I devised the following program and used it in order to find all 8bit wav files in my computer.

clear
files=dir(fullfile(matlabroot,'work\Data hide\audio\*.wav'));
size=size(files);
for k=1:size(1)
name{k}=getfield(files,{k,1},'name');
end
i=1;
for k=1:size(1)
[data fs b]=wavread(name(k));
if(b==8)
eightbit{i}=name(k);
i=i+1;
end
end

notice that you should put all wav files in a folder and give its path to this program(line2) and then run it. you can see the name of 8bit files in matrix "eightbit". if it caused any errors first of all make sure that none of your files are compressed.
by means of this program I found 93 8bit wav files. now I'm going to download final program of last session and run it on all these files and see pairing phenomenon. but since this program doesn't matter whether the files are mono or stereo I wondered if the files should be mono or not...
I'm really eager to see pairing!!