I don't think the visuals were derived directly from the audio track played with them in the film. The article has a good description:

> [Stokes’] procedure was to cut a tape recorded melody into short segments and splice the resulting pieces into tape loops. The audio signal from the first loop was sent to a radio transmitter. The radio waves from the radio transmitter were confined to a tube and focused up through a glass slide on which he had placed a chemical mixture. The radio waves would interact with the solution and trigger the formation of the crystals. In this way each slide would develop a shape interpretive of the loop of music it had been exposed to. Each loop, in sequence, would be converted to a slide. Eventually a set of slides would be completed that was the natural interpretation of the complete musical melody.