1. An improved background noise estimator adapted for use with a noise suppression system wherein the background noise from a noisy pre-processed input signal is attenuated by spectral gain modification to produce a noise-suppressed post-processed output signal, said background noise estimator comprising: noise estimation means for generating and storing an estimate of the background noise power spectral density of the pre-processed signal; and noise detection means for periodically detecting the minima of the post-processed signal energy, and for controlling said noise estimation means in response thereto such that said background noise estimate is updated only during said minima.