  The paper explores in detail the use of dynamic adaptation gain/step size
(DAG) for improving the adaptation transient performance of variable step-size
LMS (VS-LMS) adaptation algorithms. A generic form for the implementation of
the DAG within the VS-LMS algorithms is provided. Criteria for the selection of
the coefficients of the DAG filter which is required to be a strictly positive
real transfer operator are given. The potential of the VS-LMS adaptation
algorithms using a DAG is then illustrated by experimental results obtained on
a relevant adaptive active noise attenuation system.
