Method for adjusting the frequency response of a digital filter by means of a digital signal processing device having a user interface, in particular for processing digital audio signals, comprising the steps of: - defining a desired curve of the frequency response of the filter; - calculating the taps of the digital filter so as to obtain a frequency response that approaches said desired curve, wherein the filter taps are obtained by a convolution between the taps of a first WFIR filter and the taps of a second WFIR filter, where the taps of the first WFIR filter are calculated through the steps of: - starting from the amplitude of the desired curve as a function of the frequency, generating an FIR filter using the window method, so as to obtain a sequence having a linear phase; - applying an inverse Fourier transform to the real part of the logarithm of the Fourier transform module of said linear phase sequence, so as to obtain a minimum phase sequence; - applying a WFIR filter with a warping factor -λ to said minimum phase sequence; - applying a window function to the filtered sequence, and wherein the taps of the second WFIR filter are calculated through the steps of: - starting from the desired curve, defining a cascade of second-order parametric filters; - carrying out a deformation of the frequency axis of said filter cascade, replacing each delay element, z-1, of said filter cascade with a first-order Allpass filter; - calculating an FIR filter using an impulse response truncation method for said filter cascade, so as to obtain a finite sequence; - applying a window function to said finite sequence. - defining a desired curve of the frequency response of the filter; - calculating the taps of the digital filter so as to obtain a frequency response that approaches said desired curve, wherein the filter taps are obtained by a convolution between the taps of a first WFIR filter and the taps of a second WFIR filter, where the taps of the first WFIR filter are calculated through the steps of: - starting from the amplitude of the desired curve as a function of the frequency, generating an FIR filter using the window method, so as to obtain a sequence having a linear phase; - applying an inverse Fourier transform to the real part of the logarithm of the Fourier transform module of said linear phase sequence, so as to obtain a minimum phase sequence; - applying a WFIR filter with a warping factor -λ to said minimum phase sequence; - applying a window function to the filtered sequence, - starting from the amplitude of the desired curve as a function of the frequency, generating an FIR filter using the window method, so as to obtain a sequence having a linear phase; - applying an inverse Fourier transform to the real part of the logarithm of the Fourier transform module of said linear phase sequence, so as to obtain a minimum phase sequence; - applying a WFIR filter with a warping factor -λ to said minimum phase sequence; - applying a window function to the filtered sequence, and wherein the taps of the second WFIR filter are calculated through the steps of: - starting from the desired curve, defining a cascade of second-order parametric filters; - carrying out a deformation of the frequency axis of said filter cascade, replacing each delay element, z-1, of said filter cascade with a first-order Allpass filter; - calculating an FIR filter using an impulse response truncation method for said filter cascade, so as to obtain a finite sequence; - applying a window function to said finite sequence. - starting from the desired curve, defining a cascade of second-order parametric filters; - carrying out a deformation of the frequency axis of said filter cascade, replacing each delay element, z-1, of said filter cascade with a first-order Allpass filter; - calculating an FIR filter using an impulse response truncation method for said filter cascade, so as to obtain a finite sequence; - applying a window function to said finite sequence.