Time is growing short for the boy who "sees" with sound.

Ben Underwood, the blind teenager who has dazzled people all over the world with his ability to navigate using a tongue-clicking skill called echolocation, is getting weaker day by day.

The cancer that took his eyes when he was a toddler has returned with a vengeance, invading his brain and his spinal cord. Ben's legs no longer are strong enough to support him, and his mother must carry him up and down the stairs of their Elk Grove home. The teenager who traveled the globe the past two years giving inspirational speeches and impressing people with his ability to get around in a world he cannot see, spends most of his time these days in a hospital bed in the living room, sleeping, praying and listening to music.

Ben is under the care of hospice nurses, and he understands what that means. But he insists he is not afraid of dying, even at the tender age of 16. One day soon, he told his mother, Aquanetta Gordon, he simply will go to sleep and wake up in heaven.

"He is such a strong kid. He never complains," Gordon said on a recent day, as Ben slept nearby under a fuzzy blue blanket. "I am the one who cries. The idea of having to bury my baby? I'm not sure how to do this."

Ben's doctors said he could have weeks, or months, to live. But whenever the end comes, he will have left a powerful imprint.

Since The Bee published his story in May 2006, Ben has been featured in magazines, newspapers and television programs from Japan to Great Britain. He gave an inspirational speech to some 10,000 people at a Christian conference in Hawaii and has become an Internet sensation. He has chatted with Oprah Winfrey and danced with Ellen DeGeneres on national TV. He has become friends with the iconic musician Stevie Wonder, who celebrated his 16th birthday with him and slipped into town quietly again last week for a visit.

"Ben is an extraordinary young man who has inspired literally millions of people," said his doctor, Kaiser Permanente pediatric oncologist Kent Jolly. "He has fought a heroic battle."

Blind since he was a toddler, when a cancer called retinoblastoma took both of his eyes, Ben adapted remarkably well. He taught himself to reach places safely by counting steps and by using his keen senses of hearing, smell and touch. Gordon insisted that her son attend mainstream schools and be treated no differently from his classmates. She encouraged him to take risks.

When he got older, Ben taught himself to identify objects by making clicking noises with his tongue, creating sound waves that he uses to identify objects and get around. The skill, called echolocation, is commonly seen in bats and dolphins but rarely documented in humans.

Thanks to his spirit and his incredible navigational skills, Ben has been able to take part in all of the rituals and activities of childhood and adolescence.

He has attended mainstream schools, most recently Sheldon High, and has refused to use a white cane identifying him as blind. He's played basketball, practiced karate, skated and ridden a bike through his Elk Grove neighborhood, clicking his tongue and listening for sound waves that tell him whether he is facing a brick wall, a metal car or other obstacles. He's learned to type 60 words per minute and text message his friends. He's played video games by memorizing scenarios and identifying sounds that characters make before they move or strike.

Jolly and Ben's pediatric ophthalmologist, James Ruben, said they have never met anyone quite like him.

"It's extraordinary that Aquanetta has raised him without treating him as if he was disabled, and Ben has risen to the challenge," Jolly said. "He's never been allowed to cut corners or take it easy or feel sorry for himself."

Ben's cancer was in check until 2007, when he developed a tumor in his sinus cavity. Intensive chemotherapy, radiation treatments and experimental measures have failed to cure it, Jolly said.

The teen continues to get radiation treatments that keep him more comfortable, but the effects are temporary, said Jolly. Ben dislikes taking pain medication, but gets some relief when his mother gently massages his head and shoulders.

Her son is aware that his time is running out, Gordon said, and he accepts his situation, though he has not talked much about it. "After the doctor told us what was going on, I asked Ben, 'Are you afraid to die? Are you scared? Do you need me to hold you?' " she said. He told her that he had no fear, and that he looks forward to seeing her in heaven.

"He's totally at peace," Gordon said. "My strength comes from him."

In recent weeks, as Ben has become weaker, his many friends have been spending long hours at his bedside. They rub his hands and feet, fluff his pillows and play his choice of music on the stereo in the living room. Some of his favorite tunes are songs from a gospel rap CD that he created. The project is not quite finished. Maybe Stevie Wonder will take up the task, Gordon mused.

"Ben has always been a kid I could rely on," said Gordon, who has four other children, ages 13 and up. "Always responsible. Always taking care of business.

"I only get him for a moment. I won't get to see him get married or have a family or go to college.

"But Ben's life wasn't just for me. It was to share with the world. Now Ben is dying in a graceful way. That's part of his purpose, too."

Call The Bee's Cynthia Hubert, (916) 321-1082.