Steerable Linear Differential Microphone Array Beamforming
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Solution Overview
Problem
Higher order differential microphone arrays (DMAs) face challenges in steering beamformers to effectively capture sound signals while minimizing noise sensitivity, particularly in applications like smart TVs where the sound source position varies, leading to suboptimal signal acquisition and noise reduction.
Innovation Solution
The design of steerable linear differential microphone arrays (LDMAs) involves defining ideal polynomial functions to describe target beampatterns, determining null constraints, and solving linear systems of equations to generate beamforming filters that can steer the beamformer away from the endfire direction, optimizing the directivity factor and white noise gain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If higher order differential microphone arrays are used to improve noise reduction, then the directivity factor is improved, but the beamformer cannot be steered away from the endfire direction, reducing adaptability to varying sound source positions
Solution Approach 1:
The patent applies dynamics by making the beamformer steerable through dynamic adjustment of weighting coefficients. The beamforming filter is designed to steer the beam away from the endfire direction by dynamically changing the weights applied to microphone signals based on the desired look direction, enabling adaptation to varying sound source positions while maintaining higher order differential array benefits
Solution Approach 2:
The patent uses parameter changes by modifying the weighting coefficients and beamforming filter parameters to achieve steering capability. The look direction is defined by parameters (azimuth and elevation angles) that control the beam orientation, and the system changes these parameters dynamically to track sound sources while preserving the noise reduction properties of higher order arrays
2Adaptability or versatility
If beamforming filters are designed to steer away from endfire direction, then adaptability to varying sound sources is improved, but the white noise gain increases, reducing noise reduction performance
Solution Approach 1:
The patent applies feedback by using the known array geometry and steering vector information to compute optimal weighting coefficients that balance steering capability with noise gain control. The system feedbacks the desired look direction information through the beamforming filter design to achieve the target beampattern while constraining the white noise gain
Solution Approach 2:
The patent uses parameter changes by optimizing the beamforming filter parameters (weighting coefficients) to achieve the desired steering angle while controlling the white noise gain. The system adjusts parameters such as the look direction angles and array geometry parameters to find the optimal balance between adaptability and noise performance
3Object-affected harmful factors
If higher order differential microphone arrays are used, then noise reduction is improved, but the complexity of generating steerable beamformers increases
Solution Approach 1:
The patent applies segmentation by dividing the complex beamforming problem into manageable components: array geometry definition, steering vector computation, weighting coefficient calculation, and filter design. This segmented approach allows systematic handling of higher order arrays while maintaining design tractability
Solution Approach 2:
The patent uses mechanics substitution by replacing complex manual design procedures with automated computational methods. The beamforming filters are generated through algorithmic processes that compute weighting coefficients based on array geometry and desired steering angles, eliminating the need for complex manual optimization while achieving optimal performance
Data Source
AI summary
An Nth order linear differential microphone array (LDMA) with a steerable beamformer may be constructed by specifying a target beampattern for the LDMA at a steering angle θ. An Nth order polynomial associated with the target beampattern may then be generated. A relationship between the nulls of the polynomial and the steering angle θ is determined and then a value of one of the nulls is determined based on N−1 assigned values for the other nulls and the determined relationship between the nulls of the polynomial and the steering angle θ. The steerable beamformer may be generated based on the determined null value and the N−1 assigned null values. The N−1 assigned null values may be associated with the N−1 nulls of the polynomial that are of less than Nth order and the determined null value may be associated with the null of the polynomial that is of Nth order.