Adaptive ANC Filter Tuning for Varying Ambient Noise

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Solution Overview

Problem

Conventional active noise cancellation (ANC) systems in personal listening devices do not effectively adapt to varying environments, leading to residual noise and audible artefacts, and performance is degraded by leakage variations between individuals and devices.

Innovation Solution

An adaptive noise cancellation system with a feedforward path using an adaptive filter and logic device to determine ambient noise conditions, adjusting parameters based on fullband and low-frequency power estimates to tune the filter and switch between different ANC modes, and incorporating adaptive gain control to manage leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional ANC systems use fixed filtering parameters, then the system structure remains simple, but noise cancellation performance degrades in varying environments

Engineering Contradiction:

Improvenoise cancellation performanceVSAvoidadaptation to varying environments

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent implements dynamic adaptation by continuously monitoring ambient noise characteristics through power estimation modules and automatically adjusting filter parameters based on detected noise conditions. The system transitions from static fixed parameters to dynamic adaptive parameters that respond to environmental changes, resolving the contradiction between maintaining simple structure and achieving reliable performance across varying environments.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes filter parameters based on detected ambient noise conditions. Power estimation modules analyze noise characteristics and trigger parameter adjustments when noise thresholds are exceeded, allowing the ANC system to adapt to different environmental noise levels and types, thereby improving reliability without requiring complex manual reconfiguration.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If the adaptive filter continuously adapts to all ambient noises, then adaptability improves, but residual noise and audible artefacts increase

Engineering Contradiction:

ImproveANC adaptionVSAvoidresidual noise and artefacts

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies different processing strategies to different frequency bands and noise conditions. Power estimation modules detect specific noise characteristics and trigger adaptive filtering only when and where appropriate, rather than continuously adapting across all frequencies. This localized adaptation reduces artefacts while maintaining effectiveness for problematic noise types.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The system incorporates feedback mechanisms where power estimation modules continuously monitor ambient noise and provide information to control logic that adjusts filter parameters accordingly. This feedback loop enables the system to adapt to noise conditions while monitoring for artefact generation, allowing it to optimize the balance between adaptability and noise cancellation quality.

Inventive Principle:

Principle #23Feedback

3Reliability

If ANC systems are tuned for optimal performance in specific environments, then noise cancellation is effective in those environments, but performance degrades in other environments

Engineering Contradiction:

Improvenoise cancellation effectivenessVSAvoidperformance across varying environments

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent creates a universal ANC system that can handle multiple noise environments through power estimation modules that detect ambient noise characteristics and automatically adjust filter parameters. Rather than requiring separate tuning for different environments, the system provides multi-functional adaptability by responding to various noise conditions with appropriate parameter adjustments, maintaining effectiveness across diverse environments.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Reliability

If the system monitors and adapts to ambient noise conditions, then noise cancellation performance improves, but device complexity increases

Engineering Contradiction:

Improvenoise cancellation performanceVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements partial monitoring by using power estimation modules that focus on detecting specific noise threshold conditions rather than continuously analyzing all ambient sound characteristics. This selective monitoring approach provides sufficient information for effective adaptation while minimizing the complexity overhead compared to comprehensive continuous analysis.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS20240185827A1Ambient detector for dual mode anc

Publication Date: 2024.06.06 GOOGLE LLC

AI summary

Active noise cancellation systems and methods include a feedforward path configured to receive a reference signal comprising ambient noise and adaptively generate an anti-noise signal to cancel the ambient noise. The adaptive filter is tuned in accordance with at least one parameter, which is set by a logic device configured to determine an ambient noise condition based the reference signal by estimating a fullband power of the reference signal, estimating a low-frequency power of the reference signal, comparing the fullband power and low-frequency power to one or more thresholds, and/or setting one or more ambient noise flags. The ambient noise condition may include a quiet background, a wideband noise condition, and/or a low-frequency dominant noise condition.