Echo Cancellation in Full-Duplex Audio Systems
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Solution Overview
Problem
In full-duplex audio systems, lossy data compression interferes with echo cancellation, as the distortion introduced by codecs renders the accurate representation of microphone and loudspeaker signals necessary for echo cancellation inoperable, leading to suboptimal echo cancellation performance.
Innovation Solution
Placing the lossy audio codec farther away from the microphone and loudspeaker signals within the echo canceller's signal path and compensating for signal distortion by passing the loudspeaker signal through an identical codec, ensuring that the signal seen by the echo canceller matches the original signal, thus allowing for high-quality echo cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If lossy audio codec is applied to compress audio signals for wireless transmission, then bandwidth efficiency is improved, but signal distortion is introduced that interferes with echo cancellation
Solution Approach 1:
The system divides the audio processing into separate functional blocks: an audio codec for compression and an echo canceller for echo removal. By segmenting these functions, the patent allows the codec to compress signals for bandwidth efficiency while the echo canceller processes the decompressed signals to maintain echo cancellation performance, resolving the contradiction between compression and echo cancellation reliability
Solution Approach 2:
The patent introduces an intermediary approach by placing the echo canceller between the decompressor and the audio output, and another echo canceller between the microphone and the compressor. These intermediary echo cancellers compensate for the distortion introduced by the lossy codec, maintaining echo cancellation effectiveness while allowing bandwidth-efficient compression to occur
2Area of stationary object
If multiple microphones and loudspeakers are used to cover larger conference rooms, then coverage area is improved, but system complexity increases
Solution Approach 1:
The patent implements a standardized audio module containing microphone, loudspeaker, audio codec, and echo canceller that can be universally deployed in multiple instances throughout a conference room. Each module performs the same functions, and they can be combined to cover larger areas without proportionally increasing system complexity, as each module is self-contained and handles echo cancellation independently
Data Source
AI summary
A method, microphone module and a system for full-duplex audio system implementing full duplex audio, audio echo cancellation and audio codec. The audio signals from the microphones and to the loudspeakers are encoded to reduce the transmission bandwidth requirement during wired or wireless transmission and decoded when needed for further processing. Each microphone has transceivers to receive signals fed to loudspeakers within the microphone module. An audio echo canceller is installed within each microphone module to generate echo free audio signal for further signal processing. Problems due to the combination of lossy codec and echo cancellation are avoided.