1. An apparatus comprising: a first circuit configured to (i) generate a first sample by filtering an input vector based on (a) a filter vector and (b) a stochastic vector, each of a plurality of components in said stochastic vector having a respective random value, and (ii) generate a second sample as a difference between a third sample and said first sample, said third sample being received from a network as an echo; and a second circuit configured to update a subset of a plurality of taps of said filtering where a corresponding one of said components of said stochastic vector has a first value of said random values.