Glossary

dBFS

Decibels relative to full scale, the top of the digital range (0 dBFS).

dBTP

Decibels true peak: the waveform's real peak including inter-sample peaks.

LUFS / LU

Loudness units relative to full scale, and the difference between two loudness readings (1 LU = 1 dB).

PLR

Peak-to-loudness ratio: true peak minus integrated loudness.

Crest factor

Peak minus RMS level; a rougher cousin of PLR.

Gain reduction (GR)

How much a compressor or limiter is turning the signal down, in dB.

Headroom

The space between the highest peak and the ceiling or 0 dBFS.

Inter-sample peak

A peak between two samples, higher than either, that appears when the signal is converted back to analogue or resampled.

K-weighting

The filter LUFS uses to match the ear before measuring loudness.

Lookahead

A short delay that lets a limiter react before a peak arrives.

Mid/side

Splitting stereo into what is shared (mid) and what differs (side) between the channels.

Normalisation

A service turning tracks up or down to a common loudness.

Pink noise

Noise with equal energy per octave; sounds balanced, and is the reference for tonal balance.

Sidechain

Using one signal (often the kick) to control a processor on another (often the bass).