Adaptive Microphone Echo Cancellation for Uncorrelated Noise
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Solution Overview
Problem
Existing audio processing systems face challenges in accurately isolating target audio when surrounding noise includes uncorrelated noise, such as wind or touch noise, during echo cancellation in vehicle-mounted voice recognition devices.
Innovation Solution
An audio processing system comprising multiple microphones and adaptive filters, where a processor determines the presence of uncorrelated noise and adjusts filter coefficients, setting the intensity of noisy signals to zero to prevent their use in echo cancellation, thereby reducing processing load and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adaptive filters use surrounding audio as reference signal for echo cancellation, then echo cancellation performance is improved, but accuracy deteriorates when uncorrelated noise is present
Solution Approach 1:
The system dynamically adjusts the reference signal input to adaptive filters based on noise detection. When uncorrelated noise is detected in surrounding audio, the system switches off that microphone's input to the adaptive filter, making the reference signal dynamic rather than static. This resolves the contradiction by adapting the echo cancellation process to current noise conditions, maintaining reliability while preserving accuracy.
Solution Approach 2:
The system changes the parameter of reference signal selection based on noise characteristics. By detecting uncorrelated noise and switching the reference signal source or disabling noisy inputs, the system modifies operational parameters to avoid using contaminated reference signals. This allows effective echo cancellation when conditions are good while preventing accuracy degradation when noise is present.
2Reliability
If multiple microphones are used to capture surrounding audio for echo cancellation, then echo cancellation capability is improved, but processing complexity increases
Solution Approach 1:
The system segments the processing by dividing microphones into active and inactive groups based on noise detection. Instead of processing all microphone inputs through adaptive filters simultaneously, the system selectively activates only those microphones with clean signals. This segmentation reduces processing complexity while maintaining echo cancellation capability by focusing computational resources on useful inputs.
Solution Approach 2:
The system applies partial action by using only the necessary subset of microphones for echo cancellation at any given time. Rather than continuously processing all surrounding audio inputs, the system activates adaptive filters only with reference signals from microphones that are not experiencing uncorrelated noise, reducing overall processing complexity while maintaining sufficient echo cancellation capability.
3Measurement precision
If adaptive filters process all microphone signals, then noise removal capability is improved, but processing load increases
Solution Approach 1:
The system extracts and removes noisy microphone signals from the processing chain before they enter the adaptive filters. By detecting uncorrelated noise and switching off the input from affected microphones, the system takes out problematic signals that would otherwise consume processing resources without contributing useful information. This reduces processing load while maintaining noise removal capability for clean signals.
Data Source
AI summary
An audio processing system includes: a first microphone configured to output a first signal based on a first audio signal; one or more microphones each of which outputs a microphone signal based on an audio signal; one or more adaptive filters configured to respectively receive the microphone signals from the one or more microphones and output passing signals based on the microphone signals; and a processor configured to: determine whether the microphone signal includes uncorrelated noise; control one or more filter coefficients of the one or more adaptive filters; and subtract a subtraction signal based on the passing signals from the first signal. The one or more microphones include a second microphone that outputs a second signal. When determining that the second signal includes the uncorrelated noise, the processor is configured to set a level of the second signal input to the corresponding adaptive filter to zero.