Acoustic Source Localization Using Velocity Vector Segmentation
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Solution Overview
Problem
Existing methods for acoustic source localization, particularly in ambisonic systems, face challenges in accurately determining the direction of arrival (DoA) and distance of acoustic sources due to interference from direct sound and reflections, leading to biased estimates and inability to effectively handle complex acoustic environments.
Innovation Solution
The method models interference between direct and indirect waves using the velocity vector's real and imaginary parts, applying inverse transforms to express the vector in the time domain and determining relevant parameters such as direction and distance by analyzing peaks associated with direct and reflected paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If vector-based methods (DirAC, VVM) are used for acoustic source localization, then the direction of arrival can be estimated, but the estimates are biased due to interference from direct sound and reflections
Solution Approach 1:
The patent segments the velocity vector into real and imaginary parts, and further segments the temporal signal into direct sound and reflection components. By analyzing the real part for direction and the imaginary part for distance, the method separates directional information from distance information, allowing independent optimization of each parameter's accuracy while reducing mutual interference and estimation bias.
Solution Approach 2:
The patent transitions from traditional 2D angular direction estimation to 3D localization by incorporating distance estimation as a third dimension. This is achieved by utilizing the imaginary part of the velocity vector in the time domain, which provides distance information complementary to the directional information from the real part, thereby improving overall localization accuracy in reflective environments.
2Device complexity
If traditional methods ignore the imaginary part of the velocity vector, then calculation is simpler, but distance information is lost and localization accuracy deteriorates
Solution Approach 1:
The patent segments the velocity vector into real and imaginary parts with distinct functional assignments: the real part is used for direction of arrival estimation, while the imaginary part is used for distance estimation. This segmentation allows the system to utilize both parts of the complex vector, extracting complementary information from each without significantly increasing overall computational complexity.
3Measurement precision
If sub-space methods and algorithms are used on large quantities of frequency sub-bands, then spatial resolution is improved, but computational cost increases significantly
Solution Approach 1:
The patent extracts only the essential information needed for localization from the complex velocity vector by separating real and imaginary parts and processing them through different pathways. This extraction approach avoids the computational burden of full sub-space methods while retaining the critical directional and distance information, thereby reducing computational cost without sacrificing spatial resolution.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides more accurate localization of acoustic sources in 3D space by effectively separating direct and reflected signals, reducing bias and enabling estimation of source distance, even in complex environments with multiple reflections.
Implementation Method 1
The patent models the interference of the direct wave with at least one indirect wave resulting from a reflection. The expression of the velocity vector makes it possible to highlight a first maximum corresponding to the direct wave and at least one second maximum corresponding to the indirect wave.
Data Source
Figure 1~2
Figure 3A
Figure 3B
AI summary
The invention relates to the processing of audio signals acquired by a least one microphone, of ambisonic type for example, with a view to locating at least one audio source in a space comprising at least one wall. A time-frequency transform is applied to the acquired signals and, on the basis of the acquired signals, a complex velocity vector V(f) with a real part and imaginary part is expressed in the frequency domain, the velocity vector characterising a composition between: * a direct first acoustic path between the source and the microphone, this path being represented by a first vector U0, and * at least one second acoustic path resulting from a reflection from the wall and represented by a second vector U1, the second path having, at the microphone, a first delay TAU1, with respect to the direct path. Depending on the delay TAU1, on the first vector U0 and on the second vector U1, at least one parameter among a direction (DoA) of the direct path, a distance d0 from the source to the microphone, and a distance z0 from the source to said wall is determined.