glossary
Integrated loudness is the long-term LUFS number most delivery checks use.
Integrated loudness measures perceived loudness across the full selected piece of audio. For a song, that usually means from the start of the master to the end of the fade.
Because it averages over time, a short loud chorus and a quiet intro both contribute to the final number.
Momentary loudness reacts very quickly. Short-term loudness smooths over a few seconds. Integrated loudness keeps accumulating across the whole measurement window.
That makes integrated LUFS useful for delivery targets, but less useful for spotting a single harsh hit or an over-limited chorus.
Start and stop the measurement consistently. Including silence, count-ins, or extra tail can change the integrated number without changing the actual mix balance.
Meter Core shows integrated, short-term, and momentary loudness together so you can see both the delivery number and the musical movement behind it.
Meter Core's integrated-loudness readings are cross-checked against FFmpeg's EBU R128 loudness measurement, using a scripted, reproducible 8-case test set covering 44.1, 48, and 96 kHz — calibrated sine anchors, filter-curve tones, a gating test program, and two full mixes. Worst-case disagreement: 0.05 LU (mean 0.03 LU).
The reading is also stable across host buffer sizes: in the archived run, a −23 LUFS calibration tone measured −23.03 LUFS at both 32- and 1024-sample I/O buffers. Method, commands, file hashes, and per-case numbers: /meter-core/accuracy/.