The term is applied to radically different compositions across more than 1,000 years of history. We need a better definition.

The art of music ... if one sound produces the forward motion when the other tends to produce the backward motion, the two, if equal, will annihilate one another, and produce silence.

It’s been 50 years since Simon & Garfunkel’s “The Sound of Silence” topped Billboard ... let alone an exemplar of early folk-rock music. The two, friends from boyhood in New York City ...