Hands-Free Echo Cancellation with External Gain Adjustment
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Solution Overview
Problem
Existing hands-free communication systems face challenges in reducing distortion and echo leakage due to non-linear distortion introduced by loudspeakers, which can lead to faulty echo cancellation and poor voice quality, as current solutions fail to account for variations in loudspeaker behavior and external gain changes.
Innovation Solution
A system and method that utilize a multiband compressor/limiter to adjust parameters and apply non-linear compression to the audio signal before playback, determining external gain values and using an average room coupling factor to mitigate distortion, ensuring the echo canceller operates within a linear range and effectively cancels echoes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external gain is increased to improve audio signal strength, then voice quality improves, but loudspeaker distortion increases causing echo cancellation failure
Solution Approach 1:
The system performs preliminary action by determining the external gain value before audio playback and using it to adjust echo canceller parameters in advance. The echo canceller is configured with distortion compensation based on the predicted loudspeaker behavior at the determined gain level, preventing distortion-induced echo cancellation failure before it occurs.
Solution Approach 2:
The system changes parameters by dynamically adjusting echo canceller parameters based on the determined external gain value. When external gain increases potentially causing distortion, the echo canceller parameters are modified to compensate for expected non-linear loudspeaker behavior, maintaining effective echo cancellation across varying gain levels.
2Reliability
If loudspeaker distortion is compensated to improve echo cancellation accuracy, then echo leakage reduces, but system complexity increases
Solution Approach 1:
The system uses feedback by determining the external gain value and using it to adjust echo canceller parameters. The echo canceller continuously adapts its parameters based on the current external gain setting, creating a closed-loop system that maintains accurate echo cancellation without requiring complex distortion modeling.
Solution Approach 2:
The system introduces an intermediary element - the determined external gain value - that mediates between the audio signal path and the echo canceller. This intermediary parameter allows the echo canceller to adapt to loudspeaker distortion without directly measuring or modeling the distortion itself, simplifying the overall system architecture.
3Object-generated harmful factors
If echo canceller parameters are dynamically adjusted to account for distortion, then echo leakage reduces, but processing time increases
Solution Approach 1:
The system performs preliminary action by determining the external gain value and pre-configuring the echo canceller parameters before audio playback. This advance configuration eliminates the need for real-time parameter adjustment during playback, reducing processing time while maintaining effective echo cancellation.
Data Source
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AI summary
A method of echo cancellation in hands-free communication is disclosed. The method includes: receiving, via a receive signal processor, a far-end audio signal; providing the far-end audio signal to: an acoustic echo canceller module as a reference signal, and at least one loudspeaker for playback; determining an external gain value associated with the far-end audio signal, the external gain applied to the far-end audio signal downstream of the receive signal processor and prior to playback from the at least one loudspeaker; adjusting at least one parameter of the acoustic echo canceller module based on the external gain value; receiving playback output of the far-end audio signal from the at least one loudspeaker as an input signal to a microphone; and processing the microphone input signal by the adjusted acoustic echo canceller module to produce an echo-cancelled signal.