Microphone Array Noise Suppression Using Segmented Pairs
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Solution Overview
Problem
Existing sound collecting apparatuses struggle to effectively suppress noise from directions other than the target sound direction, particularly in beamforming applications using microphone arrays, as they often fail to achieve optimal noise suppression due to limitations in microphone arrangement and signal processing.
Innovation Solution
A sound collecting apparatus with a signal processing unit that utilizes a generalized sidelobe canceller structure, comprising multiple microphone elements and adaptive filter units, is designed to suppress noise by generating reference signals with varied sensitivity characteristics, ensuring high sensitivity in the target sound direction and reducing noise from other directions through strategic microphone pair arrangement and beamforming techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional microphone array arrangements are used, then device complexity is reduced, but noise suppression capability deteriorates due to insufficient coverage of dead angles in reference signals
Solution Approach 1:
The microphone array is segmented into multiple pairs of microphone elements, where each pair generates a reference signal with specific dead angle characteristics. By dividing the array into segments with different orientations, the system achieves comprehensive noise suppression across multiple directions without requiring a single complex configuration
Solution Approach 2:
Different pairs of microphone elements are arranged with different orientations and spacing to create reference signals with complementary dead angle patterns. Each local pair is optimized for specific directions, and the combination of these locally optimized signals achieves global noise suppression performance
2Object-affected harmful factors
If the number of microphone elements is increased, then noise suppression capability is improved through better directional coverage, but device complexity and cost increase
Solution Approach 1:
Multiple reference signals from different microphone pairs are merged in the signal processing unit. By combining the outputs of multiple pairs with different dead angle patterns, the system achieves comprehensive noise suppression equivalent to or better than systems with many more individual elements, as the merged signals complement each other's directional coverage
Solution Approach 2:
Each pair of microphone elements serves multiple functions: capturing target sound signals while simultaneously generating reference signals for noise suppression. The same physical elements are used for both primary signal acquisition and noise reference generation, eliminating the need for separate dedicated noise reference microphones
3Object-affected harmful factors
If conventional beamforming is applied, then processing simplicity is maintained, but noise suppression effectiveness is insufficient due to inadequate reference signal diversity
Solution Approach 1:
The system performs preliminary generation of multiple reference signals with different dead angle characteristics before the main noise suppression processing. By pre-computing and storing these diverse reference signals from multiple microphone pairs, the adaptive filter can selectively combine them during operation, achieving superior noise suppression without real-time computational complexity
Data Source
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AI summary
A sound collecting apparatus capable of effectively suppressing sounds other than a target sound is provided. The sound collecting apparatus includes a plurality of microphones. A total number of effective microphone pairs in which a distance between two microphones is smaller than a distance D is larger than a total number of the plurality of microphones. The distance D is represented by D = c/2f, where the frequency of the target sound acquired from each of the plurality of microphones is f and sound velocity is c. When an angle formed by a straight line connecting two microphones configuring an effective microphone pair and a predetermined straight line is θ, the angles θ of all effective microphone pairs acquired from the plurality of microphones are different from each other.