There's a simple explanation for teen singer Billy Gilman's absence from the spotlight. He isn't in rehab, and he isn't rebelling by suddenly releasing a punk album. Billy's been on hiatus because, like other 15-year-old boys, he's waiting for his voice to change. "It was very frustrating to go through this process," says Billy, whose hit "One Voice" launched the then-10-year-old's career in 2000. "Even knowing that it was coming, I had no idea that it would take this long to complete." However, Billy hasn't been on complete voice rest. The growing performer recently sang for Celine Dion in Las Vegas at Caesars Palace. Billy also did two live casino shows to sold-out crowds. "I can't wait to get back in the studio and make new music," says Billy, who might enter the studio later this year. "Even though I'm still very young in this business, I feel that my experience over the last five years will help me make the best record of my career."