Patent ID: 8155346
Filing Date: 2012-04-10
Classification: G01S

Abstract:
1. An audio source direction detecting device comprising: a generating unit configured to generate a first frequency spectrum that is a frequency spectrum in at least one frequency band of a first acoustic signal of a sound received by a first microphone and a second frequency spectrum that is a frequency spectrum in at least one frequency band of a second acoustic signal of the sound received by a second microphone spaced apart from the first microphone at a distance, the first acoustic signal including a first detected audio and a first noise, the second acoustic signal including a second detected audio and a second noise, and the first detected audio and the second detected audio being emitted from an audio source; a detected audio determining unit configured to (i) determine, from the first frequency spectrum, a first time-point portion that is a time-point portion in a frequency spectrum of the first detected audio, and (ii) determine, from the second frequency spectrum, a second time-point portion that is a time-point portion in a frequency spectrum of the second detected audio; and a detecting unit configured to: (i-a) calculate candidate arrival time differences each of which is a time difference between an arrival time of the sound to the first microphone and an arrival time of the sound to the second microphone, and (i-b) adjust, for each of the candidate arrival time differences, a time axis of the second frequency spectrum with respect to a time axis of the first frequency spectrum such that the arrival time difference becomes zero; (ii-a) determine, for each of the candidate arrival time differences, whether or not a percentage of an overlap time with respect to a unit of time is greater than a predetermined threshold, the unit of time being a unit of time for detecting an audio source direction that is a direction in which the sound is emitted, and the overlap time being a time period which is in the unit of time and during which the first time-point portion of the first frequency spectrum of the first acoustic signal is overlapped with the second time-point portion of the second frequency spectrum of the second acoustic signal having the adjusted time axis, and (ii-b) calculate a cross-correlation value between the first frequency spectrum and the second frequency spectrum, only when the percentage is determined to be greater than the predetermined threshold; and (iii-a) detect the audio source direction based on the arrival time difference at a time when the cross-correlation value is a local maximum, the distance between the first microphone and the second microphone, and an acoustic velocity, and (iii-b) output the detected audio source direction.