457374.fig.0012a
(a)
457374.fig.0012b
(b)
457374.fig.0012c
(c)
457374.fig.0012d
(d)
Figure 12: Magnitude frequency responses of the digital filters in the ARA equalizer: (a) the first-order Butterworth highpass filter, (b) the biquad peak filter, (c) the biquad notch filter, and (d) the combined response of the three filters.