Reversed Echo Cancellation for Co-located Conference Audio
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Solution Overview
Problem
Packet-based communication systems experience echo issues when multiple participants in the same acoustic space use multiple microphones and speakers, due to delays in audio signals propagated over the network, causing unwanted sound feedback during conference calls.
Innovation Solution
A method and system that compute delays in audio signals to identify and remove echo components by comparing microphone signals with audio signals intended for output, using a delay module and echo cancellation module to produce an echo-free output signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple microphones and speakers are used in the same acoustic space for conference calls, then audio coverage and participant inclusion are improved, but echo and audio feedback occur due to network signal delay
Solution Approach 1:
The system performs preliminary delay compensation by calculating the network transmission delay and advancing the playback timing of audio signals accordingly. This preliminary action prevents the audio signal from being played back after the direct sound has already been heard by participants, thereby eliminating echo before it can occur.
Solution Approach 2:
The system implements an active feedback mechanism where microphones continuously monitor the acoustic environment for echo signals. When echo is detected, the system generates compensatory signals to cancel the echo in real-time, creating a closed-loop control system that actively suppresses the harmful feedback.
2Object-generated harmful factors
If audio signals are transmitted over the network with delay compensation, then echo is reduced, but audio synchronization and timing accuracy deteriorate
Solution Approach 1:
The system dynamically adjusts the delay compensation parameter based on real-time network conditions and acoustic environment measurements. By continuously optimizing the delay value rather than using a fixed compensation amount, the system maintains both echo reduction effectiveness and audio timing accuracy under varying conditions.
3Reliability
If echo cancellation processing is applied in real-time, then audio clarity is improved, but computational complexity and processing load increase
Solution Approach 1:
The echo cancellation system is divided into separate functional modules: a delay compensation module that handles timing adjustments, a monitoring module that detects echo signals, and a cancellation module that generates suppressive signals. This segmentation allows each module to perform its specific function efficiently, reducing overall processing complexity while maintaining audio clarity.
Data Source
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AI summary
A method implemented during a communication event conducted between a user device and at least one further user device over a communications network, the method comprising: receiving an audio signal that is to be output from a speaker of said user device, said audio signal comprising at least one microphone signal transmitted from the at least one further user device; detecting that said audio signal comprises at least one audio component of a microphone signal transmitted from one or more of one of said at least one further user device that is co-located with said user device; and based on this detection, removing said at least one audio component from said audio signal to produce an output audio signal for output from said speaker.