Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Add CAR biquad design to other/car/matlab #15

Open
wants to merge 1 commit into
base: master
Choose a base branch
from
Open

Add CAR biquad design to other/car/matlab #15

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
73 changes: 73 additions & 0 deletions other/car/matlab/CAR_Design.m
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,73 @@
% Copyright 2023 The CARFAC Authors. All Rights Reserved.
% Author: Matt R. Flax, setup taken from Richard F. Lyon's CARFAC_Design.m
%
% This file is part of an implementation of Lyon's cochlear model:
% "Cascade of Asymmetric Resonators with Fast-Acting Compression"
%
% Licensed under the Apache License, Version 2.0 (the "License");
% you may not use this file except in compliance with the License.
% You may obtain a copy of the License at
%
% http://www.apache.org/licenses/LICENSE-2.0
%
% Unless required by applicable law or agreed to in writing, software
% distributed under the License is distributed on an "AS IS" BASIS,
% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
% See the License for the specific language governing permissions and
% limitations under the License.

function [CF, b, a] = CAR_Design(n_ears, fs, CF_CAR_params)
% function CF = CAR_Design(n_ears, fs, CF_CAR_params)
%
% This function designs the linear open loop CAR (Cascade of Asymmetric
% Resonators) as biquadratic filters.
% That is, it take bundles of parameters and
% computes all the filter coefficients needed to run it.
%
% fs is sample rate (per second)
% CF_CAR_params bundles all the pole-zero filter cascade parameters

if nargin < 1
n_ears = 1;
end

if nargin < 2
fs = 22050;
end

if nargin < 3
CF_CAR_params = struct( ...
'velocity_scale', 0.1, ... % for the velocity nonlinearity
'v_offset', 0.04, ... % offset gives a quadratic part
'min_zeta', 0.10, ... % minimum damping factor in mid-freq channels
'max_zeta', 0.35, ... % maximum damping factor in mid-freq channels
'first_pole_theta', 0.85*pi, ...
'zero_ratio', sqrt(2), ... % how far zero is above pole
'high_f_damping_compression', 0.5, ... % 0 to 1 to compress zeta
'ERB_per_step', 0.5, ... % assume G&M's ERB formula
'min_pole_Hz', 30, ...
'ERB_break_freq', 165.3, ... % 165.3 is Greenwood map's break freq.
'ERB_Q', 1000/(24.7*4.37)); % Glasberg and Moore's high-cf ratio
end

addpath ../../../matlab/
CF = CARFAC_Design(n_ears, fs, CF_CAR_params);
CF = CARFAC_Init(CF);

for ear=1:CF.n_ears
% This method
CAR_coeffs = CF.ears(ear).CAR_coeffs;
r1=CAR_coeffs.r1_coeffs;
a0=CAR_coeffs.a0_coeffs;
h=CAR_coeffs.h_coeffs;
g=CAR_coeffs.g0_coeffs;
c=CAR_coeffs.c0_coeffs;
zB = CF.ears(ear).CAR_state.zB_memory; % current delta-r from undamping
r = r1 + zB;
b(:, :, ear)=g.*[ones(CF.n_ch, 1) (h.*r.*c - 2*r.*a0) (r.^2.*(c.^2 + a0.^2))];
a(:, :, ear)=[ones(CF.n_ch, 1) -2*r.*a0 r.^2.*(c.^2 + a0.^2)];

% This method uses CARFAC_Rational_Functions to generate the IIR filter coefficients
% CARFAC_Rational_Functions is found in carfac/matlab/CARFAC_Transfer_Functions.m
% [b(:,:,ear), a(:,:,ear), g(:,ear)] = CARFAC_Rational_Functions(CF, ear);
end
123 changes: 123 additions & 0 deletions other/car/matlab/CAR_Test.m
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,123 @@
% Copyright 2012 The CARFAC Authors. All Rights Reserved.
% Author Richard F. Lyon
%
% This file is part of an implementation of Lyon's cochlear model:
% "Cascade of Asymmetric Resonators with Fast-Acting Compression"
%
% Licensed under the Apache License, Version 2.0 (the "License");
% you may not use this file except in compliance with the License.
% You may obtain a copy of the License at
%
% http://www.apache.org/licenses/LICENSE-2.0
%
% Unless required by applicable law or agreed to in writing, software
% distributed under the License is distributed on an "AS IS" BASIS,
% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
% See the License for the specific language governing permissions and
% limitations under the License.

