Physics does not adequately explain reflected sound and echo effects. Take as example the echo-producing Echoplex, a magnetic tape device that influenced the soundtrack of a generation. Think of Led Zeppelin’s Whole Lotta Love (1969) and the echo on its violin sections. The echo coming from Hank Marvin’s guitar shaped the sound of The Shadows in the late 1950s and 1960s. But are echoes and reverberations a passing feature of musical appreciation, limited to a generation or two? Acoustic research at a rock art site suggests not. The study site, Kurukop, is in South Africa’s Northern Cape province, in the…