Adaptive and Fixed Filter Noise Reduction Architecture
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Solution Overview
Problem
The combination of Feedforward (FF) and Feedback (FB) noise reduction methods in existing noise cancelling technologies often results in limited noise reduction effects, particularly for noises with varying characteristics.
Innovation Solution
A signal processing apparatus and method that generates a first noise reduction signal using an adaptive filter for noises with narrow frequency bandwidths and a second noise reduction signal using a fixed filter for noises with wide frequency bandwidths, combining both methods to effectively reduce a broader range of noise components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an adaptive filter is used for noise reduction, then noise reduction effectiveness is improved for varying characteristics, but device complexity increases
Solution Approach 1:
The patent divides the noise reduction system into multiple independent filter units (adaptive filters and fixed filters) that process different frequency bands separately. Each filter handles specific noise characteristics, allowing the system to achieve comprehensive noise reduction without requiring a single complex adaptive filter to handle all noise types.
Solution Approach 2:
The patent combines multiple filter outputs (adaptive filter output and fixed filter output) to generate the final noise reduction signal. This merging approach allows the system to leverage the strengths of both adaptive and fixed filters, achieving effective noise reduction for varying characteristics while maintaining manageable device complexity through modular architecture.
2Device complexity
If a fixed filter is used for noise reduction, then device complexity is reduced, but noise reduction effectiveness deteriorates for varying characteristics
Solution Approach 1:
The patent segments the frequency spectrum into multiple bands, with fixed filters handling specific frequency ranges where noise characteristics are relatively stable. This segmentation allows fixed filters to maintain simplicity while still providing effective noise reduction for their designated frequency ranges.
Solution Approach 2:
The patent merges the output of fixed filters with adaptive filters that handle varying noise characteristics. This combination allows the system to achieve comprehensive noise reduction effectiveness across all frequency bands while maintaining the simplicity of fixed filters for stable frequency ranges.
3Reliability
If multiple noise reduction methods are combined, then noise reduction effectiveness is improved across broader frequency bandwidth, but device complexity increases
Solution Approach 1:
The patent segments the noise reduction task into multiple parallel processing channels, each handling specific frequency bands with appropriate filter types. This segmentation allows the system to achieve broad frequency bandwidth coverage while keeping each processing channel relatively simple and manageable.
Solution Approach 2:
The patent creates a universal noise reduction system that can handle multiple noise types and frequency bands through a standardized multi-filter architecture. The system achieves multi-functionality by processing different noise characteristics through the same structural framework, reducing overall system complexity compared to separate specialized systems.
Data Source
AI summary
A signal processing apparatus includes a signal processor configured to: generate a first noise reduction signal using an adaptive filter based on a signal output from a first input apparatus, and cause the generated first noise reduction signal to be output by a first output apparatus; and generate a second noise reduction signal using a feedback filter based on a signal output from a second input apparatus, and cause the generated second noise reduction signal to be output by a second output apparatus. The feedback filter has a fixed feedback coefficient. The first input apparatus is located at a first noise-cancellation target location in an environment, and the second input apparatus is located at a second noise-cancellation target location in the environment, which may be different from the first noise-cancellation target location.