Noise reduction system using modified DFT pair

This paper presents a noise reduction system based on the modified DFT (MDFT) pair. The modified DFT decomposes noisy speech into sinusoidal signals which have the amplitude and phase spectra as the MDFT output. From each MDFT output, speech and noise spectra are extracted through level detectors. These detectors basically consist of the IIR filters with large time constants. By using the detected spectra, noise reduction is achieved in tile MDFT output and noise reduced speech is reconstructed by the modified IDFT (MIDFT) by only adding all MDFT outputs. The proposed system requires no preliminary estimation of noise spectrum since speech and noise spectra are extracted every sample time. The realization and effectiveness of the proposed system are confirmed through computer simulations