Humans’ Bat-Like Sonar Could Help the Blind

Bats use echolocation to navigate in the dark when hunting prey. (Steve Garner via Creative Commons/Flickr)

Humans have built-in biological sonar similar to bats and dolphins that could lead to a better quality of life for blind people and the visually impaired.

The international study suggests people have the ability to use echoes, or echolocation, a skill some animals  use to detect and find objects. Developing this ability could promote increased independence  for the blind and visually impaired.

The study, published in Hearing Research, looked at how the ability to hear echoes could help the blind with spatial awareness and navigation. Researchers also examined the impact hearing impairment has on echolocation as well as how to optimize a person’s echolocation capabilities.

Using a technique called virtual auditory space, which creates sounds that simulate movement, the researchers from the University of Southampton and the University of Cyprus, conducted a series of experiments with sighted and blind subjects.

“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. 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,” said Daniel Rowan, the study’s lead author.

The researchers found that, as long as they have good hearing, both those with and without sight have the potential to use echoes to locate objects, even if they have no previous experience with echolocation.  The study found that individuals must be able to hear high-frequency sounds – above 2 kHz – to effectively use echolocation.

Illustration of how a bat uses echolocation to find prey (Shung via Wikimedia Commons)

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

Rowan also adds, “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. While our experiments purposely removed any influence of head movement, doing so might help extend ability to farther distances. 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 study authors plan to extend their research to explore the use of echolocation to find objects in three-dimensional spaces.

They also want to examine why some blind people appear to be better at using this technique than others, including people who can see.