In our slow change works we (I think “we”, but certainly I) wanted to allow the listener’s desensitization (caused by dense complex loud sonic experience) to subside, to create music in which our auditory cognition finds no need or trigger to be fending off, simplifying down or filtering out, which would allow the ear to perceive ever finer detail, so the listening experience would be a perceptual, and emotional, process of opening up to the sound, of increasing sensitivity to music instead of the contrary.

Back then we (or I anyway) differentiated “minimalism” from “slow change music”. The former was typically built up out of individual notes (accumulative or additive composition, e.g. Reich and Glass), and the latter tended more to be monolithic or subtractive (Radigue, some of my work, sustained tones often filtered and/or modulated, what in my own works I often though of as evolution or extrapolation processes rather than forms).

In our slow change works we (I think “we”, but certainly I) wanted to allow the listener’s desensitization (caused by dense complex loud sonic experience) to subside, to create music in which our auditory cognition finds need or trigger to be no fending off, simplifying down or filtering out, which would allow the ear to perceive ever finer detail, so the listening experience would be a perceptual, and emotional, process of opening up to the sound, of increasing sensitivity to music instead of the contrary.

It’s goal-directed motion toward goals wholly different than those familiar in Western music twixt the Renaissance and roughly the year 1900. Minimalist music also moves from one place to another with direction and purpose — just much more slowly and far more subtly than the music of the Romantic or Classical or Baroque eras.

If you doubt this, digitize a recording of Young’s Second Dream or Radigue’s Kyema and use an audio editor to speed it up by a factor of 10. You’ll hear a great deal of movement, all purposeful.

The great discovery of the minimalists remains the revelation that acoustic smoothness and acoustic roughness exhibit a hysteresis function, ditto speeding up as opposed to slowing down the musical tempo. Because of the hardwired properties of the human ear-brain system, you can perceive meaningful musical changes when you enormously decrease acoustic roughness much more readily than when you enormously increase them. Likewise, you can readily discern meaningful musical changes when you radically down the tempo of a piece than when you radically speed it up.

The properties of the human cognitive system and the human ear/brain system place sharp limits on how fast you can play a piece of music and still recognize sensible musical structures, or experience any kind of deep emotional reaction. Ditto on how much acoustic roughness you can pile up. Beyond some fast tempo or mass of acoustically rough stacked intervals, the music tends to disintegrate into a chaotic blob ‘o stuff.

There is no obvious limit, however, to how acoustically smooth you can make the vertical structures in a piece of music and still produce audible organization and emotional impact. Even if you get to extremes of acoustical smoothness, extremely slight departures from smoothness still retain a whopping dramatic impact. Likewise, there’s no obvious limit to how slow you can play a piece and still get a coherent structure or an emotional wallop from it. One composer has produced a sound installation that only repeats every 10 years.