Adaptive Feedback Cancellation Using Coherence Change Detection

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Solution Overview

Problem

Existing audio processing systems face challenges in effectively addressing the howling phenomenon due to rapid changes in the feedback path from a speaker to a microphone, as adaptive feedback cancellation modules struggle to track parameter estimation accurately, leading to incomplete echo cancellation.

Innovation Solution

An audio processing method and device utilizing a feedforward microphone and a feedback microphone to detect coherence change information, updating adaptive feedback canceller parameters based on this information, and performing echo cancellation to ensure real-time tracking of parameter estimation, thereby reducing the likelihood of howling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the AFC module uses adaptive parameter tracking to estimate feedback sound signals in real time, then echo cancellation can avoid the howling phenomenon under stable conditions, but when the feedback path changes drastically, the parameter estimation cannot track rapidly enough, resulting in incomplete echo cancellation and howling

Engineering Contradiction:

Improveecho cancellation effectivenessVSAvoidparameter tracking speed

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The patent applies dynamics by making the parameter update speed adaptive rather than fixed. The system dynamically adjusts the parameter update rate based on detected feedback path change conditions. When drastic changes are detected, the system increases update frequency; during stable periods, it uses normal update rates. This dynamic adaptation resolves the contradiction between tracking speed and cancellation effectiveness.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements parameter changes by modifying the parameter update rate based on feedback path stability. The system changes the speed at which adaptive parameters are updated according to the detected coherence between reference and error signals. This parameter adjustment mechanism allows the system to respond rapidly to feedback path changes while maintaining stability during normal operation.

Inventive Principle:

Principle #35Parameter changes

2Speed

If the AFC module updates parameters rapidly to track drastic feedback path changes, then parameter tracking speed improves, but system stability may deteriorate and false adjustments may occur

Engineering Contradiction:

Improveparameter tracking speedVSAvoidparameter estimation stability

Core Design Contradiction:

SpeedVSStability of the object's composition

Solution Approach 1:

The system uses dynamics to adjust parameter update rates based on real-time feedback path stability assessment. When instability is detected, the system increases update speed; when stable, it reduces update frequency. This dynamic control prevents false adjustments while maintaining tracking capability, resolving the contradiction between speed and stability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent applies feedback by continuously monitoring the coherence between reference and error signals to assess feedback path stability. This feedback mechanism informs the parameter update rate adjustment, ensuring that rapid updates only occur when genuinely needed. The feedback loop prevents false adjustments by validating changes against actual system conditions.

Inventive Principle:

Principle #23Feedback

3Device complexity

If the system uses a fixed parameter update rate in the AFC module, then system complexity is reduced, but the system cannot adapt to drastic changes in the feedback path, leading to howling

Engineering Contradiction:

Improveparameter update mechanism complexityVSAvoidfeedback path change adaptation

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent applies dynamics by transitioning from a fixed parameter update rate to a dynamic, condition-based update rate. The system adjusts the update frequency based on detected feedback path stability, adding adaptability without requiring complex algorithms. This dynamic approach resolves the contradiction between simplicity and adaptability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system implements parameter changes by modifying the parameter update rate based on feedback path conditions. Rather than using a fixed rate, the system changes the update rate parameter dynamically based on coherence detection. This parameter adaptation provides versatility while maintaining relatively simple implementation.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250349309A1Audio Processing to Reduce Feedback

Publication Date: 2025.11.13 ANKER INNOVATIONS TECH CO LTD

AI summary

Disclosed are an audio processing method and device, an audio apparatus, and a computer-readable storage medium for reducing a probability of a howling phenomenon of an audio apparatus. The method may be applied to an audio apparatus provided with a feedforward microphone, a feedback microphone, and/or an adaptive feedback canceller. Aspects described herein may comprise acquiring a first sound signal collected by the feedforward microphone and a second sound signal collected by the feedback microphone; detecting coherence change information between the first sound signal and the second sound signal, and updating canceller parameters of the adaptive feedback canceller according to the coherence change information; and/or performing echo cancellation on a pre-played audio signal of the audio apparatus according to the updated canceller parameters to obtain an actually played audio of the audio apparatus.