Envelope following maps smoothed audio amplitude over time to continuously control visual parameters

Interactive audio systems need to extract meaningful control signals from complex sound. Envelope following computes a smoothed average amplitude over time, producing a value that rises when the sound gets louder and falls when it quiets. Attack detection sets an amplitude threshold: when the signal crosses it, a trigger fires. This is used to synchronise visual events with percussive sounds. Pitch tracking estimates the fundamental frequency of a harmonic sound, enabling computer response to a musician’s notes. Score following uses pitch and timing analysis to advance through a pre-written score without relying on a fixed clock.

Examples

// Pseudo-code for attack detection: if (amplitude > threshold && !wasAbove) { triggerVisualEvent(); wasAbove = true; } else if (amplitude < threshold) { wasAbove = false; }

Assessment

Design an audio-reactive visual sketch where a circle’s size follows the audio envelope and a flash occurs on each percussive attack; specify what threshold and smoothing values you would test first.