Acoustic Source Localization Through Direct-Reflection Separation
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Solution Overview
Problem
Existing methods for acoustic source localization using ambisonic microphones are biased by direct sound interference with reflections, particularly when placed near walls, and lack effective distance estimation from a single capture point, leading to inaccurate angular and 3D location determination.
Innovation Solution
A method utilizing a general velocity vector V′(f) that accounts for both direct and reflected acoustic paths, incorporating a reference component D(f) in the denominator, allowing for iterative calculations to determine direction of arrival (DoA), distance d0 to the microphone, and distance z0 to the wall, enhancing accuracy and robustness in reflective environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional velocity vector methods are used for acoustic source localization, then the processing is simpler, but the estimation accuracy deteriorates due to bias from direct sound interference with reflections
Solution Approach 1:
The patent segments the acoustic signal into direct sound components and reflected sound components by analyzing the velocity vector in the frequency domain. This segmentation allows separate processing of direct and reflected paths, enabling accurate source localization even in reflective environments by isolating the direct sound contribution from the total acoustic field
Solution Approach 2:
The patent introduces an intermediary reference signal that represents the direct sound path. This reference signal acts as a mediator between the observed velocity vector and the estimated source location, allowing the system to separate direct and reflected components through correlation analysis and improve estimation accuracy without requiring complex array geometries
2Measurement precision
If a single capture point is used, then the device complexity is reduced, but the ability to estimate distance and 3D location deteriorates
Solution Approach 1:
The patent transitions from spatial domain analysis to frequency domain analysis by applying Fourier transform to the velocity vector. This dimensionality change from time/space to frequency domain enables distance estimation and 3D localization using a single capture point, as the frequency domain representation reveals phase and amplitude information that encodes spatial characteristics including distance to the source
3Measurement precision
If the microphone is placed near walls, then the compactness is maintained, but the localization accuracy deteriorates due to reflection interference
Solution Approach 1:
The patent converts the harmful effect of wall reflections into a beneficial feature by using the velocity vector's frequency domain characteristics. The method analyzes how reflections affect the velocity vector at different frequencies and uses this information to identify and compensate for reflection-induced biases, ultimately improving angular location estimation accuracy even in near-wall positions
Solution Approach 2:
The patent changes the analysis parameter from time domain to frequency domain by applying Fourier transform. This parameter change reveals frequency-dependent characteristics of the velocity vector that allow differentiation between direct and reflected sound paths, enabling accurate DoA estimation despite the presence of reflections from nearby walls
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
The method provides more accurate and robust estimation of acoustic source parameters, including DoA and distances, by effectively separating direct and reflected sound components, reducing bias and improving 3D localization accuracy.
Implementation Method 1
a first acoustic path, direct between the source and the microphone, represented by a first vector U0, and at least a second acoustic path resulting from a reflection on the wall
Implementation Method 2
at least a second acoustic path resulting from a reflection on the wall and represented by a second vector U1
Data Source
AI summary
A method of processing audio signals acquired by at least one microphone to locate a sound source in a space having a wall. The method includes applying a time-frequency transform to the acquired signals and expressing a general complex velocity vector with a real part and an imaginary part in the frequency domain. The vector has a denominator with a component other than an omnidirectional component and characterizes a composition between: a first acoustic path, direct between the source and the microphone, represented by a first vector, and a second acoustic path resulting from a reflection on the wall and represented by a second vector. The second path has a delay relative to the direct path. A direction of the direct path, a distance from the source to the microphone, and/or a distance from the source to the wall is determined as a function of the delay and the vectors.