These definitions describe how terms are used in DecayCore. They are intentionally practical rather than exhaustive.

A-FDW

Adaptive Frequency-Domain Windowing changes analysis resolution by frequency and measurement confidence. It helps DecayCore follow broad, repeatable behavior instead of narrow reflection detail.

Convolution

The process a playback engine uses to apply an FIR impulse response to audio. CamillaDSP, Roon, and Equalizer APO can perform convolution.

Excess phase

Phase behavior left after ordinary propagation delay and the selected phase baseline are removed. DecayCore corrects it only within explicit strength and frequency limits.

FIR

A finite impulse response filter. It is stored as a sequence of samples, commonly in a WAV file, and can control magnitude and phase.

Group delay

Frequency-dependent delay. A group-delay plot helps reveal timing changes, crossover behavior, and low-frequency energy storage.

Headroom

Unused digital level reserved to prevent clipping when correction or target gain raises the signal.

HPF

A high-pass filter reduces content below its cutoff. It can protect speakers and prevent correction from demanding unsupported deep bass.

IR

An impulse response records how a system reacts over time. It contains timing, phase, and magnitude information used to design and verify correction.

Magnitude

Signal level at each frequency, normally displayed in decibels. A frequency-response graph is primarily a magnitude view.

Phase

The timing relationship of a repeating signal at each frequency. Phase correction can improve supported timing behavior, but reflection-driven phase detail must not be followed blindly.

RT60

An estimate of how long sound energy takes to decay by 60 dB. DecayCore uses reliable RT60 data as evidence and a safety constraint, not as an automatic reason to add bass.

Target curve

The frequency-response shape that guides correction. A target is a listening preference and system goal, not proof that every measured deviation can be corrected safely.

Taps

The number of samples in an FIR filter. More taps increase its time span and low-frequency resolution, but also increase processing cost and often latency.

TDC

Temporal Decay Control reduces supported low-frequency energy that lasts too long. It complements magnitude correction and does not create bass boost.

Time of flight (TOF)

The propagation delay from loudspeaker to microphone. DecayCore removes this linear delay before analyzing excess phase so distance is not mistaken for a phase error.

Verification measurement

A new measurement made with the exported filters active. It checks the real playback chain, routing, gain, crossover, loudspeakers, and room rather than only the offline prediction.