This Ableton tutorial walks through Vector Grain's five particle-attribute controls, showing how each one maps a physical property of a simulated particle to a specific sound parameter. Horizontal position drives panning, vertical position drives filter cutoff, and distance from center drives pitch — with an option to quantize that pitch mapping to preset scales like Octave.
Particle speed maps to loop size, so the looping section stretches and contracts as particles accelerate or slow down. Mass maps to gain, but the host immediately notices the effect is nearly inaudible because particle mass isn't varying enough by default.
The fix comes from the Particle System tab, where the Mass control lets you set a starting value for each new particle and dial in a randomization amount. Setting that randomization to maximum is what actually makes the gain mapping come alive across notes.