NEW RESEARCH FROM the University of Southhampton has shown that blind and visially impaired people have the potential to use echolocation, similar to that used by bats and dolphins, to determine the location of an object.
The study, which was published in the journal Hearing Research, examined how hearing, and particularly the hearing of echoes, could help blind people with spatial awareness and navigation.
It also examines the possible effects of hearing impairments on optimising the echolocation ability in order to help improve the independence and quality of life of people with visual impairments.
Researchers conducted a number of experiments with both sighted and blind listeners to investigate how the distance and orientation of a reflective object affected their ability to identify whether it was on their right or left.
Audio manipulation
They used sounds with different bandwidths and durations as well as various audio manipulations to investigate which aspects of the sounds were important.
The ‘virtual auditory space’ where they were conducted allowed researchers to remove positional clues unrelated to echoes, such as footsteps and the placement of an object, and to manipulate the sounds in ways that wouldn’t be possible otherwise (eg get rid of the emission and present the echo only).
The results showed that both sighted and blind people with good hearing, even if completely inexperienced with echolocation showed the potential to use echoes to tell where objects are. The researchers also found that hearing high-frequency sounds (above 2 kHz) is required for good performance, and so common forms of hearing impairment will probably cause major problems.
Training programmes and assistive devices
Some people are better at this than others, and being blind doesn’t automatically confer good echolocation ability, though we don’t yet know why, Dr Daniel Rowan, lead author of the study said. “Nevertheless, ability probably gets even better with extensive experience and feedback.”
“We also found that our ability to use echoes to locate an object gets rapidly worse with increasing distance from the object, especially when the object is not directly facing us,” he said.
“Furthermore, some echo-producing sounds are better for determining where an object is than others, and the best sounds for locating an object probably aren’t the same as for detecting the object or determining what, and how far away, the object is.”
The knowledge gained from this study will help researchers to develop training programmes and assistive devices for blind people and sighted people in low-vision situations. The team is also extending their research to investigate finding of objects in three-dimensional space and why some blind people seem to be able to outperform others, including sighted people.
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