Parallel Adaptive Filters for Active Noise Control
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Solution Overview
Problem
Existing active noise control systems are inefficient due to the processing time required by bandpass filters and adaptive filters, which hampers the generation of destructively interfering sound waves.
Innovation Solution
A system utilizing multiple adaptive filters with varying filter lengths, each configured to receive a common input signal, allowing them to converge quickly based on the frequency range and generate output signals that can be independently adjusted using error signals to produce anti-noise sound waves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If bandpass filters and adaptive filters are used to process undesired sound, then frequency range filtering is achieved, but processing time increases and efficiency decreases
Solution Approach 1:
The system divides the frequency spectrum into multiple sub-bands and processes each sub-band independently using separate adaptive filters. This segmentation allows parallel processing of different frequency components, reducing the overall processing time while maintaining frequency-specific filtering accuracy.
Solution Approach 2:
The patent transitions from sequential single-channel processing to parallel multi-channel processing by implementing multiple adaptive filters operating simultaneously on different frequency sub-bands. This dimensional change from time-sequential to space-parallel architecture reduces processing time while preserving frequency discrimination capability.
2Speed
If multiple adaptive filters with different filter lengths are used, then convergence speed for different frequency ranges is improved, but device complexity increases
Solution Approach 1:
Each adaptive filter is configured with a filter length optimized for its specific frequency sub-band. Lower frequency sub-bands use longer filters for better convergence, while higher frequency sub-bands use shorter filters for faster response. This local optimization of filter parameters to match frequency-specific requirements improves overall convergence speed without requiring uniform complexity across all filters.
Solution Approach 2:
The system varies the filter length parameter across different adaptive filters based on their assigned frequency ranges. By changing this key parameter to match the characteristics of each frequency sub-band, the system achieves optimal convergence performance for each band while managing overall system complexity through parameter differentiation rather than structural complexity.
3Productivity
If parallel adaptive filter configuration is implemented, then processing efficiency is improved, but system complexity increases
Solution Approach 1:
The parallel adaptive filter system segments the audio processing task into multiple independent frequency sub-band channels. Each channel processes a specific frequency range independently, enabling parallel execution that improves processing efficiency. The segmentation approach manages complexity by creating modular, independent processing units rather than a monolithic complex system.
Solution Approach 2:
Multiple adaptive filters with different configurations serve the universal function of noise cancellation across different frequency ranges. Each filter is specialized for its frequency band but all perform the same fundamental noise cancellation task, allowing the system to handle diverse frequency content with a unified parallel architecture that improves efficiency without proportionally increasing complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables faster convergence of adaptive filters, allowing for more efficient generation of anti-noise signals that effectively interfere with undesired sounds, improving the overall efficiency of active noise control.
Implementation Method 1
generate sound waves that destructively interfere with a targeted undesired sound
Data Source
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AI summary
An active noise control system includes a plurality of adaptive filters. The plurality of adaptive filters each receives an input signal representative of an undesired sound. The adaptive filters may each generate an output signal based on the input signal. The output signals are used to generate an anti-noise signal configured to drive a speaker to produce sound waves to destructively interfere with the undesired sound.