How can I find mean crossing irregularity?

I have an sound file with 144000 data. I split this file into windows thanks to the buffer code. I want to find the mean crossing irregularity for each of these windows. if X denotes the random variable for the interval between two successive mean crossing indices.Mean crossing irregularity is defined as, the ratio of standard deviation of this variable to its' mean value. So I want to find this ratio for each of these windows. How can I do it? Thank you.

sound=structWheeze(2,1).SoundData;
piece = 400;

overlap = 200;
frames = buffer(sound, piece, overlap);


for k1 = 1:fix(size(frames,2)/10)
x = 1:length(sound);                                             
zci = @(v) find(v(:).*circshift(v(:), [-1 0]) <= 0);           
dy = zci(sound);                                                 
for k1 = 1:size(dy,1)-1
    b = [[1;1] [x(dy(k1)); x(dy(k1)+1)]]\[sound(dy(k1)); sound(dy(k1)+1)];   
    x0(k1) = -b(1)/b(2);                         

end
end