The human ear cannot distinguish frequencies that are close together. If some frequencies are larger in magnitude than adjacent ones they can be removed to save space since they won't be heard. <masking.m>

One of the problems with this is that we have no good fall-off function or thresholds to use. We don't know what magnitude (relative to the loud frequency) frequencies can be cut and at what rate this decreases as we move away from the loud frequency.

We used x^2 as the fall-off function with arbitrary threshold and width.