Returning for a third season, NBC’s “The Sing-Off” is the most unique singing competition on television and judge Ben Folds is excited about this year’s batch of contestants. “I think this is the season of innovation,” says Folds of the field of competitors. “As [the season] evolves, I think everyone will see the innovation become second nature.”

Folds, who has been a judge for all three seasons along with Shawn Stockman of Boyz II Men, is joined this season by new judge Sara Bareilles who appeared in last season’s finale with one of the groups. “I have an a cappella background and I was a fan of the show,” says Bareilles whose hit songs include “King of Anything” and “Love Song.” “So when management brought this up to me to me that [being a judge] was even a possibility, it was a no brainer.”

Hosted by Nick Lachey, “The Sing-Off” is unlike any other vocal competition show because the singers are performing in groups using no instruments or recorded music at all. So what makes a cappella singing so interesting to watch? According to Bareilles, the style showcases the singers’ true talent. “There is nothing to hide behind,” says Bareilles. “I can’t even imagine how [the groups] are making the sounds that they make. There’s been a lot of diversity up there which is one of the things I look for.”

Folds, who is best known as both the front man of the trio Ben Folds Five as well as for being a solo artist, knows a fair share about cappella groups himself. In 2010, he released a 13-song album entitled “Ben Folds Presents: University A Cappella!” which featured different groups from colleges and universities singing a cappella versions of his songs. “I don’t know if I would listen to two hours of different groups [with instruments] and really feel moved the whole time,” he says. “There’s something about all voices that almost hits a kind of primal [level].”

As artists themselves, both Folds and Bareilles know that each singer and group will face its own set of challenges on the show. “I think [the challenge] is different for every group,” Folds says. “If you’re in an all female group, you don’t have a bass and you’ve got to find ways of making it work. And if you’re in a group of 18 guys then you might have intimacy issues. It might be difficult to find a star, one person that can act in the middle of essentially a football team.”

For her part, Bareilles is looking at skill first and foremost. “I’m looking for, first of all, technical skills, someone that’s a great singer that’s listening to their cohorts and group members and who blends well.” But that’s not all she’s looking for from a judge’s perspective. “I really like seeing diversity from the contestants. I like seeing someone that can sing jazz then flip over and sing a pop song and then sing a rock song. It’s nice to see people up there giving it their all.”

In addition to being an entertaining show, Folds hopes that “The Sing-Off” will help reignite interest and support for music education programs across the country. “That’s one of the main reasons that I got into the show,” he says about its effects on schools and administrators. “Despite the cuts [to music programs] and the de-emphasis of music in schools, you’re seeing an increased number of kids getting together on their own time. They’re having to learn harmony and voice leading with various levels of education and understanding.”

With any luck, “The Sing-Off” will not only be a hit for NBC but also a great showcase for talented singers across the country.

“The Sing-Off” premiered September 19 and airs on Mondays at 8:00 p.m. ET. on NBC.