most audible phase took about three milliseconds. According to scientists, these sounds have a more "point" direction compared to speech. The propagation of waves in this case can be compared with the directional light of a pocket flashlight.
To further study the processes of echolocation, it is necessary to attract more people with this ability. Since experienced sonars are relatively rare, the researchers synthesized the click sound used in echolocation. It will be used to simulate various situations.
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The research is published in the journal PLOS Computational Biology.
Natalia Pelezneva