For many years, blind people have been using sounds to determine the location of objects, just like bats' sonar and the clicking that dolphins make — this ability is also known as echolocation. Now, researchers are delving deeper into how it works.

Researchers at the University of Southampton's Institute of Sound and Vibration Research (ISVR) and the University of Cyprus conducted experiments for a new study on sighted and blind people using a "virtual auditory space," a technique in which sounds are presented through headphones seem to originate from any direction. They used this technique in order to remove any positional clues unrelated to the echoes, such as footsteps or other objects, according to a press release.

The goal of the experiment was to see if participants could identify the position of an object — right or left — as well as distance and orientation. The sounds varied in bandwidth and duration (from 10-400 milliseconds), and other auditory manipulations, in order to determine which sounds the participants found most important.

"We wanted to determine unambiguously whether blind people, and perhaps even sighted people can use echoes from an object to determine roughly where the object is located," Dr. Daniel Rowan, lecturer at ISVR and lead author of the study, said. "We also wanted to figure out what factors facilitate and restrict people's abilities to use echoes for this purpose in order to know how to enhance ability in the real world."

Their results showed both blind and sighted people had potential to hear the echoes, but hearing high-frequency sounds above 2 kHz was ideal. Therefore common forms of hearing impairment would cause major problems.

"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," Rowan said. "Nevertheless, ability probably gets even better with extensive experience and feedback."

The purpose of this study, which is published in the journal Hearing Research, was to examine how hearing echoes could help blind people with spatial awareness. Researchers also wanted to understand the effects of hearing impairment in order to help improve the independence and quality of life of the visually impaired.

The researchers, however, should have looked to Daniel Kish in California.

Kish has been blind since he was a year old when the cancer, retinoblastoma, attacked his retinas. Doctors had to remove both eyes. At 44 years old, he runs the nonprofit organization World Access for the Blind, which teaches, and has already taught over 500 blind people, to use echolocation. Kish and his students say that they've never been more at peace with who they are as blind people.

Since he was a child, he had been using tongue clicks to determine the placement of objects around him, a behavior that is common in blind children among other things such as foot stomping, finger snapping, and hand clapping. Unfortunately these behaviors are deemed asocial by caretakers and the children are taught to stop, according to a March 2011 profile on Kish in Men's Journal.

"That tongue click was everything to me," he told Men's Journal.

Since he was a child, he was able to mountain bike. He can navigate streets and the forests, where he owns his own cabin, and he can tell from the front door of his house how far a car is parked from the curb.

For his thesis on the history and science of echolocation, he wrote about the first instances in which they appeared. French philosopher Denis Diderot theorized in 1749 that blind individuals could perceive objects around them before touching them through vibrations against the skin on their face. In the 1800s, the blind Englishman James Holman journeyed around the world relying on the click of his cane, but it wasn't until the 1940s that echolocation was proven scientifically in a lab by Karl Dallenbach at Cornell University.

Kish says that the National Federation of the Blind doesn't support his work.

"Let's just say he's unique," John Paré, the federation's executive director of strategic initiatives, told Men's Journal, adding that for most people he doesn't believe echolocation is worth the "tremendous effort" required to understand it. "We urge people to learn how to use a long white cane."

Another inspiring example of echolocation is Ben Underwood, featured in the video below, who was able to play basketball and ride a bicycle. His mother noticed her son's ability to "see" when she saw him get out of the street to avoid cars when playing as a child, often well before his sighted friends.

For most of his life, Kish didn't use a cane. Now he uses one on the basis that anything that will give him information about his environment is helpful. But he still believes the Federation is taking the wrong approach to treating blind people.

"The blindness field is firmly based on tradition and dogma and is very slow to evolve," he said. "It's been traditionally dominated by sighted people who feel the need to tell blind people what to do."

Source: Rowan D, Papadopoulos T, Edwards E, et al. Identification of the Lateral Position of a Virtual Object Based on Echoes by Humans. Hearing Research. 2013.

Published by Medicaldaily.com