A single beat starts from silence, a tenor voice comes in with a sort of sweet sadness. Suddenly a bass comes in and accompanies the single voice. Then, with the repetition of “When the lights go down/ in the middle of the night,” a new voice comes in, creating a beautiful three-part harmony. Then an anthem for all those lost in this world rings out: “In the middle of the night,/ I’ve been running, running, running/ And I’m on my way home.”

This is the newest offering from Pentatonix, the country’s No. 1 a cappella group, on their groundbreaking new album “PTX, Vol. III.” Tight vocals and breathtaking tracks such as “Standing By” and “Papaoutai” have proven that the five members of Pentatonix — Scott Hoying, Mitch Grassi, Kirstie Maldonado, Avi Kaplan and Kevin Olusola — are here to stay.

Having created the entire album during its world tour earlier this year, the group seems to have taken much of what it learned on the road and applied it to its music. The entire album has a world music feel to it, with the addition of tribal chants in “On My Way Home” and folk-rock styling in “Standing By.” Their lyrics also reflect lessons they learned on the road such as being away from people they love with songs like “Rather Be,” “Standing By” and “On My Way Home.”

The covers on this album are some of the best the group has put out. Tracks “La La La” by Naughty Boy and “Latch” by Sam Smith are merged together in “La La Latch,” where Pentatonix creates a fun song with a catchy chorus. It mixes the two songs so well, listeners may have trouble telling which line is from which song, prompting them to put this song on repeat in order to analyze its many parts.

As always with Pentatonix, there is the one, novel track on the album that has proven that, musically, it hasn’t stopped trying to surprise listeners. “Papaouti,” a cover of a song from singer-songwriter Stromae, features Hoying on the lead vocals, with all the lyrics sung in French. Lindsey Sterling, world-renowned violinist, and Olusola are featured in the song on violin and cello, respectively, ultimately crafting an exciting track that, with the help of the two added instruments, may leave listeners feeling an intensity that is hard to come by in the a cappella industry.

From the fun of “La La Latch” to the heartfelt sadness in the lyrics of “Standing By,” Pentatonix has offered up the best sort of twists and turns that the music industry can offer.