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Home page > Nature & Technology > Sonar Cane for the Visually Impaired

SONAR CANE for the VISUALLY IMPAIRED
Nature & Technology


Bats have inspired the production of vibrating canes to be placed at the service of the visually impaired. Plane command systems working on the same principles are also planned for development.

The particularly light electronic cane emits sound waves at a frequency (ultrasonic) too high to be detected by the human ear, and produces a three-dimensional map of the objects within a three-metre radius around it. The cane detects when there is an obstacle in its path and warns its visually impaired owner by causing buttons on the handle to vibrate. The product design belongs to Dean Waters, a research assistant at the University of Leeds and an authority on the bat. Waters states that the cane, so far tested on 25 visually impaired people, has proved to be highly successful. (1)

The cane emits 60,000 sound pulses per second and perceives the returning echoes. Buttons on the cane permit the visually impaired user to feel the intensity of the ultrasound reflections. A rapid and powerful signal means the obstacle is close by. (2)

Waters, a zoologist, staged an interesting display at a science festival in Salford near the British city of Manchester , in order to attract attention to his work. At this display the location detection system, bat sonar adapted to the human ear, was used to locate objects in a virtual reality environment. The idea here was to develop systems to make it possible for fighter pilots to control some flight systems through their sense of hearing. Pilots will thus be able to use their eyes for other tasks.

"When you drive, you can't look at the speedometer and the road at the same time, but you can listen to the radio at the same time," (3) says Waters.

Since human beings are unable to produce the high-frequency sound waves generated by the bats, Waters developed a virtual system that sends out the bat echolocation sounds and returns echoes that are reduced to a frequency capable of detection by the human ear. He placed people wearing headphones in a room and asked them to hunt a virtual insect using only the echolocation sounds. The subjects were more successful in finding their targets with bat sounds in comparison a sound source such as stereo. This difference stems from bat calls being better at producing auditory maps of space. Since the calls are short the echoes return in a very sharp form. These also possess a broadband structure, and contain both high and low frequency data. Bats are thus able to determine location more effectively. In addition, when bats approach their target the dynamically change the sounds they emit, using shorter calls as they near an object.

This superior hunting system in bats constitutes the source of both the sonar cane and the virtual location identification system. There is no doubt that this is a sign that there is a perfectly functioning design in the bat, a system so impressive as to be a source of inspiration for the very latest technology.

When we look at the sonar cane we understand that it was designed with a particular purpose in mind. We see that specific components have been specially combined in such a way as to emit sounds and identify the location of objects by detecting their reflections. These features exist in exactly the same way in the bat, the inspiration behind the sonar cane. Like other organs such as the ear and brain that work with perfect co-ordination, bat sonar is an organ that endows this creature, which hunts by night and is unable to see its surroundings, with an advantage in terms of locating its prey. Although engineers have taken bat sonar as a model, the bat did not take the idea from other living things and then develop it in its own body. It is evident that this organ, with a far more complex design than that in the sonar cane, was perfectly created.

 

NOTES
1. Joanne Baker, "Sonar cane helps blind navigate", Nature Science Update, 9 September 2003, http://www.nature.com/nsu/030908/030908-2.html
2. Joanne Baker, ibid
3. Emily Singer, "Bat echoes used as virtual reality guide", 14 September 2003, NewScientist.com

 
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