Rockapella Sings Nostalgic a Capella

What is it about a cappella pop groups that makes their spirit so playful? AsRockapella, an influential ensemble since the early 1990s, performed a sleek set of oldies at Feinstein’s/54 Below on Friday, the show became the musical equivalent of watching the members of a basketball team happily toss a ball around. Camaraderie and comedy go together; there’s something essentially lighthearted about human voices imitating instruments.

The sound of this group, which achieved fame on the PBS series “Where in the World Is Carmen Sandiego?,” is a nostalgic pastiche of post-doo-wop, post-Motown vocal styles infused with jazz harmonies that doesn’t aspire to mechanical precision. Its show, “Hits Like You Never Heard,” was loose-jointed and audience friendly to the extent that the group coaxed a shy audience member to join it for a performance of “Stand by Me.”

The lineup, which has changed over the years, now includes the high tenor Scott Leonard, the group’s chief songwriter and arranger; the tenors Steven Dorian and Calvin Jones; the vocal percussionist and human beat box Jeff Thacher; and Ryan Chappelle, its bassist and newest member. The concert was so rhythmically animated that in places you could almost swear they were singing along to tracks. The most impressive moments were solo turns by Mr. Thacher and Mr. Chappelle.

The opening number, “Rock Around the Clock,” established the nostalgic tone of an evening that continued with “Jailhouse Rock” and included many Motown classics; the most contemporary reference was a fragment of Macklemore and Ryan Lewis’s “Thrift Shop.” Mr. Leonard mused out loud about the all-but-invisible line between pop jingles and pop songs.

In an evening of pure entertainment, the missing ingredient was emotional gravity. The Temptations’ hit “Just My Imagination,” a ballad about loneliness and dreaming, was pallid. In the harmonies of a group devoted to evoking fellowship and good times, there is little, if any, room for introspection.