Noise subtraction with parametric recursive gain curves

A well known technique for speech enhancement is spectral subtraction. This technique is attractive due to its simplicity and its low computational cost. We have proposed a simple modi cation of the lter coe cient calculation in form of a recursion of the previous lter coe cient. Because of this recursion the subtraction rule (gain curve) consists of two di erent paths, one for increasing signal-to-noiseratio and another for the decreasing ratio. In this paper we will introduce a parametric version of this recursive approach with two parameters controlling the crossover behaviour of the two paths. Although this recursive version is a very simple algorithm it is easily adjusted to produce no musical noise and additionally to get low speech distortion and/or low residual noise.