DETROIT - Art Garfunkel said his voice is "slowly coming along" and predicted that he'll be able to hit the road again with Paul Simon soon -- possibly even before the end of the year.

"Late 2011 -- I feel in my bones, in my cells, that that's the scenario," Garfunkel told Billboard.com during a conversation about the duo's just-released "Bridge Over Troubled Water: 40th Anniversary Edition." "Give me a little more time. At the rate the voice is coming back, I should be in pretty good shape by, as the corporations say, the fourth quarter of 2011."

No dates have been booked yet, however.

Simon & Garfunkel scratched a series of North American dates on their Old Friends tour in 2010 after Garfunkel was diagnosed with vocal cord paresis. Since then he's been healing with vocal exercises, steam, gargling and other treatments, including voice warm-up tapes sent to him by friends.

"I'm being challenged by the Lord to have patience, real patience," Garfunkel said. "It's coming along slowly, painfully, excruciatingly slow. I try and stay off the subject and not bemoan anything. But I'm never going to give up on my crusade to return to the stage...I swear to you we'll do those dates."

Simon -- who's releasing a new album "So Beautiful or So What," on April 12 and touring to support it starting April 15 -- is solidly in Garfunkel's corner "in the nicest, sweetest way. He knows you don't want to press anything; healing is about relaxing. He called me a few weeks ago and said, 'When you're ready, I'm very happy to bring the guitar around the house and let's try 'The Boxer,' let's warm up, let's see where we're at. So he's definitely rooting seriously for me...It shows you the core of Simon & Garfunkel is a thing of beauty."

So, Garfunkel said, is "Bridge Over Troubled Water," the 1970 release that spent 10 weeks at No. 1 on the Billboard 200, spawned four Top 20 hits ("The Boxer," "Cecilia," "El Condor Pasa (If I Could)" and the title track), has gone eight-times platinum and won five Grammy Awards.

"It's alive and well," Garfunkel said of the set. "It's not one of those albums that's faded in its glory. It's a record that's full of variety... Each new tune comes out of left field compared to the one before it. That's why it continues to appeal to people, I think."

Garfunkel is particularly happy with the DVD that comes along with the 40th anniversary edition of the album, which includes a new documentary, "The Harmony Game: The Making of Bridge Over Troubled Water," as well as "Songs of America," a controversial CBS TV special that aired on November 30, 1969, and has remained in the vaults ever since.

"I've been loving it for years," Garfunkel said, "because it's got sort of a liberal political stance. It's got teeth, and it's so of-the-time that I thought it has innate appeal. And I thought any fan of ours is going to really see the vibe between Simon and Garfunkel, how we hung out, how we riffed with our Lenny Bruce sense of humor in the back of a car and how songs developed sitting on the end of a bed in the Holiday Inn. You can see how Paul and Artie go together. It's innately interesting."

While he's healing his voice, Garfunkel has also been working a book, a memoir of sorts that he says is "coming along" and will deal with all aspects of his life. "I've been cooking along... being poignant, getting the reader to feel touched, like, 'This guy's got something to say," Garfunkel noted.