Suppression of Two Noise Sources in the Same Direction by Instantaneous Spectral Subtraction

This study extends our noise suppression method using a microphone array to a case where a target and two noise sources are in the same direction. Four microphones are arranged to focus the target sound and their outputs are converted into a spatio-temporal sound pressure distribution image. The two-dimensional fast Fourier transform (2D FFT) spectral components of the target are localized as direct current (DC) components along the spatial axis. Meanwhile, the 2D-FFT components of noise signals are spread into the target spectrum. Based on the spread spectrum, the DC components of the noises are estimated in every temporal frame and subtracted from the target spectrum. Computational experiment indicates that the noise is suppressed by approximately 20 dB when the two noise sources are located farther than the target source.