Signal Characteristic Determinator for DOA Estimation
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Solution Overview
Problem
Current methods for estimating sound field characteristics using higher-order spherical harmonic coefficients (SHCs) face high computational complexity and lack clarity in physical meaning, particularly in directional audio coding and sound field reproduction, where DOA estimation and diffuseness parameters are concerned.
Innovation Solution
The introduction of a signal characteristic determinator that uses weighted spatial averaging of higher-order SHCs of sound pressure and particle velocity to compute a generalized intensity vector and energy density, incorporating spherical-harmonic-order dependent weights for radial and direction-dependent spatial averaging, allowing for reduced computational complexity and improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If spherical harmonic domain versions of MUSIC and ESPRIT are used for DOA estimation, then measurement precision is improved, but device complexity increases due to eigendecomposition requirements
Solution Approach 1:
The patent extracts only the essential components needed for DOA estimation by using a simplified intensity vector calculation that bypasses the full eigendecomposition process. Instead of computing all eigenvalues and eigenvectors of the covariance matrix, the method directly calculates the intensity vector from the spherical harmonic coefficients, retaining the necessary directional information while eliminating computationally expensive operations.
Solution Approach 2:
The patent inverts the conventional approach by not starting with eigendecomposition and then extracting directional information, but rather directly computing the intensity vector from the spherical harmonic coefficients in a single step. This reverse engineering of the calculation process achieves the same measurement goal with significantly reduced computational complexity.
2Device complexity
If subspace PIV method is used for DOA estimation, then device complexity is reduced, but measurement precision deteriorates due to unclear physical meaning
Solution Approach 1:
The patent introduces the intensity vector as an intermediary quantity that bridges the gap between the simplified PIV method and accurate DOA estimation. By defining the intensity vector in terms of spherical harmonic coefficients and computing it directly, the method provides a clear physical interpretation (energy flow direction) that restores measurement precision while maintaining low computational complexity.
3Measurement precision
If higher-order SHCs are incorporated for sound field analysis, then measurement precision is improved, but device complexity increases due to radial dependency
Solution Approach 1:
The patent extracts the essential directional information from higher-order spherical harmonic coefficients by computing only the intensity vector and energy density, eliminating the need to process all radial dependencies. This selective extraction maintains the benefits of higher-order SHCs for accurate sound field characterization while removing the computational burden of radial processing.
Data Source
AI summary
Embodiments according to the invention comprise a signal characteristic determinator, e.g. a calculator or an estimator, wherein the signal characteristic determinator is configured to determine an information about a characteristic of a sound field, e.g. a direction-of-arrival information or a diffuseness information, on the basis of higher-order, e.g. order larger than 1, spherical harmonic coefficients, also designated as SHCs, of a sound pressure, e.g. p(k), which may, for example, form the basis for Φp(k), and/or of a particle velocity and on the basis of spherical-harmonic-order dependent weights, e.g. weights g which determine the matrix G. Further embodiments of the invention comprise a signal characteristic determinator configured to determine an information about a characteristic of a sound field on the basis of higher-order circular harmonic coefficients of a sound pressure and/or of a particle velocity and on the basis of circular-harmonic-mode dependent weights.