Seeing with Sound
From: Proto - Winter 2007 - page 29

At dusk, bats navigate through twilight, zeroing in on prey they can't see by
using pulses of ultrasound (beyond the range of human hearing) that they
generate in their larynx and send out through their nose or mouth. The bats'
highly sensitive ears then catch echoes of waves bouncing back from objects
in their path, and the bats use the timing and shape of the returning waves
to calculate the objects' positions as well as their shape and texture. This
remarkable adaptation, which enables bats to detect objects as fine as a
human hair, allows them to thrive at night, when there is less competition
for insects and other food. 

Modeling an invention on the bats' echolocation sonar, researchers at the
University of Leeds recently introduced a carbon-graphite collapsible walking
cane to aid the visually impaired. The UltraCane's handle emits ultrasonic
waves that bounce off objects as far as four meters away and send signals to
the user through two vibrating buttons on the handle. The strength of the
buttons' pulses indicates the direction, height and distance of the objects.
The same part of the brain that a bat uses to orient its movements - the
superior colliculus - helps a human process the buttons' pulses to build a
spatial map in her mind's eye of how the obstacles are arranged, allowing her
to walk more quickly and confidently than she could with an ordinary white
cane.

Links:
UltraCane
http://www.soundforesight.co.uk/index.html
http://www.atkratter.com/mobility/ultracane.htm
http://www.sense.org.uk/deafblindness/life/technology/mobility/UltraCane.htm
http://www.qac.ac.uk/enterprises/ultracane.html
http://www.ic-online.co.uk/it040001.htm

Sonar System for the Blind
http://www.qinetiq.com/home/technologies/technologies/materials/smart_materials/vibroacoustics/ultracane.html

