Adaptive Step-Size Beamformer for Coherent Noise Cancellation
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Solution Overview
Problem
Conventional beamforming systems, particularly fixed beamformers, are ineffective in isolating audio from a desired direction while effectively eliminating noise from a single, coherent source in a specific non-desired direction, as they struggle to dampen focused noise effectively.
Innovation Solution
A hybrid beamforming system combining a fixed beamformer and an adaptive beamformer with an adaptive step-size controller, which adjusts noise cancellation coefficients based on noise conditions, incorporates a microphone array to isolate desired audio and adaptively cancel noise from various directions, using noise reference signals to update filter weights and enhance noise removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed beamformer is used to isolate audio from a desired direction, then audio isolation from the desired direction is improved, but noise elimination from coherent directional sources deteriorates
Solution Approach 1:
The patent transitions from a static fixed beamformer to a dynamic adaptive beamformer that continuously adjusts its weights based on environmental noise conditions. The adaptive algorithm modifies the beamforming coefficients in real-time to track and cancel coherent directional noise sources, resolving the contradiction between maintaining audio isolation and eliminating adaptive noise cancellation capabilities
Solution Approach 2:
The patent changes the parameters of the beamformer by introducing adaptive weights that are continuously updated based on noise reference signals. This allows the system to modify its response characteristics dynamically, improving both audio isolation and coherent noise cancellation by adjusting the beamforming parameters according to current acoustic conditions
2Object-affected harmful factors
If an adaptive beamformer is used to cancel noise from different directions, then noise cancellation capability is improved, but system complexity increases
Solution Approach 1:
The patent segments the beamforming system into two distinct parts: a fixed beamformer component and an adaptive beamformer component. This segmentation allows each component to specialize in specific functions, with the adaptive portion focused solely on coherent noise cancellation, thereby managing overall system complexity through functional decomposition
Solution Approach 2:
The patent introduces noise reference signals as intermediary elements that carry information about environmental noise to the adaptive beamformer. These reference signals act as mediators that enable the adaptive algorithm to learn and cancel noise without requiring direct analysis of all microphone inputs, simplifying the adaptive processing requirements
3Object-affected harmful factors
If noise reference signals are used to update filter weights, then noise removal effectiveness is improved, but processing time increases
Solution Approach 1:
The patent performs preliminary action by using noise reference signals to pre-adapt the beamformer weights before actual noise cancellation is needed. The adaptive algorithm continuously updates weights in advance based on reference noise, so when coherent directional noise occurs, the system is already prepared with optimized weights, reducing real-time processing delays
Data Source
AI summary
A beamformer system that can isolate a desired portion of an audio signal resulting from a microphone array. A combination of beamformers is used to dampen undesired noise, whether diffuse or coherent. A fixed beamformer is used to dampen diffuse noise while an adaptive beamformer is used to cancel directional coherent noise. The adaptive beamformer isolates and weights audio from various directions. The weights may vary depending on the isolated desired audio signal, dynamically adjusting the step-size adjustments to the weights.