ANR Circuit Downsampling for Power and Frequency Trade-offs
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Solution Overview
Problem
Existing personal active noise reduction (ANR) devices face issues with high power consumption, limited frequency ranges for noise cancellation, and the creation of unwanted noise, which affect their effectiveness and user experience.
Innovation Solution
The proposed solution involves an ANR circuit that uses feedback and feedforward reference data, along with pass-through audio data, to derive side-chain data for processing, which is then employed in an analysis to dynamically configure filters and provide adaptive noise reduction, including high-frequency phase compensation to enhance the range of noise cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high sampling rates are used in ANR processing, then noise reduction effectiveness is improved, but power consumption increases
Solution Approach 1:
The patent divides the digital data processing into two paths: a full-resolution path for ANR filtering and a downsampled path for analysis. The downsampling block (155) creates a lower-resolution copy of the reference data specifically for analysis purposes, allowing the main ANR processing to operate at reduced power consumption while maintaining effectiveness through the filtered output (125).
Solution Approach 2:
The patent introduces side-chain data (150) as an intermediary element that carries downsampled reference information from the ANR circuit to the processing device. This intermediary allows the processing device to perform analysis without requiring the full high-resolution data stream, thereby reducing the power burden on the ANR circuit while maintaining analysis accuracy.
2Measurement precision
If full-resolution reference data is transmitted to processing device, then analysis accuracy is improved, but data transmission load increases
Solution Approach 1:
The patent extracts only the essential information needed for analysis by downsampling the reference data (145) to create side-chain data (150). This extracted downsampled version contains sufficient information for the processing device to perform its analysis function without requiring the complete high-resolution data stream, thereby reducing transmission load while preserving analysis capability.
3Adaptability or versatility
If ANR is applied across wide frequency range, then noise cancellation coverage is improved, but stability decreases due to unwanted noise creation
Solution Approach 1:
The patent employs feedback-based ANR using feedback reference data (115) from the feedback microphone (110). The processing device analyzes this feedback data and adjusts filter coefficients (135) to maintain system stability. The feedback mechanism allows the system to adapt to wide frequency ranges while preventing unwanted noise creation by continuously monitoring and adjusting the ANR output based on actual performance.
Solution Approach 2:
The patent implements dynamic filter configuration where the processing device continuously analyzes reference sounds and adjusts ANR parameters in real-time. The filter coefficients (135) are dynamically updated based on the analyzed side-chain data, allowing the system to adapt to varying frequency conditions and maintain stability across wide frequency ranges rather than using fixed parameters.
Data Source
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AI summary
Method of supporting ANR analysis performed by a processing device coupled to an ANR circuit performing at least one of feedback-based and feedforward-based ANR in at least one earpiece of a personal ANR device, comprising: downsampling digital data representing reference sounds detected by at least one of a feedback microphone disposed within the at least one earpiece and a feedforward microphone disposed on a portion of the personal ANR device to derive a downsampled form of the digital data; operating an interface of the ANR circuit that couples the ANR circuit to a bus to which the processing device is also coupled to transmit said downsampled form to the processing device as side-chain data; operating the processing device to employ the side-chain data as an input to the ANR analysis, routing said downsampled form through a filter to provide weighting to frequencies of reference sounds represented by said downsampled form prior to operating said interface to transmit said downsampled form as the side-chain data to the processing device.