Usage:

outsig = king2019(insig,fs,basef)
[outsig, fc, mfc, step] = king2019(insig,fs,varargin)
[outsig, fc, mfc, step]= king2019(insig,fs,flow,fhigh,parameters)

Description:

Input parameter:

insig : input acoustic signal. fs : sampling rate (Hz). basef : base frequency of the analysis (Hz).

Output parameters:

king2019(insig,fs,'basef',basef) computes the internal representation around the frequency basef of the signal insig sampled with a frequency of fs Hz. outsig is a matrix of size [length fc mfc].

[outsig,fc,mfc,step]=king2019(...) additionally returns the centre frequencies of the filter bank and the center frequencies of the modulation filterbank, and 'steps' is a structure containing the intermediate model outputs.

The model consists of the following stages:

1. a gammatone filter bank with 1-erb spaced filtes.
2. a compression (exponential or broken-stick) stage applied to each individual gammatone filter. In these stages is extremely relevant to use the correct calibration level (default is dboffset = 100), given that the keyval 'compression_knee_dB' is referenced to the dboffset. Note that if other dboffset values are used (e.g., dboffset=94 dB), the knee point will in fact start compressing at higher levels.
3. an envelope extraction stage done by half-wave rectification followed by low-pass filtering to 1500 Hz.
4. a simplified adaptation stage simulated as a first-order high-pass filter
5. a modulation filterbank

Many parameters (keyvals) and flags can be optionally changed and/or switched