MATLAB: How to apply pca to audio files (pitch features)

Question

Hello,

I applied pitch feature extraction to audio files. Now I want to apply PCA (for dimensionality reduction) to the pitch features. How can I do that? The problem is that I cannot save the features in csv or mat file. Also, the new audio feature replace the previous audio features thus giving me only feature vector i.e; comp_PCA1 gives me feature vector of 32600×1. But my files are 94 so the output should be 32600×94.

My code is given below:

clc
clear all
path_to_directory= dir ('**/*.wav'); % path to the directory 
for i = 1:length(path_to_directory)
    path= strcat(path_to_directory(i).folder, '\', path_to_directory(i).name);
    [signal, Fs]= audioread(path); % audio read here
     pitch = pwelch(signal);   % pitch feature extraction part
     [coeff,score] = pca(pitch); % pca for dimensionality reduction
     Comp_PCA1 = score(:,1);
% %      y (i,:)= coeff;   
end

Answer 1

path_to_directory= dir ('**/*.wav'); % path to the directory 
for i = 1:length(path_to_directory)
    filename = fullfile(path_to_directory(i).folder, path_to_directory(i).name);
    [signal, Fs]= audioread(path); % audio read here
     pitch = pwelch(signal);   % pitch feature extraction part
     [coeff,score] = pca(pitch); % pca for dimensionality reduction
     this_Comp = score(:,1);
     nR = size(this_Comp,1);
     if i == 1
         Comp_PCA1 = this_Comp;
     elseif nR <= size(Comp_PCA1,1)
         Comp_PCA1 = [Comp_PCA1(1:nR,:), this_Comp];
     else
         Comp_PCA1(:,i) = this_Comp(1:size(Comp_PCA1,1));
     end
end

If I got everything right then this should make Comp_PCA1 correspond in length to the shortest of the files.