gfb_filter_new(a_tilde,gamma_filter_order); gfb_filter_new(fs,fc,gamma_filter_order,bandwidth_factor); gfb_filter_new(fs,fc,bw,attenuation_db,gamma_filter_order);
gfb_filter_new(a_tilde,gamma_filter_order) specifies the complex filter coefficients directly.
gfb_filter_new(fs,fc,gamma_filter_order,bandwidth_factor) computes filter coefficient from sampling rate, center frequency, and order of the gammatone filter. The filters will have 1 ERB equivalent rectangular bandwidth, times bandwidth_factor. Filter coefficient are computed from equations (13),(14)[Hohmann 2002].
gfb_filter_new(fs,fc,bw,attenuation_db,gamma_filter_order) Computes the filter coefficients from the sampling rate, center frequency, the desired bandwidth with respect to the given attenuation, and the order of the gammatone filter. Filter coefficient are computed as in equations (11),(12)[Hohmann 2002] (section 2.3).
V. Hohmann. Frequency analysis and synthesis using a gammatone filterbank. Acta Acustica united with Acoustica, 88(3):433-442, 2002.