4.1. Bands in Graphic EqualizersThe basic unit of the graphic equalizer is the band. A graphic equalizer typically has morebands than a parametric equalizer. The bands are usually distributed logarithmically in frequency,to match human perception. Let us denote the normalized lower and upper crossover frequencies ofthe mth band with ωl,m and ωu,m respectively. Bandwidth is the difference between the upper andlower crossover frequencies, Bm = ωu,m − ωl,m. The frequency bands are adjacent [52], so the uppercrossover of band m will be the lower crossover of band m + 1, ωu,m = ωl,m+1. That is, input audiofrequencies below this crossover will be primarily affected by the gain control for band m, whereasinput frequencies above it will be primarily affected by the gain control for band m + 1.