How to load or pick same variables from multiple files without overwriting the previous values

 I have three sudio files and each have the same variable.I want to store the values of the variables in same matrix without the previous value being overwritten.I will state the situation.

 filename = ' *audiointerface12.mat*';
 myVars = {'measuredSystem_L','measuredSystem_R'};
  S = load(filename,myVars{:});
  filename = 'audiointerface13.mat';
  myVars = {'measuredSystem_L','measuredSystem_R'};
  T = load(filename,myVars{:});
   filename = 'audiointerface15.mat';
  myVars = {'measuredSystem_L','measuredSystem_R'};
  U = load(filename,myVars{:});
I have written a code for this script but the previous values are getting overwritten.How can I keep such a script where all the values of the same variables are stored respective to the audiofile.
My code:
matfiles=dir('*audiointerface*.mat');
N=length(matfiles);
filenames=cell(N,1);

for i=1:N filenames{i}=matfiles.name; data=load(matfiles(i).name);

end