Pentatonix continues to redefine a cappella music

Here are two of the most common reasons music listeners either refuse to listen to a cappella music or are quickly bored by it: 1) It's almost always covers of popular songs, and 2) It's difficult to keep arrangements of songs as interesting as music with actual instruments. In its self-titled fourth album, Pentatonix, a five-person a cappella group and the 2011 winner of NBC's "The Sing-Off" (2009 - present), remedies both of these issues.

Members Scott Hoying, Kirstin Maldonado and Mitch Grassi started off as high school friends who liked to sing. They wanted to audition for "The Sing-Off," but the show requires auditioning groups to have at least four members. The trio soon discovered bassist Avi Kaplan and beatboxer and cellist Kevin Olusola. The group, which met for the first time just the day before auditions for "The Sing-Off," went on to win the competition and is now arguably the biggest name in a cappella.

Pentatonix made history this month when its newest release became the first a cappella album to hit the number one spot on the Billboard 200 chart. Released Oct. 16, "Pentatonix" features mostly original songs, though the deluxe version includes several covers. 

"Pentatonix" opens with three of the album's best songs. "Na Na Na," the first track, begins with Grassi's smooth vocals accompanied by clapping in the background. There is no way to avoid dancing to this song; it's catchy and upbeat, and the background harmonies and runs are tight.

"Can't Sleep Love," a fan favorite since its release as a single in September, has a funky R&B vibe that is anchored by Kaplan's groovy bass line. One of the biggest challenges of transitioning to all-original music is creating original lyrics. With lines like "Somebody wake up my heart / Light me up / Set fire to my soul," "Can't Sleep Love" makes clear that Pentatonix doesn't have too much of a problem with this switch.

With an infectious chorus and even a rap from Olusola, "Sing" is another dance-worthy number, which is made evident in its official music video. Each member of the group has a chance to shine on the song, which can't be said for some of the remaining tracks on the album.

The album only continues to impress with "Ref," which peaks during its catchy chorus. Maldonado gets her own solo in the second verse, reminding listeners that though Hoying's voice is undoubtedly incredible, the entire group is talented. One of the downfalls of the album is how heavily it focuses on Hoying. He is lead vocalist on 10 of the 13 songs, while Grassi leads on four, Maldonado two and Kaplan and Olusola on one apiece. This lineup clearly disproportionately favors the main vocal trio (Hoying, Grassi, Maldonaldo) which will delight Hoying's fans but will disappoint those who want to see the range that Pentatonix has to offer.

There are a few songs on the album that aren't so memorable -- two of these are Kaplan ("Light in the Hallway") and Maldonado's ("Water") only solo songs, which is unfortunate. Both songs are pretty, but don't stand out as among the greatest on the album. The same can be said for "Rose Gold," which has some disjointed, minimalist rhythms that don't quite work anywhere except the chorus. "Take Me Home," a softer song, is, however, probably the best slower song on the album; it is focused on pure vocals, which is a nice change of pace.

The only cover on the standard version is "If I Ever Fall in Love," a cover of Shai's version from 1992, featuring Jason Derulo. If anyone had any doubt that Derulo, the same singer most people associate with "Talk Dirty" (2014) and "Wiggle" (2014) can sing, those doubts will surely be erased after listening to this cover. From the start of this track, listeners know it will be great; Derulo's and Hoying's velvety tones are enough to make anyone a little weak in the knees. Derulo hits high notes with surprising ease and, during the breakdown, belts an incredible sounding G#5. Be on the lookout for collaborations in the future, because Derulo and Pentatonix are a golden combination.

This album has put Pentatonix on the map and will no doubt entice fans of all musical genres. It could even appeal to those who swore that they were sick and tired of all the a cappella.