function stimulus = sig_kolarik2010(c_innerbw,c_flanking_phase,c_noise_mode,c_tone_level,c_itd,c_sphase,fs,dur,cos_rise_time,bw,fc,spl)
%sig_kolarik2010   Tone masked by a diotic inner-band and two antiphasic flanking-band noises
%   Usage: stimulus = sig_kolarik2010(c_innerbw,c_flanking_phase,c_noise_mode,c_tone_level,c_itd,c_sphase,fs,dur,cos_rise_time,bw,fc,spl)
%
%   Input parameters:
%
%     c_innerbw: bandwidth of diotic noise band centered at target frequency (in Hz)
%
%     c_flanking_phase: IPD of flanking-band noises
%
%     c_noise_mode: 1 for a single-delayed noise, 2 for opposingly delayed noises (known as double-delayed noise)
%
%     c_tone_level: tone sound pressure level (in dB)
%
%     c_itd: interaural time difference(s) of the inner-band noise (in s)
%
%     c_sphase: IPD of target tone
%
%     fs: sampling rate (in Hz)
%
%     dur: duration of stimulus (in s)
%
%     cos_rise_time: duration of the cosine ramp at start and end of signal (in s)
%
%     bw: overall bandwidth of stimulus (in Hz)
%
%     fc: center frequency of inner band and target tone (in Hz)
%
%     spl: spectral sound pressure level of noise (in dB)
%
%   SIG_KOLARIK2010 creates a tone masked by a diotic inner-band 
%   and two antiphasic flanking-band noises.
%
%   See also: eurich2022 exp_eurich2022
%
%   References:
%     A. J. Kolarik and J. F. Culling. Measurement of the binaural auditory
%     filter using a detection task. The Journal of the Acoustical Society of
%     America, 127(5):3009--3017, 05 2010. [1]arXiv | [2]http ]
%     
%     B. Eurich, J. Encke, S. D. Ewert, and M. Dietz. Lower interaural
%     coherence in off-signal bands impairs binaural detection. The Journal
%     of the Acoustical Society of America, 151(6):3927--3936, 06 2022.
%     [3].pdf ]
%     
%     References
%     
%     1. http://arxiv.org/abs/https://pubs.aip.org/asa/jasa/article-pdf/127/5/3009/14776306/3009\_1\_online.pdf
%     2. https://doi.org/10.1121/1.3365314
%     3. https://pubs.aip.org/asa/jasa/article-pdf/151/6/3927/16528275/3927_1_online.pdf
%     
%
%   Url: http://amtoolbox.org/amt-1.5.0/doc/signals/sig_kolarik2010.php


%   #Author: Bernhard Eurich (2022): original implementation
%   #Author: Piotr Majdak (2023): Documentation updates

% This file is licensed unter the GNU General Public License (GPL) either 
% version 3 of the license, or any later version as published by the Free Software 
% Foundation. Details of the GPLv3 can be found in the AMT directory "licences" and 
% at <https://www.gnu.org/licenses/gpl-3.0.html>. 
% You can redistribute this file and/or modify it under the terms of the GPLv3. 
% This file is distributed without any warranty; without even the implied warranty 
% of merchantability or fitness for a particular purpose. 

spar.innerbw = c_innerbw;
spar.itd = c_itd;
spar.noise_mode = c_noise_mode;
spar.fs = fs;
spar.dur = dur;
spar.cos_rise_time = cos_rise_time;
spar.bw = bw;
spar.spl = spl;
spar.fc = fc;
spar.sphase = c_sphase;
spar.tone_level = c_tone_level;
spar.innerbw = c_innerbw;
spar.flanking_phase = c_flanking_phase;
spar.nlcut = 0; % lower freq limit of masker
spar.nhcut = 2500; % upper
spar.bandshift = [0.5]; % downshifted, centered, upshifted
spar.innernotch_db = [0]; 

% this function generates the stimulus for the experiment from
% Kolarik & Culling 2010  (as simulated in Fig. 5 in Eurich et al. 2022)

