TDOA Localization Using Direct Sound Extraction

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Solution Overview

Problem

Traditional methods for localizing acoustic signals in augmented reality environments are prone to errors due to environmental distortions and reverberations, leading to inaccurate determination of spatial coordinates.

Innovation Solution

A system utilizing a plurality of microphones with a time-difference-of-arrival (TDOA) module to process audio signals, distinguishing direct sounds from reverberations and echoes, and using known physical attributes to filter TDOA results, thereby generating accurate TDOA data for hyperbolic positioning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional TDOA methods are used to determine spatial coordinates of acoustic signals, then the system can process acoustic signals in augmented reality environments, but the localization accuracy deteriorates due to environmental distortions and reverberations

Engineering Contradiction:
Improvelocalization accuracyVSAvoidenvironmental distortions and reverberations
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent extracts and isolates the direct sound component from the mixed acoustic signal by analyzing the initial arrival time and characteristics of sound waves. The system separates direct sound from reverberations and echoes, using only the direct sound portion for TDOA calculation to eliminate distortion effects.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The system performs preliminary filtering and identification of direct sound components before conducting TDOA calculations. By pre-processing the acoustic signals to identify and isolate direct sound arrivals, the system prepares clean data for accurate localization without contamination from later reverberations.

Inventive Principle:
Principle #10Preliminary action

2Quantity of substance

If all acoustic signal components are used for TDOA calculation, then more data is available for processing, but measurement precision deteriorates due to inclusion of reverberations and echoes

Engineering Contradiction:
Improveamount of acoustic dataVSAvoidTDOA estimation accuracy
Core Design Contradiction:
Quantity of substanceVSMeasurement precision

Solution Approach 1:

The patent extracts only the relevant direct sound portion from the complete acoustic signal. By identifying the initial arrival time and separating direct sound from subsequent reverberations, the system uses a subset of the total acoustic data that is free from distortion, improving TDOA estimation accuracy.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The system applies different processing quality to different portions of the acoustic signal. The initial direct sound portion is processed with high priority for TDOA calculation, while later reverberating portions are excluded or given lower weight, ensuring that only high-quality undistorted data contributes to localization.

Inventive Principle:
Principle #3Local quality

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 minimizes errors caused by reverberations, providing accurate localization of acoustic signals by focusing on direct sound components and using physical attributes to constrain TDOA results, enhancing the precision of spatial coordinate determination.

Implementation Method 1

A time-difference-of-arrival (TDOA) module 120 is configured to generate from the audio signals a set of time delays

Methodology Applied
Scientific EffectTime difference of arrival: Time of Flight

Implementation Method 2

distinguishing direct sounds from reverberations and echoes, and using known physical attributes to filter TDOA results

Methodology Applied
Scientific EffectDirect sound propagation: Sound

Implementation Method 3

Traditional methods of localizing, or determining the spatial coordinates, of an acoustic source are sensitive to distortions introduced by the environment and frequently produce erroneous results

Methodology Applied
Scientific EffectReverberation: Reverberation

Data Source

PatentEP2724554B1Time difference of arrival determination with direct sound
Publication Date: 2019.06.05 AMAZON TECH INC
  • EP2724554B1 patent drawingFigure 1
  • EP2724554B1 patent drawingFigure 2
  • EP2724554B1 patent drawingFigure 3

AI summary

Acoustic signals may be localized such that their position in space is determined. Time-difference-of-arrival data from multiple microphones may be used for this localization. Signal data from the microphones may be degraded by reverberation and other environmental distortions, resulting in erroneous localization. By detecting a portion of the signal resulting from sound directly reaching a microphone rather than from a reverberation, accuracy of the localization is improved.