Portland’s Michael Odokara-Okigbo and the Dartmouth Aires are apparently not always pitch-perfect.

For the first half of this season on NBC’s “The Sing-Off,” the show’s judges couldn’t find anything to criticize about Odokara-Okigbo and his a cappella group. Week after week the group was praised for its stage presence, its energy and its vocal precision.

But Monday’s episode marked one of the first times the judges detected problems – mostly minor ones – with the group’s performance.

“There were little flubs here and there, harmony-wise,” judge Shawn Stockman said of the group’s rendition of the country song “Save a Horse, Ride a Cowboy” by Big & Rich. “But it was energized and fun.”

“The groove and the bottom end were a little loose, but I think you guys pulled it back together,” said singer Ben Folds, another judge. “Watching you guys is like watching a Broadway show.”

The third judge, singer Sara Bareilles, said the group may have concentrated too much on putting on a “big” number and could sometimes let the arrangement get “a little loose.”

The problems weren’t enough to convince the judges to send the Dartmouth Aires home – the group advanced to the next round and will sing again on next Monday’s show.

Now Odokara-Okigbo and the Dartmouth Aires are one of just five groups left vying for the grand prize of $200,000 in cash and a Sony Music recording contract, out of the 16 groups that started the season.

The show’s grand prize – which could start the winning group on the way to a career in pop music – will be announced on the season finale Nov. 28.

Odokara-Okigbo, a graduate of Waynflete School in Portland and a former member of the Boy Singers of Maine, is currently a senior at Dartmouth College in Hanover, N.H.

The Dartmouth Aires began Monday’s episode by singing a required rock song, “We’re Not Gonna Take It” by Twisted Sister. Odokara-Okigbo sang one of the two leads with high energy, kicking his legs at the camera and pumping his fists.

Before the performance, Odokara-Okigbo had said on camera that being on the show convinced him he wanted to pursue a music career.

Stockman, one of the judges, was perplexed that Odokara-Okigbo had ever considered not singing for a living.

“Michael, what were you going to do outside of singing?” Stockman asked him. “You seem so natural up there. That was a great performance.”

Staff Writer Ray Routhier can be contacted at 791-6454 or at: [email protected]