• by Wayne Friedman , December 14, 2010

TV shows with a sudden rise in viewership are rare these days: NBC now has one of those in "The Sing-Off." 

The second-year limited series "Sing-Off," an a cappella group competition program, has been on a tear lately. Monday night's performance rose sharply, up nearly 20% to a Nielsen preliminary 3.3 rating/10 share among 18-49 viewers. The previous week, its second season debut, was at a 2.8 rating.

All this was on top of a 22% gain from a year ago, when it posted a 2.3 rating in its season debut and a 2.3 rating in its season finale -- typically the two biggest episodes of a reality competition show. In between, the series had a dip in ratings.

For NBC, the numbers added to glimmers of good fortune -- at least on the reality genre front.

On Monday, the network announced a new reality singing competition show, "The Voice of America" -- to be launched next spring and produced by successful and veteran reality producers Mark Burnett of "Survivor" and "Apprentice" fame, and John de Mol, producer of "Big Brother" and "Fear Factor." The show aims to go after Fox's "American Idol" and its new competition show produced by Simon Cowell, "The X Factor."

On Monday, NBC lifted its fortunes from a week ago to a 2.6/7 from a 2.4. But it still couldn't catch Monday night leader CBS, which saw its strong comedy lineup rise to a 3.5/9 from a 3.3 rating.

CBS' "Two and a Half Men" grew to a 4.4/11 from a 4.2 rating a week ago at 9 p.m. -- the best-performing show of the night. "Mike & Molly" put on three-tenths of a rating point to a 3.7/9.

Some of CBS' and NBC's gains may have come from lackluster competition, particularly ABC. "Skating with the Stars" continued to suffer, now down to a 0.7 rating/2 share among 18-49 viewers -- a 30% drop from its rating the previous week. After that. ABC's "Mariah Carey: Merry Christmas to You" dropped to a low 1.1 rating/3 share.

Fox also witnessed growth this week -- running a better-viewed lineup of "House" (2.4 rating/6 share) and "Lie To Me" (1.9 rating/5 share) repeats versus fresh programming of "American Country Awards" (1.5 rating) of a week ago. For the night, Fox was at a 2.1 rating/5 share versus its 1.5 rating of a week ago.