% highpass   // High-pass filter music.
lambda = 0.97;  % Higher lambda = more smoothing.
ylow_prev = 0;
ylow = zeros(length(y),1);
for index = 1:length(y)
  ylow_next = ylow_prev * lambda +y(index);
  ylow(index) = ylow_next;
  ylow_prev = ylow_next;
end
yhigh = y - ylow;
yhigh = yhigh * sum(y.^2)/sum(yhigh.^2);
y = yhigh;
louder
louder
louder
