Microphone Array Soundfield Decomposition for Video Conference Audio
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Solution Overview
Problem
Conventional video conference systems using distributed microphones suffer from aesthetic clutter, high installation and maintenance costs, and distorted audio due to coherent microphone signals with random phase delays, resulting in a comb filtering effect.
Innovation Solution
A microphone array is integrated into video conference endpoints to decompose the detected soundfield into sub-soundfields, which are then dereverberated and mixed to reduce reverberation and noise, extending the audio pickup range and filtering out unwanted interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If distributed microphones are placed on tables, walls, and ceilings to capture audio from participants, then audio capture coverage is improved, but device complexity and installation cost increase
Solution Approach 1:
Multiple microphones are merged into a single integrated microphone array at the video conference endpoint. The array combines multiple sensing elements into one unified device that can capture audio from multiple directions, eliminating the need for separately distributed microphones on tables, walls, and ceilings while maintaining comprehensive audio coverage.
Solution Approach 2:
The integrated microphone array performs multiple functions: it captures audio from various directions, determines soundfield characteristics, and identifies direct sound versus reverberation. This single multi-functional device replaces what would otherwise require multiple separate microphone placements throughout the room.
2Measurement precision
If distributed microphones are used to capture audio signals, then audio capture range is improved, but aesthetic appearance deteriorates due to room clutter
Solution Approach 1:
The solution consolidates multiple distributed microphone placements into a single integrated microphone array, eliminating the visual clutter of microphones scattered throughout the room while preserving the ability to capture audio from multiple directions and positions.
3Measurement precision
If microphone signals from distributed microphones are mixed together, then audio coverage is improved, but sound quality deteriorates due to comb filtering effect
Solution Approach 1:
The soundfield is segmented into distinct components: direct sound from participants and reverberation from room reflections. By separating these components through soundfield analysis and processing, the system can selectively combine only the direct sound signals, avoiding the comb filtering effect that occurs when all mixed signals including reverberation are combined.
Solution Approach 2:
The system extracts the direct sound component from the total soundfield by analyzing microphone array signals to identify and separate direct sound from reverberation. This extraction process removes the harmful reverberation signals before mixing, preventing the comb filtering effect while maintaining comprehensive audio coverage.
Data Source
AI summary
At a microphone array, a soundfield is detected to produce a set of microphone signals each from a corresponding microphone in the microphone array. The set of microphone signals represents the soundfield. The detected soundfield is decomposed into a set of sub-soundfield signals based on the set of microphone signals. Each sub-soundfield signal is processed, such that each sub-soundfield signal is separately dereverberated using other ones of the sub-soundfield signals to remove reverberation from the sub-soundfield signal, to produce a set of processed sub-soundfield signals. The set of processed sub-sound field signals are mixed into a mixed output signal.