NBC's "The Sing-Off," hosted by multi-platinum recording artist Nick Lachey, returns for its fourth season Monday, Dec. 9 (9-11 p.m. ET).

The season will run for seven episodes, with the two-hour finale set for Monday, Dec. 23 (8-10 p.m. ET/PT). The groups, who are competing for the prize of $100,000 and a Sony Music recording contract, will perform for celebrity judges Jewel ("Two Hearts Breaking" "Ring of Fire") Ben Folds Ben Folds Five) and Shawn Stockman ( Boyz II Men ).

The 10 groups that will vie to be the best a cappella group in the country were revealed today. The announcement was made today by Paul Telegdy, President, Alternative and Late Night Programming, NBC Entertainment. They are:

ACOUSTIKATS (Lexington, KY): This collegiate group has been serenading sorority girls all over the University of Kentucky campus, but now it's their time to make it on the big stage. With their southern charm they hope to win over America's hearts.

CALLE SOL (Aguadilla, Puerto Rico): From the island of Puerto Rico, this group of six professional musicians has only been together for a few short months. Their Latin style is sure to bring a flare to the competition.

ELEMENT (New York City): This all-female group brings a New York attitude to the stage. They all work day jobs and pursue their showbiz dreams in the concrete jungle during their time off. These powerful female voices hope to bring a buzz to the a cappella world.

THE FILHARMONIC (Los Angeles): This locally based group is made up of male Filipino singers. Their knack for '90s R&B, mixed with their Filipino culture, is sure to bring a new twist to the music of the past.

HOME FREE (Minneapolis): This all-male group has already been on the road touring the country and the transcontinental journeys have made them all very close. Their years of performance experience add to their refreshing country sound.

THE PRINCETON FOOTNOTES (Princeton, N.J.): A 50-year-old tradition is holding strong with this Ivy League group - classically trained, perfectly polished and technically great. Although they stick to tradition, they also like to mix a modern flair.

STREET CORNER RENAISSANCE (Los Angeles): This soulful group put aside their dreams of becoming musicians to raise their families. Now it's time to shine. Their roots are in doo-wop and they strive to pay homage to this classic sound.

TEN (Dallas): Many of these eclectic artists have experienced traveling with professionals in well-known bands. Their group leader brought them together. The gospel influence and impressive backgrounds produce a perfected sound.

VOCAL RUSH (Oakland, CA): The youngest group in the competition is a force to be reckoned with. They have won the high school a cappella groups' international championship two years in a row. Their pop and R&B influence are sure to put a spin on modern chart-topping hits.

VOICEPLAY (Orlando, FL): These three best friends have been together since high school and expanded their group to six, added the influence of a female voice. They toured the U.S. and ended up back in Orlando performing before auditioning for "The Sing-Off." This pop-inspired group blends the male and female voices perfectly.

Music from season four of "The Sing-Off" will be available on iTunes the day of each telecast.

"The Sing-Off" scours the country in search of the best a cappella groups who will perform chart-topping songs in weekly competition. The groups will be competing for America's vote and a chance to walk away with the ultimate prize: A Sony Music recording contract and $100,000.

A new twist will be added this season. At the end of every show, the bottom two groups decided by the judges will Face Off in an Ultimate Sing Off, trying to knock their opponent out of the competition with the power of only their voices. At the end of the night, one group will be eliminated from the competition. One song, two teams, with their dreams on the line.

"The Sing-Off" is produced by One Three Media (a Hearst/Mark Burnett company) along with Outlaw Entertainment and Sony Pictures Television. Mark Burnett (NBC's "The Voice"), Deb Newmyer, Sam Weisman

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