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1 % Copyright 2012, Google, Inc.
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2 % Author Richard F. Lyon
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3 %
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4 % This Matlab file is part of an implementation of Lyon's cochlear model:
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5 % "Cascade of Asymmetric Resonators with Fast-Acting Compression"
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6 % to supplement Lyon's upcoming book "Human and Machine Hearing"
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7 %
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8 % Licensed under the Apache License, Version 2.0 (the "License");
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9 % you may not use this file except in compliance with the License.
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10 % You may obtain a copy of the License at
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11 %
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12 % http://www.apache.org/licenses/LICENSE-2.0
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13 %
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14 % Unless required by applicable law or agreed to in writing, software
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15 % distributed under the License is distributed on an "AS IS" BASIS,
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16 % WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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17 % See the License for the specific language governing permissions and
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18 % limitations under the License.
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19
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20 function [naps, CF] = CARFAC_Run_Linear(CF, input_waves, extra_damping)
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21 % function [naps, CF] = CARFAC_Run_Linear(CF, input_waves, extra_damping)
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22 %
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23 % This function runs the CARFAC; that is, filters a 1 or more channel
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24 % sound input to make one or more neural activity patterns (naps);
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25 % however, unlike CARFAC_Run, it forces it to be linear, and gives a
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26 % linear (not detected) output.
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27
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28 % only saving one of these, really:
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29 saved_v_damp_max = CF.ears(1).CAR_coeffs.v_damp_max;
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30 for ear = 1:CF.n_ears
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31 CF.ears(ear).CAR_coeffs.v_damp_max = 0.00; % make it linear for now
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32 end
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33
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34 [n_samp, n_ears] = size(input_waves);
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35 n_ch = CF.n_ch;
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36
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37 if nargin < 3
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38 extra_damping = 0;
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39 end
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40
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41 if n_ears ~= CF.n_ears
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42 error('bad number of input_waves channels passed to CARFAC_Run')
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43 end
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44
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45 for ear = 1:CF.n_ears
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46 % Set the state of damping, and prevent interpolation from there:
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47 CF.ears(ear).CAR_state.zB_memory(:) = extra_damping; % interpolator state
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48 CF.ears(ear).CAR_state.dzB_memory(:) = 0; % interpolator slope
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49 CF.ears(ear).CAR_state.g_memory = CARFAC_Stage_g( ...
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50 CF.ears(ear).CAR_coeffs(ear), extra_damping);
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51 CF.ears(ear).CAR_state.dg_memory(:) = 0; % interpolator slope
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52 end
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53
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54 naps = zeros(n_samp, n_ch, n_ears);
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55
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56 for k = 1:n_samp
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57 % at each time step, possibly handle multiple channels
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58 for ear = 1:n_ears
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59 [filters_out, CF.ears(ear).CAR_state] = CARFAC_CAR_Step( ...
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60 input_waves(k, ear), CF.ears(ear).CAR_coeffs, CF.ears(ear).CAR_state);
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61 naps(k, :, ear) = filters_out; % linear
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62 end
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63 % skip IHC and AGC updates
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64 end
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65
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66 for ear = 1:CF.n_ears
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67 CF.ears(ear).CAR_coeffs.v_damp_max = saved_v_damp_max;
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68 end
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69
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