NOISE GATE, SOUND COLLECTION DEVICE, AND NOISE REMOVAL METHOD

摘要

A purpose of the invention is to provide a noise gate that can output an audio signal in which only a stationary noise is removed, without degrading an utterance voice of a speaking person. A sound collection device 1 includes an FFT processing unit 11, the noise gate 12, and an IFFT processing unit 13. The sound collection device 1 transforms a collected audio signal NE'T into a frequency spectrum NE'N by using the FFT processing unit 11. The noise gate 12 estimates a noise spectrum N'N of a stationary noise based on the frequency spectrum NE'N of the audio signal. The noise gate 12 decreases a signal level (a gain) of the audio signal in a case where a signal level ratio of the frequency spectrum NE'N of the audio signal to the noise spectrum N'N is less than a threshold value, and outputs the audio signal. The sound collection device 1 outputs an audio signal CO'T which is generated in such a manner that the IFFT processing unit 13 inversely transforms a frequency spectrum CO'N after removing the stationary noise N'N.