dicklyon@467: % Copyright 2012, Google, Inc.
dicklyon@467: % Author Richard F. Lyon
dicklyon@467: %
dicklyon@467: % This Matlab file is part of an implementation of Lyon's cochlear model:
dicklyon@467: % "Cascade of Asymmetric Resonators with Fast-Acting Compression"
dicklyon@467: % to supplement Lyon's upcoming book "Human and Machine Hearing"
dicklyon@467: %
dicklyon@467: % Licensed under the Apache License, Version 2.0 (the "License");
dicklyon@467: % you may not use this file except in compliance with the License.
dicklyon@467: % You may obtain a copy of the License at
dicklyon@467: %
dicklyon@467: %     http://www.apache.org/licenses/LICENSE-2.0
dicklyon@467: %
dicklyon@467: % Unless required by applicable law or agreed to in writing, software
dicklyon@467: % distributed under the License is distributed on an "AS IS" BASIS,
dicklyon@467: % WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
dicklyon@467: % See the License for the specific language governing permissions and
dicklyon@467: % limitations under the License.
dicklyon@467: 
dicklyon@504: function [naps, CF] = CARFAC_Run_Linear(CF, input_waves, relative_undamping)
dicklyon@504: % function [naps, CF] = CARFAC_Run_Linear(CF, input_waves, relative_undamping)
dicklyon@467: %
dicklyon@467: % This function runs the CARFAC; that is, filters a 1 or more channel
dicklyon@467: % sound input to make one or more neural activity patterns (naps);
dicklyon@467: % however, unlike CARFAC_Run, it forces it to be linear, and gives a
dicklyon@467: % linear (not detected) output.
dicklyon@467: 
dicklyon@500: % only saving one of these, really:
dicklyon@504: velocity_scale = CF.ears(1).CAR_coeffs.velocity_scale;
dicklyon@500: for ear = 1:CF.n_ears
dicklyon@504:   % make it effectively linear for now
dicklyon@504:   CF.ears(ear).CAR_coeffs.velocity_scale = 0;
dicklyon@500: end
dicklyon@467: 
dicklyon@473: [n_samp, n_ears] = size(input_waves);
dicklyon@467: n_ch = CF.n_ch;
dicklyon@467: 
dicklyon@492: if nargin < 3
dicklyon@504:   relative_undamping = 1;  % default to min-damping condition
dicklyon@492: end
dicklyon@492: 
dicklyon@473: if n_ears ~= CF.n_ears
dicklyon@467:   error('bad number of input_waves channels passed to CARFAC_Run')
dicklyon@467: end
dicklyon@467: 
dicklyon@473: for ear = 1:CF.n_ears
dicklyon@504:   coeffs = CF.ears(ear).CAR_coeffs;
dicklyon@469:   % Set the state of damping, and prevent interpolation from there:
dicklyon@504:   CF.ears(ear).CAR_state.zB_memory(:) = coeffs.zr_coeffs .* relative_undamping;  % interpolator state
dicklyon@500:   CF.ears(ear).CAR_state.dzB_memory(:) = 0;  % interpolator slope
dicklyon@504:   CF.ears(ear).CAR_state.g_memory = CARFAC_Stage_g(coeffs, relative_undamping);
dicklyon@500:   CF.ears(ear).CAR_state.dg_memory(:) = 0;  % interpolator slope
dicklyon@467: end
dicklyon@467: 
dicklyon@473: naps = zeros(n_samp, n_ch, n_ears);
dicklyon@467: 
dicklyon@467: for k = 1:n_samp
dicklyon@467:   % at each time step, possibly handle multiple channels
dicklyon@473:   for ear = 1:n_ears
dicklyon@500:     [filters_out, CF.ears(ear).CAR_state] = CARFAC_CAR_Step( ...
dicklyon@500:       input_waves(k, ear), CF.ears(ear).CAR_coeffs, CF.ears(ear).CAR_state);
dicklyon@473:     naps(k, :, ear) = filters_out;  % linear
dicklyon@467:   end
dicklyon@467:   % skip IHC and AGC updates
dicklyon@467: end
dicklyon@467: 
dicklyon@500: for ear = 1:CF.n_ears
dicklyon@504:   CF.ears(ear).CAR_coeffs.velocity_scale = velocity_scale;
dicklyon@500: end
dicklyon@467: