Sunu has developed a wristband that emits a silent, high frequency sound and vibration to alert the visually impaired of obstacles within their environment. (Jhaan Elker/The Washington Post)

Watching Fernando Albertorio stroll down a crowded sidewalk in downtown Washington during a recent lunch hour, casually sidestepping pedestrians running errands and crowding around food trucks, you’d have no idea he is legally blind.

Albertorio easily blends into the flow of human traffic swirling around him, which is even more remarkable considering that he is doing so largely without the use of his limited vision.

His secret: a wristband called Sunu that emits a high-frequency sound wave that bounces off objects as far as 14 feet in front of him before registering as a gentle, pulsing vibration on his arm.

The closer the object is — whether it’s a wall, trash can or person — the more frequent the pulses become, allowing Albertorio to create a mental map of the world around him using echolocation. He compares the device to sonar being used in vehicles to sense nearby objects and avoid crashes.

Albertorio, who grew up in Puerto Rico, is part of a team of entrepreneurs from Mexico who built Sunu from scratch and are hoping their invention changes the way visually impaired people get around.

“One of my friends calls the device his ‘sixth sense,’ ” Albertorio said, noting that people with vision loss are sometimes afraid of going outside. “It enhances my awareness of my personal space and keeps me safe when I’m out in my neighborhood.”

For the visually impaired, smartphone apps can help them hail a ride, link to real-time maps and get to the nearest convenience stores. But avoiding a tree branch obstructing a sidewalk after a storm or walking through a busy, rush-hour crowd, not to mention finding an office in an unfamiliar building or locating the closest restaurant in a new neighborhood. There is no app for that.

It was those challenges — the kind that can fill an ordinary day with physical hazards and extreme complication — that led Albertorio to develop Sunu.

“This is a way of getting people outside and doing things while being discreet,” he added. “Folks want to be able to go outside, be active, blend in and be part of their community.”

The device’s settings, including range and sensitivity, can be customized using the company’s app.

The National Federation of the Blind estimates that there are more than 7 million people living with visual disability in the United States. Some experts expect that number to increase sharply in the coming decades as baby boomers reach old age and are afflicted by glaucoma and other eye diseases.

Although the visually impaired are still largely reliant on guide dogs and the white cane — a tool that is nearly 100 years old and doesn’t protect users above their knees — the Sunu band isn’t the first device to harness the power of echolocation. Inventors have created vibrating clothing that uses echolocation and a vibrating clip that uses ultrasound to help visually impaired people avoid obstacles above their lower body.

And at least one man, known as “the real-life batman,” trains visually impaired people to create a rudimentary form of echolocation by clicking his tongue against the roof of his mouth — a tactic he learned on his own. By clicking, Daniel Kish, who lost both eyes to cancer as a toddler, is even able to ride a bike on city streets.

The challenge for engineers, Albertorio said, is creating technology that isn’t obtrusive, distracting the user from the sensations and sounds visually impaired people rely upon. A vibrating cane might help a user detect large obstacles ahead of them, for example, but it can also numb the delicate sensations that allow someone’s fingertips to perceive subtle changes on the ground below, Albertorio said.

Because of the variety of navigational challenges visually impaired people face, there is no single solution for getting around, experts say. Having access to a portfolio of complementary navigational tools is often ideal, according to Dave Power, the president and chief executive of Perkins School for the Blind,  the first school for the blind in the United States. 

“If you’re walking down the sidewalk and you’re anticipating a corner, it’s hard to beat a guide dog that knows you and can help you travel long distances,” he said. “But if you drop your wallet on the floor, you might prefer using Sunu over using a cane, which might be a clunkier solution for finding a small object.”

In the future, Albertorio said he’d like to link innovations like Sunu with Google Maps or Facebook, so that a visually impaired person could point a device in different directions to get up-to-date information about complicated urban environments, such as business areas, parks, offices or transportation locations. Instead of being tethered to their routine routes, Albertorio said, such a device would allow visually impaired people to roam freely.

“What we’re really creating is technology that augments human awareness, and this is just the beginning,” he said.

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