1. An active acoustic system comprising: a model reference having a selectably programmable response; an active model comprising in combination an acoustic path and an adaptive filter coupled in antiparallel feedback relation wherein the input of said adaptive filter receives the output of said acoustic path, and the output of said adaptive filter is supplied to the input of said acoustic path, such that the output of said acoustic path is fed back through said adaptive filter to the input of said acoustic path, and such that the combination of said acoustic path and said adaptive filter adaptively models said model reference such that the combined response of said acoustic path and said adaptive filter provides an active model response matching the response of said model reference.