%DEMO_DRNL  Widening of filters in the DRNL
%
%   This script displays three auditory spectrograms generated using the
%   DRNL. The input signal is the same, just presented at three different
%   levels. The purpose is to visualize the broading of the auditory
%   filters at higher input levels.
%
%   Figure 1: Greasy at 50 dB
%
%      This figure shows the DRNL of an input speech signal with a level
%      of 50 dB SPL.
%
%   Figure 2: Greasy at 70 dB
%
%      This figure shows the DRNL of an input speech signal with a level
%      of 50 dB SPL.
%
%   Figure 3: Greasy at 90 dB
%
%      This figure shows the DRNL of an input speech signal with a level
%      of 50 dB SPL.
%
%   See also: drnl
%
%   Url: http://amtoolbox.sourceforge.net/amt-0.9.5/doc/demos/demo_drnl.php

% Copyright (C) 2009-2014 Peter L. Søndergaard.
% This file is part of AMToolbox version 1.0.0
%
% This program is free software: you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation, either version 3 of the License, or
% (at your option) any later version.
%
% This program is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
% GNU General Public License for more details.
%
% You should have received a copy of the GNU General Public License
% along with this program.  If not, see <http://www.gnu.org/licenses/>.


fs=32000;
siglen=7000;
% Increase the length of the test signal to add room for the filter delay
insig=postpad(greasy,siglen);

% The three levels in dB
lvl1=50;
lvl2=70;
lvl3=90;

% Set the dynamic range for plotting.
dynrange=30;

%% DRNL 
% Change 'bwmul' to generate more channels, this make the visualization
% pretty.
[outsig1, fc1] = drnl(setdbspl(insig,lvl1), fs, 'bwmul',.1);
[outsig2, fc2] = drnl(setdbspl(insig,lvl2), fs, 'bwmul',.1);
[outsig3, fc3] = drnl(setdbspl(insig,lvl3), fs, 'bwmul',.1);

%% 'haircell' envelope extraction
outsig1 = ihcenvelope(outsig1,fs,'ihc_dau');
outsig2 = ihcenvelope(outsig2,fs,'ihc_dau');
outsig3 = ihcenvelope(outsig3,fs,'ihc_dau');

%% Lowpass filter the output for visualization and convert to dB
[mlp_b,mlp_a] = butter(2,50/(fs/2));
outsig1 = abs(filter(mlp_b,mlp_a,outsig1));
outsig2 = abs(filter(mlp_b,mlp_a,outsig2));
outsig3 = abs(filter(mlp_b,mlp_a,outsig3));

%% Visualization
ftz=20;

figure(1);
plotfilterbank(outsig1,1,fc1,fs,dynrange,'audtick');
xlabel('Time (s)','fontsize',ftz,'fontname','arial')
ylabel('Frequency (Hz)','fontsize',ftz)
colormap(flipud(bone));

figure(2);
plotfilterbank(outsig2,1,fc1,fs,dynrange,'audtick');
colormap(flipud(bone));

figure(3);
plotfilterbank(outsig3,1,fc1,fs,dynrange,'audtick');
colormap(flipud(bone));