Configurable ANR Filter Topology for Noise Reduction and Pass-Through Audio
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Solution Overview
Problem
Existing personal active noise reduction (ANR) devices face issues with high power consumption, limited frequency range, and the generation of unwanted noise, while also sometimes creating more noise than they reduce.
Innovation Solution
A personal ANR device with a signal processing topology that incorporates feedback-based, feedforward-based, and pass-through audio pathways, using a dynamically configurable ANR circuit with multiple microphones and acoustic drivers to generate and combine anti-noise sounds and audio signals, allowing for selective combinations and adjustments to optimize noise reduction and audio quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback-based ANR and feedforward-based ANR are both implemented with multiple microphones and acoustic drivers, then noise reduction effectiveness is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent segments the noise reduction system into distinct feedback and feedforward pathways, each with dedicated microphones and processing circuits. This segmentation allows independent optimization of each pathway while maintaining overall system effectiveness, managing complexity through modular organization of components and signal flows
Solution Approach 2:
The patent implements dynamically configurable signal processing topologies that can adaptively adjust the operation of different ANR pathways based on environmental conditions and power availability. This dynamic configuration enables the system to maintain high noise reduction effectiveness while managing device complexity and power consumption according to real-time requirements
2Reliability
If wide frequency range ANR is implemented, then noise reduction coverage is improved, but power consumption increases
Solution Approach 1:
The patent employs parameter changes by dynamically adjusting filter characteristics, gain settings, and processing intensity across different frequency bands. This allows the system to provide wide frequency range noise reduction when needed while reducing processing power consumption in frequency ranges where less noise reduction is required or when power is constrained
3Reliability
If aggressive ANR processing is applied, then noise reduction performance is improved, but unwanted noise generation increases
Solution Approach 1:
The patent uses feedback mechanisms where microphones monitor the acoustic output and feed this information back to the processing circuits. This feedback loop allows the system to detect and correct unwanted noise generation in real-time, adjusting the anti-noise signals to maintain effective noise reduction while minimizing the creation of unpleasant artificial sounds
Data Source
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AI summary
An ANR circuit, possibly of a personal ANR device, incorporates an signal processing topology to support the provision of feedback-based ANR, feedforward-based ANR and pass-through audio in which the topology incorporates a branch in which feedback anti-noise sounds are generated from feedback reference sounds received from a feedback microphone, a branch in which feedforward anti-noise sounds are generated from feedforward reference sounds, and a branch in which modified pass-through audio sounds are generated from pass-through audio sounds received from an audio source, wherein these three branches are combined to combine the generated sounds of each branch into a single output by which an acoustic driver, possibly of the personal ANR device, is driven. For each of these pathways, ANR settings for interconnections of each of the pathways, coefficients of each of the filters, gain settings of any VGA, along with still other ANR settings, are dynamically configurable wherein dynamic configuration is performed in synchronization with the transfer of one or more pieces of digital data along one or more of the pathways.