One way to construct a graphic equalizer is by cascading several peaking/notch filters, as shown in Figure 7, where M is the number of filters. Usually the lowest and highest band filters, H1(z) and HM(z), are a low and a high shelf filter, respectively [63]. It is possible to include an optional overall gain term G0, which may be set to the average or median command gain value [63]. This helps in the cases when many command gains are set to the same value.