Active Noise Control Head Position Adaptation
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Solution Overview
Problem
Existing active noise control systems struggle to effectively cancel noise when a user's head displaces, requiring a large number of auxiliary filters and a complex configuration to maintain noise cancellation across a three-dimensional region.
Innovation Solution
An active noise control system with a head detection unit, switching control unit, and multiple auxiliary filters that detect and adapt to the user's head position, allowing for noise cancellation with a reduced number of filters by limiting noise cancel positions to the range of head and ear movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large number of auxiliary filters are provided to cover the entire three-dimensional region around the user's head, then noise cancellation effectiveness is improved across all head positions, but the device complexity and number of components increase excessively
Solution Approach 1:
The three-dimensional space around the user's head is segmented into multiple discrete noise cancel positions rather than attempting to cover the entire continuous space. This segmentation allows the system to use a manageable number of auxiliary filters (first, second, and third auxiliary filters) each optimized for specific spatial regions, thereby reducing overall system complexity while maintaining effective noise cancellation across different head positions.
Solution Approach 2:
Each auxiliary filter is designed with local quality optimization, where the first auxiliary filter is optimized for a first noise cancel position, the second for a second position, and the third for a third position. This localized optimization ensures that each filter performs best for its specific spatial region, achieving reliable noise cancellation without requiring excessive filters to cover the entire three-dimensional space.
2Adaptability or versatility
If multiple auxiliary filters are used to accommodate head displacement, then noise cancellation is maintained across different head positions, but the switching control logic and system complexity increase
Solution Approach 1:
The system implements dynamic switching between auxiliary filters based on the user's head position. The switching control unit continuously monitors head position and dynamically selects the appropriate auxiliary filter (first, second, or third) to ensure optimal noise cancellation. This dynamic adaptation allows the system to maintain effectiveness across different head positions without requiring all filters to operate simultaneously, thereby managing complexity through intelligent control rather than hardware redundancy.
3Manufacturing precision
If auxiliary filters are optimized for specific noise cancel positions, then noise cancellation precision at those positions is improved, but the system's ability to handle arbitrary head movements within three-dimensional space is reduced
Solution Approach 1:
The set of auxiliary filters is designed to be universally effective across the practical head movement range. By strategically selecting the number and positions of noise cancel positions (first, second, and third positions) and optimizing each auxiliary filter for these specific positions, the system achieves multi-functionality where the same set of filters can handle various head movements including turning and side bending within the predetermined angular ranges, without requiring excessive position-specific filters.
Data Source
Figure 1
Figure 2A1~2B2
Figure 3
AI summary
Provided is an "active noise control system (1)" capable of canceling noise regardless of displacement of a user's head. In a first system signal processing unit (111), an adaptive filter (1111 to 1114) generates a noise cancel sound, a first system selector (1117) selects an output of a first system auxiliary filter (1116) corresponding to a noise cancel position matching a detected position of a right ear of a user from a plurality of first system auxiliary filters (1116) corresponding to different noise cancel positions, and a first system subtractor (1115) subtracts the selected output from an output of a first microphone (13) and outputs the subtracted result as an error signal to a first system adaptive filter and a second system adaptive filter of a second system signal processing unit (112). The noise cancel positions corresponding to the plurality of first system auxiliary filters (1116) are arranged at predetermined intervals only in a space where the user seated on the seat can move the right ear due to turning and side bending of the head within a predetermined range in the up-down and front-back directions.