Feedforward ANR Circuit With Speech-Band Talk-Through
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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 attenuation, and the creation of unwanted noise, particularly when attempting to allow talk-through functionality.
Innovation Solution
The ANR circuit reduces feedforward-based ANR by configuring filters to decrease the attenuation of human speech frequencies, either by ceasing ANR, amplifying speech, or adjusting filter coefficients to reduce noise attenuation within the human voice band, allowing for enhanced talk-through audio capabilities while maintaining noise reduction in adjacent frequency ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If feedforward-based ANR is provided at high degree, then environmental noise sounds are attenuated effectively, but power consumption increases and battery life decreases
Solution Approach 1:
The patent implements dynamic adjustment of feedforward-based ANR degree by detecting speech frequencies and automatically modifying filter coefficients. The system transitions between high-attenuation mode (for noise reduction) and low-attenuation mode (for speech passage), optimizing power consumption based on real-time acoustic conditions rather than maintaining a fixed high degree of ANR
2Object-affected harmful factors
If feedforward-based ANR is provided across wide frequency range, then more environmental noise sounds are attenuated, but human speech sounds are also attenuated causing unpleasant sounds
Solution Approach 1:
The patent applies local quality by creating frequency-specific treatment within the ANR system. Instead of uniform attenuation across all frequencies, the system identifies speech frequency ranges and applies selective notching or reduced attenuation in those specific bands while maintaining strong attenuation in non-speech frequency ranges. This localized differentiation preserves speech intelligibility while maintaining noise reduction effectiveness
3Object-affected harmful factors
If feedforward-based ANR is provided with high degree, then environmental noise sounds are reduced effectively, but unwanted noise sounds are created
Solution Approach 1:
The patent employs parameter changes by dynamically adjusting filter coefficients based on detected speech frequencies. When speech is detected, the system modifies the ANR parameters (reducing attenuation degree or creating notches) to prevent the generation of unwanted noise artifacts. This adaptive parameter adjustment ensures that the system operates in a stable regime that avoids creating harmful noise while maintaining effective environmental noise reduction
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution extends battery life, improves frequency range coverage, and reduces unwanted noise generation, enabling more effective and user-friendly talk-through functionality in ANR devices.
Implementation Method 1
a first acoustic driver coupled to the first ANR circuit to acoustically output feedforward anti-noise sounds
Implementation Method 2
a first feedforward microphone coupled to the first ANR circuit to detect environmental sounds
Data Source
AI summary
An ANR circuit, possibly of a personal ANR device, reduces the degree of feedforward-based ANR that it provides in response to receiving an indication of the operation of a manually-operable control. The reduction of degree of feedforward-based ANR may be effected by turning off or otherwise deactivating the provision of feedforward-based ANR, reducing a range of frequencies of environmental noise sounds attenuated by the feedforward-based ANR to provide less attenuation of sounds detected by a feedforward microphone that are in a range of frequencies deemed to be those of human speech, and/or creating a notch in the range of frequencies of environmental noise sounds attenuated by the feedforward-based ANR to provide less attenuation of sounds detected by the feedforward microphone that are in a range of frequencies deemed to be those of human speech.