K-weighting is the frequency-weighting curve at the heart of modern loudness measurement, defined in ITU-R BS.1770. Before a meter integrates a signal into a loudness number it passes it through this two-stage filter: a high-shelf boost that approximates the acoustic effect of the head, plus a high-pass that rolls off the lowest frequencies the ear weights less. The result tracks perceived loudness far better than a flat reading, and it is the 'K' in LKFS. Every loudness target you meet — EBU R128's -23, ATSC's -24, streaming's about -14 — is a K-weighted, gated measurement. It is deliberately simple and standardized so every compliant meter agrees.
The book · Volume 4 of 7
Audio for Video: A Complete Guide to Sound in Video Products: From PCM and Codecs to Loudness, Accessibility, and Real-Time Voice Processing
K-weighting is why a LUFS meter and your ears agree more often than a peak meter does, and why bass-heavy mixes can read quieter than they sound. Volume 4 covers it in detail with LUFS, loudness standards, true peak and dynamic range, so you can trust your loudness readings and set targets per platform. Written by Nikolay Sapunov, CEO at Fora Soft.
Loudness readings don't match what you hear, and you suspect K-weighting?
Share sample mixes and your delivery targets, and we will measure them, explain the readings and send normalization settings per platform. 250+ video products shipped since 2005.
