Keyboard pioneer Robert Moog alleged that "electronic music is the hot-rodding of the '90s." Anyone who watches Iara Lee's Modulations is likely to believe it.

A documentary love letter to the processed beat, Modulations explores the myriad genres and micro-niches of the electronic subculture: techno, trance, house, jungle, hip-hop, triphop, ambient, etc. It's a heady mixture, and Lee jumps from subject to subject at a pace that's as propulsive and artfully frenzied as a rave. We get John Cage rhetorically asking "What is music?," DJ Spooky expounding on the importance of history, and Squarepusher waxing rhapsodic over his favorite toy synthesizer.

The thesis behind this superabundance of material is one of evolutionary change. Modulations illustrates above all the collision of varying influences and their hybrid children. Afrika Bambaattaa combined the innovative synth drones of Kraftwerk with the urban rap of the Bronx to create the electro-funk sound. Juan Atkins exploded the Detroit scene by combining techno with dance. And the collective rave scene—hyper-fueled by ecstasy—gave birth to jungle, which is in itself a combination of dub, techno, et al.

At once a primer, think-piece, and prediction of musical futures, Modulations charts a revolution in sound that is as unstoppable as it is constantly changing.