Microphone Array Signal Processing for Interference Reduction
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Solution Overview
Problem
Existing noise interference reduction systems, such as generalized sidelobe cancellers, often attenuate desired signals and fail to accurately distinguish between echo sources and desired sounds, leading to unacceptable output distortions.
Innovation Solution
A system that processes sound signals from multiple microphones using a beamformer, echo canceller, and interference canceller, with adaptive filters and a blocking matrix to estimate and subtract unwanted signals, while a voice activity detector controls the activation of these components to minimize interference and preserve desired signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a generalized sidelobe canceller is used to reduce interference, then interference reduction is achieved, but desired signals are attenuated and output distortion increases
Solution Approach 1:
The system segments the interference reduction process into distinct functional blocks: a beamformer that processes microphone signals to create spatial filtering, an echo canceller that removes acoustic echoes, and an interference canceller that eliminates remaining interference. Each segment handles specific aspects of interference without affecting desired signals globally, thus reducing overall distortion while maintaining signal integrity.
Solution Approach 2:
The beamformer acts as an intermediary between the microphone array and the interference canceller. It processes the raw microphone signals first to create spatially-filtered intermediate signals, which then feed into subsequent cancellation stages. This intermediary processing allows the system to reduce interference through multiple progressive stages rather than a single aggressive filtering operation, thereby preserving desired signal components.
2Object-affected harmful factors
If echo cancellation is applied to remove reflected signals, then echo interference is reduced, but desired signals may be mistakenly attenuated
Solution Approach 1:
The echo canceller employs adaptive filtering with dynamically adjusted coefficients that continuously track and model the acoustic echo path. This dynamic adaptation allows the system to distinguish between actual echo components and desired speech signals, adjusting the cancellation strength in real-time based on the acoustic environment and signal characteristics, thereby avoiding attenuation of desired signals.
Solution Approach 2:
The system uses feedback mechanisms where the output of the echo canceller is monitored and used to adjust the filtering parameters. This feedback loop enables the system to learn from its performance and refine its echo cancellation strategy, ensuring that desired signals are preserved while echo interference is effectively removed through iterative optimization.
Data Source
AI summary
A system reduces noise or other external signals that may affect communication. A device converts sound from two or more microphones into an operational signal. Based on one or both signals, a beamformer generates an intermediate signal. Reflected or other undesired signals may be estimated or measured by an echo canceller. Interference may be measured or estimated by processing the echo-reduced signal or estimate by a blocking matrix. An interference canceller may reduce the interference that may modify or disrupt a signal based on the output of the blocking matrix and the intermediate signal.