Adaptive Microphone Array Compensation for Beamforming
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Solution Overview
Problem
Manufacturing tolerances and environmental factors cause variations in microphone sensitivities, leading to mismatches within microphone arrays, which degrade the performance of audio beam-forming and sound source localization techniques.
Innovation Solution
Adaptive calibration techniques are employed to equalize microphone signals by calculating and applying gains based on an energy reference, ensuring that all microphones produce similar responses, even across varying environmental conditions and frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple omni-directional microphones are used in a microphone array, then the capability for audio beam-forming and sound source localization is improved, but the sensitivity mismatches between microphones due to manufacturing tolerances and environmental factors degrade the performance
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the gain of each microphone signal based on its measured sensitivity. The system calculates a compensation factor for each microphone and applies it as a gain adjustment, transforming the raw microphone signals into compensated signals that have normalized sensitivities. This resolves the contradiction by allowing the system to maintain precise measurement across multiple microphones with inherently different sensitivities through mathematical parameter adjustment.
Solution Approach 2:
The patent implements feedback by measuring the actual sensitivity of each microphone and using this information to adjust the signal processing. The system continuously monitors the microphone array performance and adapts the compensation factors accordingly, creating a closed-loop system that maintains accuracy despite manufacturing variations and environmental changes.
2Ease of manufacture
If manufacturing tolerances are accepted in microphone production, then production cost and complexity are reduced, but the variations in microphone sensitivities greatly degrade beam-forming and sound source localization performance
Solution Approach 1:
The patent applies self-service by enabling the microphone array system to automatically compensate for its own sensitivity mismatches without requiring manual calibration or adjustment of the physical microphones. The system measures its own performance characteristics and self-adjusts the signal processing parameters to maintain optimal beam-forming performance, eliminating the need for complex manufacturing precision requirements.
Solution Approach 2:
The system changes the processing parameters (gain factors) based on measured sensitivity variations, allowing the same physical microphone array with tolerance variations to achieve reliable performance. This transforms the reliability issue into a manageable parameter adjustment problem rather than requiring manufacturing precision.
3Measurement precision
If microphone and pre-amplifier components are precisely matched, then beam-forming and sound source localization performance are optimized, but the complexity and cost of the system increase
Solution Approach 1:
The patent replaces the mechanical/physical matching approach (precise manufacturing tolerances and manual calibration) with an electronic/software-based solution. Instead of physically adjusting or selecting microphones to match precision specifications, the system uses digital signal processing to compensate for sensitivity variations, substituting mechanical precision requirements with computational correction.
Solution Approach 2:
The system achieves precise measurement matching by changing the gain parameter of each microphone signal in the digital domain. This parameter adjustment provides the same effect as physical matching but with significantly reduced system complexity, as it eliminates the need for precision manufacturing and manual calibration procedures.
Data Source
AI summary
An audio-based system may perform audio beamforming and/or sound source localization based on multiple input microphone signals. Each input microphone signal can be calibrated to a reference based on the energy of the microphone signal in comparison to an energy indicated by the reference. Specifically, respective gains may be applied to each input microphone signal, wherein each gain is calculated as a ratio of a energy reference to the energy of the input microphone signal.