By Tracy Kornet, CBS 11 News

RICHARDSON (CBSDFW.COM) – Most patients suffering from Parkinson’s disease eventually lose their ability to talk and swallow. But a new therapy offered here in North Texas is being called “miraculous” by many of those who have had their lives impacted by the disease.

Parkinson’s disease can be cruel, but you would never know that after hearing the singers from The Texas Voice Project. All of them have Parkinson’s disease, but a cutting-edge therapy has helped them get their voices back.

“We specialize in a treatment called the Lee Silverman Voice Treatment,” explained Samantha Elandary, the founder and executive director of The Texas Voice Project. “It’s a project that actually has been around for 23 years.”

Of those with Parkinson’s disease, 89 percent are at high risk of losing their ability to speak or swallow. “If it’s not treated, the voice gets softer and softer and softer,” Elandary said.

Jerry McMahan was diagnosed with Parkinson’s disease three years ago. “My voice was getting weaker. I was losing quality of voice. I wasn’t able to articulate as well as I used to be able to,” he said. “I was starting to have problems with my throat.”

But thanks to The Texas Voice Project, McMahan has seen dramatic improvements in every area. “Being able to speak louder. Being able to have more control over my breathing,” he explained. “I think exercising the vocal chords helped with swallowing.”

The strict, intense therapy sessions are all conducted by licensed speech pathologists. They last one hour, four days a week for four weeks. And the success rate is staggering. Of the 450 patients that have tried the therapy, Elandary said, “We were able to help all of them except one.”

But, perhaps the most stunning part of The Texas Voice Project, is that treatment is free. “We want to give every Parkinson’s patient the opportunity to receive this treatment,” Elandary said. Those who can afford it are asked to make a donation, however, in hopes that patients will ‘pay it forward’ and the next generation of patients can join the chorus of hope.

Click here to get more information on the therapy program. And to see the therapy’s results firsthand, you can watch the choir perform on Saturday morning at 11:00 a.m. at the Eisemann Center for the Performing Arts in Richardson. A panel discussion with some top Parkinson’s disease experts will be held after the performance. Tickets cost $25. Call 469-375-6500 for more information.