On their fifth album, Straight No Chaser boldly take a cappella music from the barbershops of yesteryear to the pop charts of today. The well-oiled ensemble gleefully make over recent hits by The Weeknd, Taylor Swift, Pharrell, and Hozier, along with more evergreen entries from the likes of Radiohead, Otis Redding, and CCR. They’re at their most playful with “The Movie Medley,” which embraces pure comedy, but the group’s flawless harmonizing and R&B-trained vocals yield an emotional impact that emphasizes sincerity over novelty.