ITU-R BS.1770-1 (A/85:2011)

Loudness based measurement. Several filters and RMS weighting are used to get a loudness equivalent result. Starting from the well known A, B, C weighting curves (DIN-IEC 651), the ITU did further research into the relationship of frequencies, their overall levels, their peak levels and the duration of signals to develop the best representation of human loudness perception.