Mr. Cavett’s wide-eyed Everyman schtick worked wonders when introducing to a heartland audience a jittery, cane-wielding David Bowie in a 1974 show in which Mr. Bowie rattled on about “black noise,” a concept promoted by the subversive novelist William Burroughs about a hypothetical sonic frequency that is effectively a “noise bomb,” with which “you can crack a city or people.”

“Let’s not give the instructions,” Mr. Cavett said, barely containing a smile.