August 30, 2013
Researchers Demonstrate How Echolocation Can Be Learned
redOrbit Staff & Wire Reports - Your Universe Online
Blind men and women demonstrate humans are capable of hearing more than some might realize, the research team explained. They have to learn how to navigate using the echoes of sounds they create as their guide.
“This enables them to sense the locations of walls and corners, for instance: by tapping the ground with a stick or making clicking sounds with the tongue, and analyzing the echoes reflected from nearby surfaces, a blind person can map the relative positions of objects in the vicinity,” the university said in a statement.
In their study, Wiegrebe’s team described a method they developed to train people to use sound in order to find their way around or find specific items. Using a headset that consists of a microphone and a pair of earphones, those participating in the study could generate echo patterns that simulated acoustic reflections in a virtual space.
The subject emits vocal clicks that are picked up by the microphone, and are then passed to a processor which calculates the echoes of a virtual space in a matter of milliseconds, the researchers explained.
Those echoes are played back through the earphones. The trick, they said, is that the transformation applied to the input depends on the subject’s position in virtual space, so he or she needs to learn how to “associate artificial ‘echoes’ with the distribution of sound-reflecting surfaces in the simulated space.”
According to Wiegrebe, study participants were able to locate the sources of echoes “pretty well” after several weeks of training. He said their research demonstrates anyone has the ability to “learn to analyze the echoes of acoustic signals to obtain information about the space around him.”
While blind people are forced to adapt and learn to travel using echolocation, Wiegrebe explains sighted men and women have the ability as well – only they don’t need to use those skills in everyday situations.
Rather, the perception of echoes is actively suppressed by their auditory system, allowing them “to focus on the primary acoustic signal, independently of how the space alters the signals on its way to the ears.” That allows them to make it easier to distinguish between different sound sources, focusing on the most important ones.
“The new study shows… that it is possible to functionally invert this suppression of echoes, and learn to use the information they contain for echolocation instead,” LMU officials said. The researchers plan to study how coordinating self-motion and echolocation can facilitate sonar-guided orientation and navigation in humans.
Back in May, a study led by researchers from the University of Southampton’s Institute of Sound and Vibration Research (ISVR) demonstrated how blind men and women had the potential to use echolocation, similar to that of bats, to determine an object’s location.
The study authors examined how hearing, particularly when it comes to echoes, could help blind people with spatial awareness and navigation. They also studied the potential effects of hearing impairment, as well as how echolocation could be optimized in order to improve the independence and quality of life for the visually impaired.