Speech enhancement based on adaptive filter with variable step size for wideband and periodic noise

A speech enhancement system based on an adaptive line enhancer (ALE) and a noise estimation filter (NEF) has been proposed to reduce both wideband and periodic noise in noisy speech. However, it is inevitable to use a small step size which enables us to update tap coefficients of the NEF without estimating a speech signal. When a fixed step size is used, it is difficult for the speech enhancement system to reduce background noise while maintaining the high quality of enhanced speech. Thus, a variable step size is introduced to the NEF in this paper. In a speech section, the variable step size is decreased so as not to estimate speech. On the other hand, the variable step size is increased to track background noise in a non-speech section. Additionally, the variable step size is increased when the tap coefficients do not converge adequately.