  We report a systematic improvement to calculate the conductivity which
associates to the anomaly of the propagation of surface acoustic waves at
$\nu={1/2}$ above a two-dimensional electron gas. We try to resolve the
discrepancy between theoretical and experimental values for the magnitude of
$\sigma_{xx}(q)$ by considering the contribution to the response functions from
the self-interaction among the Chern-Simons gauge fluctuations.
