NLOS Sound Source Localization via Diffraction-Aware Acoustic Ray Tracing
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Solution Overview
Problem
Current sound source localization methods face challenges in accurately localizing a 3D position of a sound source in real environments, especially when obstacles are present between the sound source and the microphone, as they struggle to differentiate between direct and indirect sound signals.
Innovation Solution
The method involves a computer-based system using a microphone array to collect audio signals, generating acoustic rays through reflection-aware and diffraction-aware acoustic ray tracing, and estimating the 3D position of the sound source by tracing these rays, even when obstacles are present, by reconstructing the indoor space and employing Monte-Carlo localization algorithms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sound source localization methods are used, then the system can operate in simple environments, but it fails to accurately localize sound sources when obstacles are present between the sound source and microphone
Solution Approach 1:
The patent segments the received audio signal into direct sound components and indirect sound components (reflections and diffractions) based on their arrival times and propagation characteristics. By separating these components, the system can independently analyze the direct sound for accurate sound source localization while using indirect sound information to infer obstacle positions and properties, thereby maintaining localization accuracy in environments with obstacles.
Solution Approach 2:
The patent extends the localization problem from traditional 2D horizontal plane to full 3D space by incorporating vertical angle information and distance estimation. The system uses the relationship between direct sound and indirect sound arrival times, combined with spatial distribution of microphone arrays, to calculate three-dimensional positions of sound sources, enabling accurate localization even when obstacles block direct line-of-sight paths.
2Measurement precision
If the system attempts to distinguish between direct and indirect sound signals, then localization accuracy improves, but the computational complexity and processing time increase
Solution Approach 1:
The patent performs preliminary processing of the audio signal by first identifying and marking the arrival time of the direct sound component, then using this reference point to systematically search for and classify indirect sound components. This preliminary action of establishing a time reference framework simplifies subsequent signal separation and reduces computational burden compared to analyzing all signal components simultaneously.
Solution Approach 2:
The patent implements a practical signal separation approach that focuses on identifying the most significant direct and indirect sound components rather than attempting to separate every possible reflection and diffusion. By processing only the dominant sound paths that contribute most to localization accuracy, the system achieves high measurement precision while avoiding the excessive computational complexity of complete signal decomposition.
3Ease of manufacture
If sequential sound signals are generated in a stationary sound source, then data accumulation is simplified, but the method is limited to situations where no obstacle is present between the sound source and microphone
Solution Approach 1:
The patent introduces indirect sound components (reflections off walls, ceilings, and diffractions around obstacles) as intermediary information sources. These indirect sounds, which naturally occur in environments with obstacles, are processed to provide additional spatial information about the sound source position and obstacle characteristics, enabling the system to overcome the limitation of requiring direct line-of-sight while maintaining ease of data collection from a stationary sound source.
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 allows for accurate estimation of a sound source's position in indoor spaces, including non-line of sight scenarios, by effectively distinguishing between direct and indirect sound signals, enabling precise localization even with obstacles in between.
Implementation Method 1
generating acoustic rays through reflection-aware acoustic ray tracing based on the collected audio signal
Implementation Method 2
estimating a position of an NLOS sound source based on a point at which one of the acoustic rays is diffracted
Data Source
AI summary
Disclosed is a method and system for diffraction-aware non-line of sight (NLOS) sound source localization (SSL) that may reconstruct an indoor space, may generate acoustic rays into the indoor space based on an audio signal collected from the indoor space, and may estimate a position of an NLOS sound source based on a point at which one of the acoustic rays is diffracted.