2025-05-09

control and variation

modulation systems and parameter shaping

envelopes

envelopes are piecewise functions that shape parameter trajectories over time. they define how a control value evolves during an event.

types

  • start-to-end: transitions from a defined start value directly to a defined end value.
  • zero-to-zero: begins and ends at 0, useful for isolated modulation arcs.

segments

  • attack: ramp up from 0 to peak.
  • attack-bend: curved (non-linear) rise.
  • decay: ramp down from peak to sustain level.
  • decay-bend: curved (non-linear) fall.
  • hold: sustain at a fixed level.

decoration apply sinusoidal modulation to envelope segments for added texture, e.g.:

  • amp (amplitude)
  • amod (amplitude-modulation depth)
  • frq (frequency)
  • fmod (frequency-modulation depth)

sequences

sequences are ordered collections of values or control points used for parameter curves, event scheduling, or data processing.

path interpolation

define a control path by a list of tuples (x, y, c), where:

  • x = time or index
  • y = value
  • c = curvature or tension for interpolation

random

  • distributions: choose values from uniform, gaussian, etc.
  • random path points: scatter values stochastically.
  • repetition: repeat or reseed the random process.

patterns

  • integer partitions: split a total length into varied segments.
  • segment partitions: divide a sequence into named sections.
  • combinations: select subsets of values or indices.
  • deduplication: remove duplicate entries.
  • filtering: classify and keep values satisfying criteria.
  • gaps: insert rests or zero-values.
  • sorting: reorder values ascending or descending.
  • nesting (abstraction): group sequences hierarchically.
  • interpolation: fill in missing or intermediate values.
  • rotation: cyclically shift the sequence.
  • seamlessness: ensure end-to-start continuity.
  • alternation: interleave multiple sequences.
  • mapping & preset-selection: replace values via a lookup or select predefined sequences.

modifications

  • swap: exchange two elements.
  • reverse: invert the order.
  • arithmetic: add, remove, multiply, or divide individual values.

instrument classification

in digital additive synthesis, instruments can be categorized along several orthogonal dimensions to guide design, selection, and composition.

continuity

  • continuous: sounds that can sustain indefinitely once triggered

    • short: brief sustained tones (e.g. plucked strings with rapid decay)
    • long: fully sustained tones (e.g. bowed strings, wind drones, organ pads)

  • non-continuous: sounds composed of discrete events

    • pitched: percussive or struck instruments with definite pitch (e.g. piano, marimba)

    • unpitched: percussive noise hits without clear pitch (e.g. drums, clicks, snaps)

sound origin

  • natural: emulations or samples of real-world phenomena

    • wind, water flow, rain drops, insect swarms

  • effects: designed sound events for texture or transition

    • cracking, impacts, metallic reflections, ambience sweeps

functional role

  • melodic: primarily carries pitch-based melodies
  • harmonic: provides chordal support or sustained harmonic pads
  • percussive: drives rhythm with transient attacks
  • ambient/textural: creates evolving backgrounds and atmosphere