  We evaluate the ensemble averaged noise in a chaotic quantum dot subject to
DC bias and a periodic perturbation of frequency $\Omega$. The noise displays
cusps at bias $V_n=n\hbar\Omega/e$ that survive the average, even when the
period of the perturbation is far shorter than the dwell time in the dot. These
features are sensitive to the phase of the time-dependent scattering amplitudes
of electrons to pass through the system.
