The Simulink model in this submission implements a 3-band parametric equalizer using a time-varying IIR filter, whose filter coefficients are generated by a S-function. This S-function implements the digital parametric equalizer design algorithm created by Sophocles J. Orfanidis.
The user inputs the desired parameters to this S-function through a convenient GUI, with which the peak gain, center frequency and the bandwidth of a band can be specified. Dragging and moving the colored markers or the colored lines in the GUI changes the filter parameters.
Please change the name of the WAV file in the "From Wave File" block to the name of your own .wav file in the path, or you could also use the 'From Wave Device' block in Signal PRocessing Blockset to run it with sound from sounds card.
Reference: S. J. Orfanidis (1997), "Digital parametric equalizer design with prescribed Nyquist-frequency gain," Journal of the Audio Engineering Society, vol. 45, num. 6, pp. 444-55.
Thanks to Dick Benson for modifying the original version to make it more robust.