Echo Canceler Adaptive Filter Freeze for Non-Linear Audio Playback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Audio systems face interference from self-playback echo signals, which hinder the detection and processing of desired audio signals, such as user speech, due to acoustic reflections and coupling, and existing echo cancellers may diverge when encountering non-linear conditions in the playback section.
Innovation Solution
An audio system that includes a processor to detect non-linear conditions in the playback section and indicate them to an echo canceler, which then freezes the adaptation of adaptive filters to prevent divergence, ensuring effective echo reduction and voice capture by providing an echo reference signal and using multiple microphones and beam processing to enhance signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adaptive filters continuously adapt to reduce echo, then echo cancellation performance improves, but the system diverges under non-linear playback conditions
Solution Approach 1:
The system dynamically adjusts the adaptation state of the echo canceller based on detected playback conditions. When non-linear conditions are detected, the adaptive filter transitions from an adapting state to a frozen state, preventing divergence while maintaining current echo cancellation performance. This dynamic state adjustment resolves the contradiction by making the filter stable when needed and adaptive when safe.
Solution Approach 2:
The system implements a feedback mechanism where the playback section monitors its own output for non-linear conditions and provides this information back to the echo canceller. This feedback loop allows the echo canceller to anticipate potential instability and freeze adaptation proactively, preventing divergence before it occurs while maintaining optimal performance during linear operation.
2Stability of the object's composition
If the echo canceler freezes adaptation to prevent divergence, then stability is maintained, but echo reduction effectiveness decreases
Solution Approach 1:
The adaptive filter operates in a dynamic state machine that transitions between frozen and adapting states based on real-time condition assessment. During normal linear playback, the filter continuously adapts to maintain optimal echo cancellation. When non-linear conditions are detected, it freezes to prevent divergence, then resumes adaptation after conditions normalize, ensuring both stability and performance are maintained at appropriate times.
Solution Approach 2:
The system employs periodic monitoring of playback conditions with rhythmic transitions between adaptation and freezing states. Rather than permanently freezing the filter, the system periodically assesses conditions and resumes adaptation when safe, creating a cyclical pattern of adaptation-freeze-resume that maintains both stability and long-term effectiveness.
3Stability of the object's composition
If non-linear conditions are detected and adaptation is frozen, then divergence is prevented, but voice capture processing is modified
Solution Approach 1:
The system introduces an intermediary detection mechanism that monitors playback conditions and mediates between the adaptive filter and the voice capture processing. This intermediary layer detects non-linear conditions and selectively freezes adaptation only when necessary, rather than continuously interfering with voice capture. The intermediary ensures stability while minimizing impact on normal voice capture operations.
Solution Approach 2:
The system applies freezing locally and selectively rather than globally. When non-linear conditions are detected in specific frequency ranges or time periods, only the affected portions of the adaptive filter are frozen, while other portions continue to adapt and process voice signals normally. This localized approach maintains stability where needed while preserving voice capture quality elsewhere.
Data Source
AI summary
Audio systems and methods are provided that receive a playback signal and produce an acoustic signal based upon the playback signal, and include microphone signal(s) for capturing and processing user voice signals. An echo reference signal is based upon the playback signal, and an echo canceler reduces echo components from the microphone signal(s). Functionality of the echo canceler is modified, such as by freezing an adaptive filter, in response to a non-linear condition in the audio playback, or a likelihood of such a non-linear condition.