President Eisenhower is in office, and the modern form of rock & roll is beginning to emerge. Don’t tell the Chordettes that, though. The mostly a cappella performances of “Mr. Sandman” and “Lollipop” by the Sheboygan harmonizing girls—Janet, Alice, Lynn, and Jinny—wowed the radio. In this live TV performance, the Chordettes, who are frequently likened to a barbershop quartet, show...