Adaptive Beamformer for Nonlinear Echo Cancellation
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Solution Overview
Problem
Conventional audio devices face challenges in effectively canceling nonlinear echo signals due to the nonlinear nature of audio transducers, which traditional acoustic echo cancelers are unable to address, leading to reduced performance in echo suppression.
Innovation Solution
The implementation of a beamformer with an echo suppression control unit and echo cancellation unit that dynamically adapts speech blocking and echo suppression filters, along with a persistence interference detector to identify and manage stationary noise or echo sources, and a plurality of acoustic echo cancelers for rapid adaptation during startup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional linear AECs are used for echo cancellation, then linear echo signals can be reduced, but nonlinear echo signals from audio transducers cannot be addressed
Solution Approach 1:
The system dynamically adapts the beamformer between two operational modes (speech blocking and echo suppression) based on real-time detection of near-speech and echo conditions. This dynamic switching enables the system to handle both linear and nonlinear echo signals effectively, resolving the contradiction between reliable linear echo cancellation and adaptability to nonlinear echo.
Solution Approach 2:
The system changes the operational parameters of the beamformer by switching between different filter configurations (speech blocking filter vs. echo suppression filter). This parameter change allows the system to adapt its echo cancellation capability to match the actual acoustic conditions, enabling handling of both linear and nonlinear echo signals.
2Object-affected harmful factors
If a beamformer is used to reduce noise, then noise suppression is improved, but residual echo is not canceled
Solution Approach 1:
The beamformer is designed to perform multiple functions by dynamically adapting between speech blocking mode and echo suppression mode. When in echo suppression mode, the beamformer cancels residual echo in addition to noise, making the system universal in handling both noise and echo simultaneously, thus resolving the contradiction between noise suppression and residual echo cancellation.
Solution Approach 2:
The system uses dynamic mode switching to enable the beamformer to perform both noise suppression and echo cancellation as needed. The persistence interference detector triggers appropriate beamformer adaptation modes, allowing the single beamformer structure to universally address multiple harmful factors (noise and residual echo) without compromising either function.
3Reliability
If the echo suppression filter is dynamically adapted, then echo cancellation is improved, but speech blocking capability may be affected
Solution Approach 1:
The system dynamically switches between two distinct beamformer modes: speech blocking mode and echo suppression mode. This dynamic adaptation ensures that when echo suppression is active, speech blocking is temporarily suspended, and vice versa. The persistence interference detector monitors conditions and triggers appropriate mode switching, resolving the contradiction by making the system adaptive to current acoustic conditions rather than attempting to simultaneously optimize both conflicting functions.
Solution Approach 2:
The system periodically evaluates acoustic conditions through the persistence interference detector and switches between speech blocking and echo suppression modes accordingly. This periodic assessment and switching mechanism ensures that the beamformer adapts its function based on whether near-speech or echo is the dominant interference, resolving the contradiction between echo suppression and speech blocking capabilities.
Data Source
AI summary
An apparatus includes a beamformer, an echo suppression control unit, and a residual echo cancellation unit. The beamformer is configured to pass desired portions of audio signals and to suppress undesired portions of the audio signals. The beamformer includes a speech blocking filter to prevent suppression of near-end desired talker speech in the audio signals and an echo suppression filter to suppress echo in the audio signals. An echo suppression control unit is coupled to the beamformer and receives signals and determines whether to dynamically adapt the speech blocking filter or to dynamically adapt the echo suppression filter. The speech blocking filter remains unchanged during dynamic adaptation of the echo suppression filter, and the echo suppression filter remains unchanged during dynamic adaptation of the speech blocking filter. The residual echo cancellation unit is coupled to the beamformer and receives output audio signals from the beamformer and further suppresses residual echo.