Direction-Dependent Forward Cancellation for Hybrid ANC
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hybrid active noise cancellation systems face challenges in achieving optimal performance due to the need for precise matching of the internal filter response to the noise propagation path, which is often energy-intensive and complex to implement effectively.
Innovation Solution
The system employs a direction-dependent single-source forward cancellation method using a primary and secondary external microphone to estimate the predominant direction of sound arrival, adjusting a forward filter to match the noise propagation path, thereby improving noise cancellation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hybrid cancellation systems use both internal and external microphones to improve performance, then noise cancellation performance is improved, but system complexity and energy consumption increase
Solution Approach 1:
The patent extracts the direction estimation function from the full hybrid system and implements it separately using only external microphones. The direction finder module processes signals from external microphones to determine noise direction, which then guides the forward filter without requiring internal microphone feedback, thus reducing system complexity while maintaining performance
Solution Approach 2:
The system segments the noise cancellation process into independent functional modules: direction estimation using external microphones, forward filtering based on direction, and speaker output. This modular approach allows each component to be optimized independently and reduces overall system complexity compared to a monolithic hybrid system
2Reliability
If complex filter adaptation strategies are used to match internal filter response to noise propagation path, then noise cancellation performance is improved, but energy consumption increases
Solution Approach 1:
The forward filter dynamically adapts its characteristics based on real-time direction estimates from the direction finder. Instead of using complex continuous adaptation strategies, the system updates filter parameters discretely according to detected noise direction, reducing computational energy while maintaining effective noise cancellation across varying acoustic conditions
Solution Approach 2:
The system changes filter parameters based on direction estimates rather than continuously adapting all filter characteristics. By adjusting only the necessary filter parameters according to the predominant noise direction, the system achieves effective noise cancellation with lower energy consumption compared to comprehensive filter adaptation
3Use of energy by moving object
If forward cancellation systems use simple filter responses, then energy efficiency is improved, but noise cancellation performance deteriorates due to poor matching
Solution Approach 1:
The direction finder continuously estimates noise direction in advance to guide the forward filter configuration. By preparing direction information before noise cancellation is needed, the system can pre-configure appropriate filter responses, achieving both energy efficiency and good performance without requiring complex real-time adaptation
Data Source
AI summary
Active noise cancellation systems, components, and methods are provided with single-source forward cancellation using a direction-dependent filter response. One illustrative active sound cancelling device includes: a primary external microphone that produces a primary receive signal; a secondary external microphone that produces a secondary receive signal, the primary and secondary receive signals representing ambient audio that potentially includes sound having a predominate direction of arrival; a speaker that converts an output signal into internal audio to at least partly cancel said sound, the output signal including a forward cancellation signal; a forward filter that operates solely on the primary receive signal to produce the forward cancellation signal; and a direction finder that operates on the primary and secondary receive signals to derive an estimate of said predominate direction of arrival, the direction finder adjusting the forward filter to implement a filter response corresponding to said estimate.