Microphone Signal Attenuation Using Delay-Aligned Echo Correlation
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Solution Overview
Problem
Conventional methods for mitigating acoustic echo and audio feedback are ineffective when separate audio capture and output devices are used, as they fail to account for variable and unpredictable sound paths and delays, especially in wireless communication scenarios.
Innovation Solution
A method involving correlating and aligning audio signals from separate loudspeakers with microphone signals to determine a time delay, followed by attenuating the microphone signals based on the alignment and a weighted combination of the audio signals to reduce echo.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional echo cancellation methods are used, then echo mitigation is achieved in traditional setups, but they fail when separate audio capture and output devices are used with variable sound paths
Solution Approach 1:
The system dynamically determines time delays between audio signals and microphone signals for each specific device configuration. Instead of using fixed delay values, the system adapts to variable sound paths by calculating actual delays through correlation analysis, enabling reliable echo cancellation across different device combinations including separate audio capture and output devices
Solution Approach 2:
The system changes the parameter of time delay values based on the specific acoustic path between loudspeakers and microphones. By determining device-specific time delays through signal correlation and adjusting the echo cancellation parameters accordingly, the system achieves both reliability in echo mitigation and adaptability to various device configurations
2Loss of time
If audio signals are captured and processed in real-time, then low latency is achieved, but accurate time delay determination requires sophisticated correlation analysis
Solution Approach 1:
The system performs preliminary correlation analysis between audio signals and microphone signals to determine time delays before actual echo cancellation processing. By pre-determining the time delay parameters through cross-correlation of signal combinations, the system prepares the necessary parameters in advance, enabling low-latency real-time processing without requiring complex continuous analysis during the cancellation phase
3Object-generated harmful factors
If microphone signals are attenuated to reduce echo, then audio feedback is minimized, but excessive attenuation degrades voice capture quality
Solution Approach 1:
The system applies different attenuation levels to different microphone signals based on their individual correlation with the audio signal combination. Instead of uniform attenuation, each microphone signal is processed locally with a tailored attenuation factor determined by its specific contribution to echo, thereby minimizing audio feedback while preserving voice capture quality for microphones that are less prone to picking up loudspeaker output
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
Effectively reduces acoustic echo and audio feedback by individually attenuating microphone signals, accounting for variable sound paths and delays, improving audio quality in communications sessions.
Implementation Method 1
the means for correlating may be configured to perform cross-correlation of the first combination of the first and second audio signals with the one or more microphone signals to determine a maximum similarity value
Data Source
AI summary
Various example embodiments relate to microphone signal attenuation. An example method may comprise receiving one or more microphone signals from respective microphones for capturing first and second audio signals output by respective first and second loudspeakers and correlating a first combination of the first and second audio signals with the one or more microphone signals. The method may also comprise determining a time delay at which the first combination of the first and second audio signals is most similar to the one or more microphone signals. The method may also comprise aligning, or causing alignment of, the first and second audio signals to the one or more microphone signals based on the time delay, and attenuating, or causing attenuation of, the one or more microphone signals by an attenuation amount determined based at least in part on a second combination of the aligned first and second audio signals.