# Peaking filter (loudness) cutoff frequency in an equalizer

An equalizer we have consists of Loudness ,Bass ,Mid and Treble .The loudness is nothing but a Peaking filter with cutoff frequency 20Hz .I read this in a book that outlines the EQ design. I was wondering why the Loudness block which is basically a Peaking Filter should have a cut off frequency of 20Hz ?? Any intuition behind this