Steerable First-Order Differential Microphone Array
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Solution Overview
Problem
Existing differential microphone arrays (DMAs) lack the ability to steer their beamformers away from the endfire direction, limiting their flexibility in capturing sound sources at various angles, especially in applications like smart TVs and smartphones.
Innovation Solution
The approach involves decomposing the target beampattern into two sub-beampatterns, a cardioid and a dipole, and constructing two sub-beamformers to achieve these patterns. The first sub-beamformer is traditional, while the second is designed to filter squared observation signals to approximate the dipole pattern, allowing for steering of the main lobe.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional differential microphone array is used, then the beamformer can capture sound sources at the endfire direction, but it cannot steer the beamformer to other directions
Solution Approach 1:
The patent divides the beamforming process into two independent sub-beamformers: a first sub-beamformer for endfire direction capture and a second sub-beamformer for steerable directional capture. Each sub-beamformer processes specific components of the microphone array output, allowing independent optimization and steering control without redesigning the entire array structure.
Solution Approach 2:
The patent implements dynamic steering capability by allowing the second sub-beamformer to be steered to any direction within the range of [0, π] based on the desired sound source location. This dynamic adjustment is achieved through signal processing weights that can be modified in real-time, enabling the system to adapt to different spatial configurations without physical reconfiguration.
2Adaptability or versatility
If the beamformer is steered away from the endfire direction, then sound sources at various angles can be captured, but the traditional DMA structure cannot support this steering
Solution Approach 1:
The patent segments the directional response into two independent components: the first sub-beamformer handles the endfire directional response while the second sub-beamformer handles the steerable directional response. This segmentation allows each component to be optimized independently, with the second sub-beamformer providing flexible steering control for various angles without affecting the endfire capability.
Solution Approach 2:
The patent introduces an intermediary processing stage where the output of the microphone array is divided into two separate processing paths. The second sub-beamformer acts as an intermediary that can be steered to any direction within [0, π], serving as a mediator between the fixed endfire detection and the desired steerable directional capture, thereby enabling flexible operation without redesigning the entire system.
Data Source
AI summary
A first-order differential microphone array (FODMA) system with a steerable beamformer. The system includes a plurality (M) of microphones located on a substantially planar platform, the plurality of microphones comprising a first subset (M_1) of microphones and a second subset (M_2) of microphones, and a processing device, communicatively coupled to the plurality of microphones, configured to construct a first sub-beamformer based on the first sub-set (M_1) of microphones and a target beampattern at a steering angle θ, wherein the first sub-beamformer is characterized according to a first-order cosine (cardioid) first sub-beampattern, construct a second sub-beamformer based on the second sub-set (M_2) of the microphones and the target beampattern at the steering angle θ, wherein the second sub-beamformer is characterized according to a first-order sinusoidal (dipole) second sub-beampattern, and generate the steerable beamformer based on the first sub-beamformer and the second sub-beamformer.