Acoustic Echo Cancellation with Loudspeaker Linearization
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Solution Overview
Problem
Existing two-way audio devices with nonlinear loudspeaker systems face challenges in acoustic echo cancellation, as residual echo suppression often removes both nonlinear distortion echoes and desired target signals, and the two-step echo cancellation process is susceptible to computation delays and reliability issues.
Innovation Solution
The audio system performs acoustic echo cancellation with loudspeaker linearization by generating a pre-distorted signal to keep the nonlinear loudspeaker system in a linear regime, capturing overall signals, filtering out the acoustic path response, and isolating the target signal using linear adaptive filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If residual echo suppression is used to attenuate nonlinear distortion echo, then echo cancellation is improved, but the desired target signal is also removed
Solution Approach 1:
The system performs loudspeaker linearization in advance by generating a pre-distorted signal that compensates for nonlinearities before the signal is processed by the loudspeaker. This preliminary action ensures the loudspeaker operates in its linear regime, preventing nonlinear distortion echo from occurring in the first place, thereby eliminating the need for residual echo suppression that would otherwise remove the target signal along with the echo
Solution Approach 2:
The system extracts and removes only the linear acoustic path response from the captured signal using linear adaptive filtering, while preserving the target signal. By separating the linear echo component through adaptive filtering based on the pre-distorted signal reference, the system eliminates echo without sacrificing the desired target signal
2Reliability
If a two-step echo cancellation process is used, then echo suppression is improved, but computation delays and reliability issues increase
Solution Approach 1:
The system merges loudspeaker linearization and echo cancellation into a single integrated process. By combining the pre-distortion generation with the linear adaptive filtering operation, the system eliminates the separate residual echo suppression step, thereby reducing computation delays while maintaining reliable echo cancellation performance
Solution Approach 2:
The system performs loudspeaker linearization in advance to prevent nonlinearities, which simplifies the subsequent echo cancellation to a single linear adaptive filtering step. This preliminary action reduces the complexity and computational delay of the overall process by eliminating the need for complex two-step processing
3Reliability
If residual echo suppression is used to prevent nonlinear distortion echo, then echo quality is improved, but the target signal clarity deteriorates
Solution Approach 1:
The system performs loudspeaker linearization in advance by generating a pre-distorted signal that ensures the loudspeaker operates in its linear regime. This prevents nonlinear distortion echo from occurring, thereby improving echo quality without requiring subsequent suppression that would compromise target signal clarity
Solution Approach 2:
The system extracts only the linear acoustic path response using linear adaptive filtering, separating it from the target signal. This selective extraction removes echo components while preserving the target signal, thereby improving echo quality without deteriorating target signal clarity
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 approach effectively isolates the target signal while preventing nonlinear distortion echoes from interfering, improving the accuracy and reliability of acoustic echo cancellation in nonlinear loudspeaker systems.
Implementation Method 1
Loudspeaker linearization involves modifying the input signal to form a pre-distorted signal that, when delivered by the nonlinear loudspeaker system, is in the linear regime
Implementation Method 2
capturing, via an acoustic sensor, an overall signal comprising an acoustic path response of the delivered audio content and a target signal
Implementation Method 3
The acoustic echo cancellation may comprise linear adaptive filtering based on the input signal as a reference to determining an expected acoustic path response
Data Source
AI summary
An audio controller comprising a nonlinear loudspeaker system; an acoustic sensor; and an audio controller is disclosed. The audio controller performs acoustic echo cancellation with loudspeaker linearization. In particular, the audio controller is configured to: generate a pre-distorted signal from an input signal that keeps the nonlinear loudspeaker system in a linear regime, deliver, via the loudspeaker system, audio content in the linear regime using the pre-distorted signal, capture, via the acoustic sensor, an overall signal comprising an acoustic path response of the delivered audio content and a target signal, filter out the acoustic path response of the delivered audio content from the overall signal yielding isolated target signal, and perform an action with the isolated target signal.