### Error Weighting and Frequency Warping

Audio filter designs typically benefit from an *error weighting
function* that weights frequencies according
to their audibility. An oversimplified but useful weighting function
is simply , in which low frequencies are deemed generally
more important than high frequencies. Audio filter designs also
typically improve when using a *frequency warping*, such as
described in [88,78] (and similar to that
in §I.3.2). In principle, the effect of a frequency-warping can
be achieved using a weighting function, but in practice, the numerical
performance of a frequency warping is often much better.

**Next Section:**

Stability of Equation Error Designs

**Previous Section:**

Equation Error Formulation