Parallel Adaptive Filters for Faster Active Noise Control
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Solution Overview
Problem
Active noise control systems face inefficiencies in generating destructively interfering sound waves due to processing time required by bandpass filters and adaptive filters, which slows down the convergence of adaptive filters across different frequency ranges.
Innovation Solution
Implementing a system with multiple adaptive filters, each with a different filter length corresponding to specific frequency ranges, allowing them to converge independently and generate anti-noise signals that can be combined to quickly interfere with undesired sounds, with the option for one or more filters to contribute to the anti-noise signal before others have fully converged.
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 processing task into multiple parallel adaptive filters, each handling a specific frequency range. This segmentation allows simultaneous processing of different frequency components without sequential filtering delays, maintaining frequency precision while reducing overall processing time.
Solution Approach 2:
The patent transitions from a single sequential filter chain to a parallel multi-dimensional filter architecture. By processing multiple frequency ranges simultaneously across different filter paths rather than sequentially through one filter, the system eliminates the time penalty associated with sequential bandpass filtering while maintaining spectral precision.
2Speed
If multiple adaptive filters with different filter lengths are used, then convergence speed for different frequency ranges is optimized, but device complexity increases
Solution Approach 1:
Each adaptive filter is configured with a filter length specifically optimized for its assigned frequency range. Lower frequency ranges use longer filters for better convergence, while higher frequencies use shorter filters for faster response. This local optimization of filter parameters to match frequency characteristics maximizes convergence speed across the entire spectrum.
Solution Approach 2:
The system employs adaptive filter lengths that can be dynamically adjusted based on the characteristics of the input signal and convergence requirements. This dynamic configuration allows the system to optimize performance for different acoustic conditions while managing complexity through adaptive control mechanisms.
3Productivity
If parallel adaptive filters are implemented to increase efficiency, then noise cancellation speed improves, but system complexity increases
Solution Approach 1:
The patent combines multiple adaptive filter outputs into a single composite anti-noise signal that is sent to the loudspeaker. This merging of parallel processing paths achieves fast noise cancellation across all frequency ranges while consolidating the complex parallel operations into a unified output mechanism, managing system complexity through integration.
Solution Approach 2:
The parallel adaptive filter system serves multiple functions simultaneously: it processes different frequency ranges, adapts to varying acoustic conditions, and generates comprehensive noise cancellation. This multi-functionality justifies the increased complexity by delivering superior noise cancellation performance that a single filter cannot achieve.
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 enhances the efficiency of active noise control by allowing faster convergence of adaptive filters across varying frequency ranges, enabling quicker generation of effective anti-noise signals that can effectively destructively interfere with undesired sounds, thereby improving the overall performance of the active noise control system.
Implementation Method 1
generate sound waves that destructively interfere with a targeted undesired sound. The destructively interfering sound waves may be produced through a loudspeaker to combine with the targeted undesired sound
Data Source
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.