NOISE REDUCTION DEVICE, AUDIO INPUT DEVICE, RADIO COMMUNICATION DEVICE, AND NOISE REDUCTION METHOD

PROBLEM TO BE SOLVED: To provide a noise reduction device which can reduce noise components included in an audio signal in an appropriate manner under various circumstances.SOLUTION: A noise reduction device 1 related to the present invention comprises an audio interval determination unit 15 for determining an audio interval on the basis of audio collected by any one of microphones 11 and 12, an audio direction detector 16 for detecting arrival direction of audio on the basis of sound collection signals 21 and 22, and an adaptive filter 18 for conducting noise reduction processing using the sound collection signals 21 and 22 on the basis of audio interval information 24 output from the audio interval determination unit 15 and audio direction information 25 output from the audio direction detector 16. The audio direction detector 16 detects arrival direction of audio when the audio interval determination unit 15 determines that the audio collected is within the audio interval.