dicklyon@528: % Copyright 2012, Google, Inc.
dicklyon@528: % Author Richard F. Lyon
dicklyon@528: %
dicklyon@528: % This Matlab file is part of an implementation of Lyon's cochlear model:
dicklyon@528: % "Cascade of Asymmetric Resonators with Fast-Acting Compression"
dicklyon@528: % to supplement Lyon's upcoming book "Human and Machine Hearing"
dicklyon@528: %
dicklyon@528: % Licensed under the Apache License, Version 2.0 (the "License");
dicklyon@528: % you may not use this file except in compliance with the License.
dicklyon@528: % You may obtain a copy of the License at
dicklyon@528: %
dicklyon@528: %     http://www.apache.org/licenses/LICENSE-2.0
dicklyon@528: %
dicklyon@528: % Unless required by applicable law or agreed to in writing, software
dicklyon@528: % distributed under the License is distributed on an "AS IS" BASIS,
dicklyon@528: % WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
dicklyon@528: % See the License for the specific language governing permissions and
dicklyon@528: % limitations under the License.
dicklyon@528: 
dicklyon@565: function [naps, CF] = CARFAC_Run_Linear(CF, input_waves, relative_undamping)
dicklyon@565: % function [naps, CF] = CARFAC_Run_Linear(CF, input_waves, relative_undamping)
dicklyon@528: %
dicklyon@528: % This function runs the CARFAC; that is, filters a 1 or more channel
dicklyon@528: % sound input to make one or more neural activity patterns (naps);
dicklyon@528: % however, unlike CARFAC_Run, it forces it to be linear, and gives a
dicklyon@528: % linear (not detected) output.
dicklyon@528: 
dicklyon@561: % only saving one of these, really:
dicklyon@565: velocity_scale = CF.ears(1).CAR_coeffs.velocity_scale;
dicklyon@561: for ear = 1:CF.n_ears
dicklyon@565:   % make it effectively linear for now
dicklyon@565:   CF.ears(ear).CAR_coeffs.velocity_scale = 0;
dicklyon@561: end
dicklyon@528: 
dicklyon@534: [n_samp, n_ears] = size(input_waves);
dicklyon@528: n_ch = CF.n_ch;
dicklyon@528: 
dicklyon@553: if nargin < 3
dicklyon@565:   relative_undamping = 1;  % default to min-damping condition
dicklyon@553: end
dicklyon@553: 
dicklyon@534: if n_ears ~= CF.n_ears
dicklyon@528:   error('bad number of input_waves channels passed to CARFAC_Run')
dicklyon@528: end
dicklyon@528: 
dicklyon@534: for ear = 1:CF.n_ears
dicklyon@565:   coeffs = CF.ears(ear).CAR_coeffs;
dicklyon@530:   % Set the state of damping, and prevent interpolation from there:
dicklyon@565:   CF.ears(ear).CAR_state.zB_memory(:) = coeffs.zr_coeffs .* relative_undamping;  % interpolator state
dicklyon@561:   CF.ears(ear).CAR_state.dzB_memory(:) = 0;  % interpolator slope
dicklyon@565:   CF.ears(ear).CAR_state.g_memory = CARFAC_Stage_g(coeffs, relative_undamping);
dicklyon@561:   CF.ears(ear).CAR_state.dg_memory(:) = 0;  % interpolator slope
dicklyon@528: end
dicklyon@528: 
dicklyon@534: naps = zeros(n_samp, n_ch, n_ears);
dicklyon@528: 
dicklyon@528: for k = 1:n_samp
dicklyon@528:   % at each time step, possibly handle multiple channels
dicklyon@534:   for ear = 1:n_ears
dicklyon@561:     [filters_out, CF.ears(ear).CAR_state] = CARFAC_CAR_Step( ...
dicklyon@561:       input_waves(k, ear), CF.ears(ear).CAR_coeffs, CF.ears(ear).CAR_state);
dicklyon@534:     naps(k, :, ear) = filters_out;  % linear
dicklyon@528:   end
dicklyon@528:   % skip IHC and AGC updates
dicklyon@528: end
dicklyon@528: 
dicklyon@561: for ear = 1:CF.n_ears
dicklyon@565:   CF.ears(ear).CAR_coeffs.velocity_scale = velocity_scale;
dicklyon@561: end
dicklyon@528: