1. For use in a speech processing system having means for computing a plurality of temporal speech parameters including short-term parameters having time trajectories, a method for alleviating harmful effects of distortions of speech, the method comprising: performing a non-linear operation on a function of the short-term parameters of speech, the function being substantially linear for small values of the parameters and substantially logarithmic for large values of the parameters; and filtering data representing time trajectories of the short-term parameters of speech in a particular spectral domain to obtain a filtered spectrum and to minimize distortions due to convolutive noise and additive noise in speech.