%%%%%

% tone
tone_mono = gen_tone(spar.fc,spar.dur, spar.fs,0);
tone      = [tone_mono spar.sphase*tone_mono]; 
tone_spl  = set_dbspl(tone,spar.tone_level);

len = spar.dur * spar.fs;

[window] = cosine_fade_window([1:spar.dur*spar.fs]', spar.cos_rise_time, spar.fs);



spar.nlcut = spar.fc - spar.innerbw*spar.bandshift; %floor(spar.fc-spar.bw/2); % noise
spar.nhcut = spar.fc + spar.innerbw*(1-spar.bandshift);


% freq spacing
fftpts = spar.fs; % length 1ms for now, truncated later
spacing = spar.fs/fftpts; % 1 Hz spacing

% nyquist freq bin, depending on even or odd number of samples
nyBin = floor(fftpts/2) + 1;

% vector of freq per bin up to Nyquist freq
freqVec = [0:nyBin-1]' * spacing;

% lowest and highest bins
% lower flanking noise
lbin1 = 1; %
hbin1 = min( round(spar.nlcut/spacing), nyBin );

% higher flanking noise
%     correction = spar.innerbw==0; % so that in case of no inner band we don't double the middle bin
lbin2 = max( round((spar.nhcut)/spacing) +1, 2); % + 1 so that the edge bin isn't contained twice
hbin2 = min( round(spar.bw/spacing), nyBin );

% inner noise
lbin3 = max( round((spar.nlcut)/spacing) + 1, 2);
hbin3 = min( round(spar.nhcut/spacing), nyBin );

% create Gaussian white noises
a1 = zeros(fftpts,1);
b1 = a1;
a2 = zeros(fftpts,1);
b2 = a2;
a3 = a2;
b3 = b2;
a4 = a2;
b4 = b2;

% noises for each real and imag part: lower/upper flank, twice SDN
% real parts
a1(lbin1:hbin1) = randn(hbin1-lbin1+1,1);
a2(lbin2:hbin2) = randn(hbin2-lbin2+1,1);

if hbin3 - lbin3 >0 % only if bins are different, noise is generated here --> scale bins if notch
    a3(lbin3:hbin3) = randn(hbin3-lbin3+1,1) * 10^(-spar.innernotch_db/10);
end

% Nu
a4(lbin1:hbin1) = randn(hbin1-lbin1+1,1);
a5(lbin2:hbin2) = randn(hbin2-lbin2+1,1);


% imag parts
b1(lbin1:hbin1) = randn(hbin1-lbin1+1,1);
b2(lbin2:hbin2) = randn(hbin2-lbin2+1,1);
if hbin3 - lbin3 >0
    b3(lbin3:hbin3) = randn(hbin3-lbin3+1,1) * 10^(-spar.innernotch_db/10);
end

% Nu
b4(lbin1:hbin1) = randn(hbin1-lbin1+1,1);
b5(lbin2:hbin2) = randn(hbin2-lbin2+1,1);


% complex noise spectra
fspec1 = a1+ 1i*b1;
fspec2 = a2+ 1i*b2;
fspec3 = a3+ 1i*b3;
fspec4 = a4+ 1i*b4;
fspec5 = a5+ 1i*b5;

fspec1_shift = fspec1;
fspec2_shift = fspec2;
fspec3_shift = fspec3;


% phase shifts flanking bands
if (hbin1-lbin1 >= 1) && (hbin2-lbin2 >= 1)
    if isequal(spar.flanking_phase,pi) % pi0pi condition
        fspec1_shift(lbin1:hbin1) = fspec1(lbin1:hbin1) .* exp(1i*spar.flanking_phase);
        fspec2_shift(lbin2:hbin2) = fspec2(lbin2:hbin2) .* exp(1i*spar.flanking_phase);%
        
    elseif isequal(spar.flanking_phase,99) % u0u condition: independent noise
        fspec1_shift(lbin1:hbin1) = fspec4(lbin1:hbin1);
        fspec2_shift(lbin2:hbin2) = fspec5(lbin2:hbin2);
    elseif isequal(spar.flanking_phase,pi/2) % pi0pi condition
        
        fspec1_shift(lbin1:hbin1) = fspec1(lbin1:hbin1) .* exp(1i*spar.flanking_phase);
        fspec2_shift(lbin2:hbin2) = fspec2(lbin2:hbin2) .* exp(1i*0);%
    end
end


