Adaptive Microphone Array Equalization for Side Interference
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Solution Overview
Problem
Adaptive microphone arrays degrade signals of interest due to speech leakage and artifacts caused by the adaptive filtering process, leading to interference reduction challenges in desired signal reception.
Innovation Solution
A method and apparatus that utilize a mirrored adaptive microphone array to model and minimize signal degradation by processing test signals recorded in anechoic environments, generating equalizer weights to correct for signal degradations in real-time adaptive arrays, thereby improving signal quality and reducing side interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If adaptive filtering is applied to reduce side interference, then interference reduction capability is improved, but signal quality of desired signals deteriorates due to speech leakage and artifacts
Solution Approach 1:
The patent divides the signal processing into two separate stages: (1) adaptive filtering stage that reduces side interference, and (2) equalization stage that corrects signal degradation. By segmenting the processing functions, the system can optimize each stage independently - the adaptive filter focuses on interference reduction while the equalizer restores signal quality, thus resolving the contradiction between interference reduction and signal quality preservation
Solution Approach 2:
The patent introduces an equalizer as an intermediary component between the adaptive filter and the final output. This equalizer acts as a mediator that compensates for the signal degradation caused by the adaptive filter. The equalizer uses test signals recorded in anechoic chambers to model and reverse the effects of speech leakage and artifacts, thereby maintaining signal quality while preserving the interference reduction benefits
2Object-affected harmful factors
If adaptive arrays are configured to reduce side interference, then interference rejection is improved, but signal degradation occurs in the main lobe due to speech leakage
Solution Approach 1:
The patent performs preliminary characterization of the array's signal degradation effects by recording test signals in an anechoic chamber environment before actual operation. These test signals capture the inherent speech leakage and artifact patterns of the specific array configuration. During operation, these pre-recorded test signals are used to train the equalizer, allowing the system to anticipate and correct for the expected signal degradation, thus preserving information while maintaining interference reduction
Solution Approach 2:
The patent implements a feedback mechanism where the equalizer continuously monitors the output of the adaptive array and adjusts its equalization parameters accordingly. The system uses the recorded test signals as reference feedback to model the degradation and applies corrective feedback to restore the original signal characteristics. This closed-loop feedback approach ensures that signal information is preserved while the adaptive filtering continues to reject side interference
Data Source
AI summary
Configuring an adaptive microphone array to gather signals from a main lobe of the array, and configuring the array to reduce side interference gathered from sources that are not situated within the main lobe. A memory stores test signals gathered by the array in an anechoic chamber, a free-field environment, or other echo, interference and noise-minimized acoustic environment. Signals gathered in real time are processed to provide a preliminary output and preliminary weights. The test signals are retrieved from memory. The preliminary weights are applied to the test signals to provide equalizer weights. The equalizer weights and the preliminary output generate an equalized output that minimizes degradations resulting from side interference reduction.