Audio signal processor, method, and program for suppressing noise components from input audio signals
First Claim
1. An audio signal processing device that suppresses noise components from input audio signals, the audio signal processing device comprising:
- a first directionality forming section that by performing delay-subtraction processing on an input audio signal forms a first directional signal imparted with a directionality characteristic having a null in a first specific direction;
a second directionality forming section that by performing delay-subtraction processing on the input audio signal forms a second directional signal imparted with a directionality characteristic having a null in a second specific direction different from the first specific direction;
a coherence computation section that obtains a coherence using the first and second directional signals;
a target-sound segment detection section that by comparing the coherence with a first determination threshold value determines whether the input audio signal is a segment of a target-sound arriving from a target direction, or a non-target-sound segment other than the target-sound segment;
a target-sound segment determination threshold value controller that based on the coherence detects an interfering-sound segment from among non-target-sound segments including both the interfering-sound segment and a background noise segment, that obtains an interfering-sound average coherence value representing an average coherence value in the interfering-sound segment, and that controls the first determination threshold value based on the interfering-sound average coherence value;
a gain controller that sets a voice switch gain according to a determination result of the target-sound segment detection section; and
a voice switch gain multiplication section that multiplies the input audio signal by the voice switch gain obtained by the gain controller.
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Abstract
The invention provides an audio signal processing device capable of improving sound quality by causing a voice switch to operate appropriately. Delay-subtraction processing is performed on an input signal to form a first and second directional signal with nulls in a first and second specific direction, respectively, and a coherence is obtained using the two directional signals. The coherence is then compared to a determination threshold value to determine whether the input audio signal is a target-sound segment arriving from a target-direction, or a non-target-sound segment other than the target-sound segment. A gain is set according to the determination result, and any non-target-sound is attenuated by multiplying the input signal by the gain. The determination threshold value is controlled based on an average value of coherence in interfering-sound segments.
8 Citations
10 Claims
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1. An audio signal processing device that suppresses noise components from input audio signals, the audio signal processing device comprising:
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a first directionality forming section that by performing delay-subtraction processing on an input audio signal forms a first directional signal imparted with a directionality characteristic having a null in a first specific direction; a second directionality forming section that by performing delay-subtraction processing on the input audio signal forms a second directional signal imparted with a directionality characteristic having a null in a second specific direction different from the first specific direction; a coherence computation section that obtains a coherence using the first and second directional signals; a target-sound segment detection section that by comparing the coherence with a first determination threshold value determines whether the input audio signal is a segment of a target-sound arriving from a target direction, or a non-target-sound segment other than the target-sound segment; a target-sound segment determination threshold value controller that based on the coherence detects an interfering-sound segment from among non-target-sound segments including both the interfering-sound segment and a background noise segment, that obtains an interfering-sound average coherence value representing an average coherence value in the interfering-sound segment, and that controls the first determination threshold value based on the interfering-sound average coherence value; a gain controller that sets a voice switch gain according to a determination result of the target-sound segment detection section; and a voice switch gain multiplication section that multiplies the input audio signal by the voice switch gain obtained by the gain controller. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An audio signal processing method that suppresses noise components from input audio signals, the audio signal processing method comprising:
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by a first directionality forming section, forming a first directional signal imparted with a directionality characteristic having a null in a first specific direction by performing delay-subtraction processing on an input audio signal; by a second directionality forming section, forming a second directional signal imparted with a directionality characteristic having a null in a second specific direction different from the first specific direction by performing delay-subtraction processing on the input audio signal; by a coherence computation section, calculating a coherence using the first and second directional signals; by a target-sound segment detection section, comparing the coherence with a first determination threshold value, and determining whether the input audio signal is a segment of a target-sound arriving from a target direction, or a non-target-sound segment other than the target-sound segment; by a target-sound segment determination threshold value controller, detecting based on the coherence an interfering-sound segment from among non-target-sound segments including both the interfering-sound segment and a background noise segment, obtaining an interfering-sound average coherence value representing an average coherence value in the interfering-sound segment, and controlling the first determination threshold value based on the interfering-sound average coherence value; by a gain controller, setting a voice switch gain according to a determination result of the target-sound segment detection section; and by a voice switch gain multiplication section, multiplying the input audio signal by the voice switch gain obtained by the gain controller.
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10. A non-transitory computer readable medium having computer program instructions for audio signal processing stored thereon, execution of the computer program instructions by a computer causing the computer to provide functions of:
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a first directionality forming section that by performing delay-subtraction processing on an input audio signal forms a first directional signal imparted with a directionality characteristic having a null in a first specific direction; a second directionality forming section that by performing delay-subtraction processing on the input audio signal forms a second directional signal imparted with a directionality characteristic having a null in a second specific direction different from the first specific direction; a coherence computation section that obtains a coherence using the first and second directional signals; a target-sound segment detection section that by comparing the coherence with a first determination threshold value determines whether the input audio signal is a segment of a target-sound arriving from a target direction, or a non-target-sound segment other than the target-sound segment; a target-sound segment determination threshold value controller that based on the coherence detects an interfering-sound segment from among non-target-sound segments including both the interfering-sound segment and a background noise segment, that obtains an interfering-sound average coherence value representing an average coherence value in the interfering-sound segment, and that controls the first determination threshold value based on the interfering-sound average coherence value; a gain controller that sets a voice switch gain according to a determination result of the target-sound segment detection section; and a voice switch gain multiplication section that multiplies the input audio signal by the voice switch gain obtained by the gain controller.
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Specification