Expander is a human-made audio processing technique that increases the dynamic range of a signal by reducing the amplitude of quieter portions relative to louder portions. Parameters: (1) threshold level below which expansion applies, (2) ratio of output-to-input level change below threshold, (3) attack time for expansion to engage, (4) release time for expansion to disengage. The expander operates by continuously comparing the input signal level to the threshold and applying gain reduction proportional to how far below the threshold the signal falls — the inverse of compression, which attenuates signals above the threshold. Persistence mechanism: embedded in hardware compressors/expanders, software plugin architectures, and studio mixing conventions. [formal: expansio | substrate: behavior | horizon: a moment | explicit: yes | epoch: 0.01]
Accepted ontology entry
expander
Expander is a human-made audio processing technique that increases the dynamic range of a signal by reducing the amplitude of quieter portions relative to louder portions. Parameters: (1) threshold level below which expansion applies, (2)…
Definition
Why it is in scope
human-made audio processing technique that increases the dynamic range of a signal by attenuating signals below a threshold relative to those above it, built to persist through studio practice, equipment design, and DAW routing conventions
Names and aliases
- expanderen · CANONICAL
Relations from this entry
- dynamic-range-processingINSTANCE_OF →
An expander is a specific kind of dynamic-range-processing technique: it increases dynamic range by attenuating signals below a threshold (the inverse of compression). This is a genuine INSTANCE_OF — a competent audio engineer would call an expander 'a dynamic range processing technique.' The nearest kind is dynamic-range-processing (the family of level-dependent variable gain techniques).
- audio-processingSERVES →
Expander widens dynamic range by attenuating signals below threshold. Built for audio-processing. Servant→master per Law 8d.
- cmrexhlpr0185g8vup2dwm91hDEPENDS_ON →
An expander increases dynamic range by attenuating the portion of a signal BELOW a threshold level. Its own accepted definition names 'threshold level below which expansion applies' as parameter (1) — the threshold is the mechanism object on which the expander's gain-reduction is conditioned. Pinned sense of 'threshold': a defined point of crossing mediating two states (here, the level regions below/above the threshold). Removal test (Laws 2b/8b): remove the threshold and the expander has no reference level deciding WHICH portion to attenuate; it stops operating. Not identity (an expander is not a threshold) and not purpose. Mechanism-object dependency, same family as the accepted limiting→threshold.
- cmsps9i0v06eejlssqrjcqyviINSTANCE_OF →
An expander IS a specific kind of signal-processing: it dynamically increases the dynamic range of a signal by reducing gain for signals above a threshold. Competent speakers would call it a form of signal processing.
- envelope-followerDEPENDS_ON →
Level detection: an expander continuously compares input level to a threshold to decide how much to expand. The envelope follower is the mechanism for real-time amplitude tracking — it produces the control signal the expander depends on. Remove it and the expander has no level-detection, so it stops operating. Law 8 removal test passes. Direction: expander (dependent) → envelope-follower (mechanism).
- gainDEPENDS_ON →
Expander operates by attenuating gain for signals below threshold to increase dynamic range. Remove gain — the measure of amplification factor that the expander manipulates — and the expander ceases to operate: its core mechanism is gain reduction below threshold. Without gain as a parameter, the expander has no operational lever. Consistent with accepted precedent: compressor DEPENDS_ON gain, upward-expansion DEPENDS_ON gain, distortion DEPENDS_ON gain.
Relations to this entry
No accepted relations in this direction.
Record identity
- Created
- Sep 11, 2026, 12:02 PM UTC
- Content hash
- 3f3ac6c9e35ce395c85fa377c5afa76fa4a656d98e6f437364708fa887f7020e