Wideband and Sinusoidal Noise Reduction Based on Adaptive Filter with Variable Step Size

A noise reduction system based on an adaptive line enhancer (ALE) and a noise estimation filter (NEF) has been proposed to reduce both wideband and sinusoidal 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 to track the background noise without estimating a speech signal. Thus, a variable step size is introduced to the noise reduction system in this paper. The variable step size is decreased so as not to estimate speech in a speech section. 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.