The Oak Ridge Boys' background as a gospel quartet gave them a unique edge when the group reoriented themselves as a country unit in the '70s. The foursome staked their sound on rich vocal harmonies, whether they were tapping into a Cajun flavor on "Leaving Louisiana In the Broad Daylight," or a leading a homey barroom stomp on "Y'all Come Back Saloon." And their honky-tonkin' 1981 hit “Elvira” showed just how low their voices could go, with that bellowing, subterranean “ooh-papa-mow-mow” hook.