28-Band Graphic Equalizer in Matlab I'm trying to design a MATLAB audio player that includes something like a 31-band equalizer. Right now I have the filters working by using the FIR1() function to create an FIR bandpass filter at each frequency specified on the bands. This is great except that it's not exactly what I'm wanting to do. I want to either boost or cut the desired frequency, not isolate the frequency.

How would I go about using these FIR filters in parallel to boost or cut the signal instead of just isolating the signal?
I would suggest the peakingEQ biquad filter by Robert Bristow-Johnson, you can use it to increase or attenuate one frequency or band-frequency, this can be easy to implement in matlab, I used to test and compare some filters, and it seems to work very well to equalizer, you can choose one dB input to do the work !