South Africa, June 8 -- It is just past seven on a Tuesday morning in Durban. The minibus taxis are already packed, conductors hanging from sliding doors, calling out stops to the morning rush. Inside, the bass hits before the doors close.

The sound is a heavy, syncopated thud that seems to come from somewhere primordial, yet the tracks were made last night in a backroom in KwaMashu on a cracked laptop running Fruity Loops. The older woman on the pavement refuses to get in. She calls it noise. The rest of the world, it turns out, calls it Gqom, and they cannot get enough of it.

Spotify's numbers make for startling reading. Since 2018, global streams of Gqom have grown by 5,732 per cent. Peak listening hits every Saturday between 5pm and...