I was asked to design a BANDPASS filter by this istruction (in Matlab): "2-stage 4th order filter with Q=4 and 12dB/octave high-pass and low-pass rolloffs". But I don't really understand what I am asked. Is this band pass made of a 4th order high pass followed by a 4th order low pass, and Q is the quality factor which defines the width of the band (how distant the two cut frequencies are) ?? And still, I would not know how to implement the 12dB rolloff in Matlab. Thanks for your help.