  We analyze the spectrum of the electric-current autocorrelation function
(noise power) in the Anderson impurity model biased by a finite transport
voltage. Special emphasis is placed on the interplay of non-equilibrium effects
and electron-electron interactions. Analytic results are presented for a
perturbation expansion in the interaction strength $U$. Compared to the
non-interacting setup we find a suppression of noise for finite frequencies in
equilibrium and an amplification in non-equilibrium. Furthermore, we use a
diagrammatic resummation scheme to obtain non-perturbative results in the
regime of intermediate $U$. At finite voltage, the noise spectrum shows sharp
peaks at positions related to the Kondo temperature instead of the voltage.
