In the shadow of Angkor Wat, Cambodia, a place that houses some of the oldest temples on Earth, people, young and old and considered deaf, came by the hundreds looking for a miracle.

Bill and Tani Austin of Eden Prairie, Minn., were there in November to prove that most weren't deaf at all. They say 95 percent of the world's so-called deaf are merely hearing impaired but can do nothing about it.

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For 10 months a year, the couple travel around the world to fit the hearing impaired with hearing aids. Last year, the Austins' Starkey Hearing Foundation fit 165,000 free hearing aids for people in India and the Bronx, from New Orleans to New Guinea.

During the visit to Angkor Wat, Tani Austin fit Sarien, 12, with powerful hearing aids to see whether she could get her to respond. Her mother said she was completely deaf. With the hearing aids on, though, Sarien could hear sounds and tried desperately to make sounds for the first time in her life.

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"Hearing is very emotional," Tani Austin said . "It's the road to the heart."

After Bill Austin got rich running the hearing aid company Starkey - the industry's only US owned and operated one since 1967 - he made it his mission to spend the money by giving back. He started the foundation in 1984 with wife Tani. Starkey supplies the hearing aids.

Their goal: help 1 million people to hear by 2020. So far, nearly 500,000 hearing aids have been distributed around the globe.

"For me a day here is better than any day on any beach anywhere in the world. It's better than any fine meal in Paris. I would stay here and not eat at all and work for these kids and go home tired and say I had a good day," Bill Austin said.

ABC News was there in Angkor Wat as more than 400 faces heard sounds for the first time in their lives.

"What you're seeing is hope. Mothers are the same all over the world. They want education for their children. They want safety in their homes. They're hoping to have a better life for their child," said Tani Austin.

The Austins send families home with a year's worth of batteries and local contacts for help too. There are no strings attached.

"It's the best job ever," Tani Austin said, "because it never gets old."

For more information on the foundation, click here .