function status = CAR_Test(do_plots)
% CARFAC_TEST returns status = 0 if all tests pass; nonzero if fail,
% and prints messages about tests and failures. Argument do_plots is
% optional, defaults to 1 (as when executing the file as a script).
% Run CARFAC_Test(0) to suppress plotting.

if nargin < 1, do_plots = 1; end % Produce plots by default.

% Run tests, and see if any fail (have nonzero status):
status = 0; % 0 for OK so far; 1 for test fail; 2 for error.
status = status | test_CAR_biquad(do_plots);
report_status(status, 'CAR_Test', 1)
return

function status = test_CAR_biquad(do_plots)
% Test the linear open loop biquadratic implementation of the CAR filters
status = 0; % start in the passing state
addpath ../../../matlab/
n_ears=1;
fs=22050;
[~, b, a]=CAR_Design(n_ears, fs);
b=b(:, :, 1); % only look at the first ear for now
a=a(:, :, 1);
M=size(b, 1);
N=fs; % take a one second response
% find the impulse response
x=zeros(N, 1);
x(1)=1;
y(:, 1)=filter(b(1, :), a(1, :), x);
for m=2:M % ripple through the cascade
y(:, m)=filter(b(m, :), a(m, :), y(:, m-1));
end

CF=CARFAC_Design(n_ears, fs);
CF.open_loop = 1; % For measuring impulse response.
CF.linear_car = 1; % For measuring impulse response.
CF = CARFAC_Init(CF);
[~, CF, bm_initial] = CARFAC_Run_Segment(CF, x);

if do_plots
Y=fft(y);

f=linspace(0, fs, N+1); f(end)=[];

figure(1); clf
semilogx(f, 20*log10(abs(Y))); grid on;
xlabel('f (Hz)'); ylabel('dB')
title('CAR filters')
% print -depsc /tmp/CAR.DFT.eps

Yref=fft(bm_initial);

figure(2); clf
semilogx(f,20*log10(abs(Yref))); grid on;
xlabel('f (Hz)'); ylabel('dB')
title('CARFAC reference')
% print -depsc /tmp/CARFAC.DFT.eps

figure(3); clf
semilogx(y); grid on;
xlabel('sample (n)'); ylabel('amp.')
title('CAR filters')
% print -depsc /tmp/CAR.t.eps

figure(4); clf
semilogx(bm_initial); grid on;
xlabel('sample (n)'); ylabel('amp.')
title('CARFAC filters')
% print -depsc /tmp/CARFAC.t.eps

figure(5); clf
semilogx(bm_initial-y); grid on;
xlabel('sample (n)'); ylabel('error')
title('Error between the CARFAC and biquad filters')
% print -depsc /tmp/CARFAC.CAR.error.t.eps
end

tol=1e-10;
if (rms(bm_initial - y) > tol)
status = 1; % indicate a test fail
fprintf(1, 'CAR biquad implementation is greater then %e from the cross coupled CAR implementation.\n', tol)
end

report_status(status, 'test_car')
return

function report_status(status, name, extra)
if nargin < 3, extra = 0; end
if extra
if status
disp(['FAIL ' name '; at least one test failed.'])
else
disp(['PASS ' name '; all tests passed.'])
end
else
if status
disp(['FAIL ' name])
if status > 1
disp('(status > 1 => error in test or expected results size)')
end
else
disp(['PASS ' name])
end
end
return