phasing

Phasing was developed by Steve Reich in the mid-1960s after he accidentally played two identical tape loops simultaneously and noticed them gradually falling out of sync due to slight speed differences. He formalized this discovery into a compositional technique: two performers play the same repeating pattern in unison, then one gradually accelerates until they are one beat ahead, creating a constantly shifting kaleidoscope of rhythmic relationships before eventually returning to unison. Reich's early phasing works — It's Gonna Rain (1965) for tape and Piano Phase (1967) for live performers — demonstrated the technique's extraordinary generative power. As the patterns shift, entirely new melodies and rhythms emerge from the interference patterns between the two voices, like acoustic moiré patterns. The technique influenced not only minimalist composition but also electronic dance music production, where phasing effects are routinely used to create evolving textures.