A cappella group Pentatonix offers powerful vocals in their takes on top 40 hits

Pentatonix, the winners of the third season of the NBC show 'The Sing-Off,' showed they're more than a YouTube sensation at a sold-out concert at Boston's House of Blues.

From “cello beat-boxing” to an interactive audience sing-along, vocal group Pentatonix had no problem amping up the crowd at their recent sold-out concert at the House of Blues in Boston.

The five-person a cappella group, which was the winner of the third season of NBC’s “The Sing-Off,” are not your average YouTube sensation – they’re better.   

With Scott Hoying’s spot-on solos, Mitch Grassi’s unreal high notes, Avi Kaplan’s sultry bass, Kirstie Maldonado’s pitch-perfect diva vocals and Kevin Olusola’s beat-boxing/percussion perfection, the group is a unique mix of individual voices that beautifully blend into one.

It’s so perfect that it’s almost robotic, too good to be real – but it is.

What was once just popular among “choir nerd extraordinaires” (as Hoying called himself and some of his fellow group members during the concert), a capella music has transformed into a pop culture phenomenon, partially due to shows such as "The Sing Off" and "Glee" and even more recently with films such as "Pitch Perfect" (which made over $100 million in the box office) and ABC Family's "The Mistle-Tones." Pentatonix has scored YouTube hits in the millions and currently boasts about 230,000 Facebook fans and more than 71,000 Twitter followers. 

In a time where people glorify electronic beats and synthesized vocal chords – such as those remixed by Swedish DJ Avicii - and synthesized vocal tracks - such as top-of-the-charts songs like Carly Rae Jepsen's "Call Me Maybe" – Pentatonix offers a refreshing twist to top 40 hits.

With little choreography and only some minor light effects (different colors for different songs, spotlights on individual group members, etc.), the group stayed away from a flashy routine and kept the performance simple but still fresh to avoid simply replicating their YouTube videos.

Highlights of the show:

– The combination of Kaplan's hilarious jokes/one-liners and body roll dance moves (seriously, how did he move his legs like that?) was highly entertaining, not to mention when he sang a song originally from “The Hobbit" titled "Misty Mountains Cold."

“I don’t know what I was doing in Middle Earth at the time, but I’m sad I missed out,” Kaplan said to the crowd.

– Olusola's "cello beat-boxing" was also a standout. Olusola is beyond talented – he's a Yale graduate, fluent in Chinese and can literally provide a beat for anything, even a cello. Hoying said they got Olusola on board after seeing a YouTube video of him cello beat-boxing, which is basically playing the cello while simultaneously beat-boxing. Yes, it’s as impressive as it sounds.

– Pentatonix proved they have more than covers up their sleeve by performing a new number, “Peaceful World,” written by Kaplan. The song showcased all of the group’s amazing ranges and vocal talents – it was a little slow, but it left me wanting more of their originals. Here’s to hoping some of the originals include Olusola’s amazing cello beat-boxing.

– An 'N Sync medley was one of the best parts of the show. While I’ve watched Pentatonix’s Youtube rendition before, seeing it in person brought my inner 10-year-old to life. 

– Olusola and Kaplan said audience participation is their favorite part about every concert because they love getting the crowd to sing along. First they divided the audience into three sections – Team Scott, Team Kirstie and Team Mitch. Then the less musically talented were assigned clapping roles. Everyone had a part to play. Then Olusola and Kaplan beat-boxed and dropped the bass. I have to say, we didn’t sound half-bad. Maybe Pentatonix should take us on tour as their back-up singers. (Just kidding, they don’t need back-up anything.)    

– After the band “ended” their show with Nicki Minaj’s “Starships,” the crowd started chanting “PTX” to get an encore. After a few minutes, the group came back on stage and performed their last few fan favorites. First came Florence and the Machine’s “Dog Days Are Over,” with Grassi hitting some impressive high notes. Then came a YouTube favorite, a cover of fun.'s “We Are Young." Pentatonix's version has over 7 million hits.

Now that the concert is over, I am eagerly anticipating the group’s new album. Until then, I’ll have to keep my inner acanerd occupied with YouTube covers.

Saba Hamedy is a Monitor contributor.