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);

- Input arguments:
- a_tilde : Complex filter constant gamma_filter_order : Gammatone filter order fs : Sampling rate fc : Centre frequency a_tilde : Complex filter constant bandwidth_factor : Bandwidth factor, default value is 1.0 bw : Filter bandwidth (in Hz)

`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.