% phase shifts inner band: if flanking phase = pi, inner band phase = 0 and vice versa
inner_phase = 0; % for KolCul10 inner phase always 0
fspec3_shift(lbin3:hbin3) = fspec3(lbin3:hbin3) .* exp(1i*inner_phase);

fspec_l = fspec1 + fspec2 + fspec3;
fspec_r = fspec1_shift + fspec2_shift + fspec3_shift;


noise_flanked_l = (2*real(fftpts*ifft(fspec_l)))/std(2*real(fftpts*ifft(fspec_l)));
noise_flanked_r =  (2*real(fftpts*ifft(fspec_r)))/std(2*real(fftpts*ifft(fspec_r)));
noise_flanked   = [noise_flanked_l noise_flanked_r];

noise_flanked_spl = set_dbspl(noise_flanked,spar.spl + 10*log10(spar.bw));




% add tone to noise
stimulus = tone_spl + noise_flanked_spl(1:len,:);


end




function [signal_out] = set_dbspl(signal_in,dbspl_val)
%set_dbspl set SPL for each signal channel
% SIGNAL_OUT = set_dbspl(SIGNAL_IN, DBSPL_VAL)
% SIGNAL_IN     preassure waveform, multi channels in colums
% DBSPL_VAL     level in dB SPL (ref value is 20e-6 pa), per chanel
%
% see also get_dbspl, add_dbgain, audio_signal_info


p0 = 20e-6; %ref value

val = sqrt(mean(signal_in.^2));

factor = (p0 * 10.^(dbspl_val / 20)) ./ val;

signal_out = signal_in .* factor;

end

function [window] = cosine_fade_window(signal, rise_time, fs)
%cosine_fade_window returns a weighting vector for windowing (fade-in + fade-out) a signal
%WINDOW = cosine_fade_window(SIGNAL, RISE_TIME, FS)
% SIGNAL    preassure waveform, multi channels in colums
% RISE_TIME time in seconds
% FS        sampling frequency
% WINDOW    vector with the length of SIGNAL
%
%           ................
%        .                    .
%     .                          .
%  .                                .
% |rise_time|              |rise_time|
% |          signal_time             |
%
% EXAMPLE:
%       fs = 48e3;
%       sig = generate_tone(100,.5,fs);
%       window = cosine_fade_window(sig,.1,fs);
%       ramped_sig = sig .* window;

n_ramp = round(rise_time * fs);
n_signal = size(signal,1);

window = ones(1, n_signal);
flank = 0.5 * (1 + cos(pi / n_ramp * (-n_ramp:-1)));
window(1:n_ramp) = flank;
window(end-n_ramp+1:end) = fliplr(flank);
window = window';

end


function [sine,time] = gen_tone(frequency, duration, fs, start_phase)
% gen_tone returns a cosine wave
% [SINE, TIME ] = gen_tone(FREQUENCY, DURATION, FS, START_PHASE)
% FREQUENCY     frequency in Hz
% DURATION      duration in seconds
% FS            sampling frequenc
% START_PHASE   default is 0
% SINE          sine wave
% TIME          time vector for the cosine-wave
%
% see also getAMS gen_sam audio_signal_info
if nargin < 4
    start_phase = 0;
end

nsamp = round(duration * fs);
time = get_time(nsamp, fs);

sine = cos(2 * pi * frequency * time + start_phase);

end

function [time] = get_time(signal, fs)
%get_time returns time-vector for a given
% signal or number of samples
%[TIME] = get_time(SIGNAL, FS)
% SIGNAL    signal or number of samples
% FS        sampling frequency
% TIME      time vector (start with 0)
%
% see also nsamples

dt = 1. / fs;

if length(signal) > 1
    nsamp = length(signal);
else
    nsamp = signal;
end

max_time = nsamp * dt;

time = 0:dt:(max_time - dt);

time = time';
end