Audio Recognition False Positive Reduction via Sound Class Comparison

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Solution Overview

Problem

Existing audio recognition systems face challenges in accurately distinguishing between naturally emitted sounds and artificially emitted sounds, leading to 'false positives' and loss of user confidence, particularly in home security applications, due to the complexity of sound mixtures captured by microphones.

Innovation Solution

The proposed method employs a combination of two recognition engines to differentiate sound events by analyzing audio signals from both omnidirectional and directional microphones, allowing for more accurate discrimination of naturally emitted sounds from artificially emitted sounds at a higher symbolic level after initial recognition, independent of environmental parameters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If low level signal processing techniques with subtractor circuitry are used to cancel artificial sounds, then artificial sounds can be reduced in the processed output audio signals, but the system requires many parameter adjustments that are highly dependent on environmental factors and provide only poor or mixed results

Engineering Contradiction:
Improvesound discrimination accuracyVSAvoidparameter adjustment complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical signal processing approach (subtractor circuitry operating on audio signals) with an information processing approach (machine learning model operating on sound class labels). Instead of manipulating audio waveforms directly, the system uses trained models to classify sounds and compare class labels, eliminating the need for complex parameter adjustments related to gain, phase, and echo cancellation.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operating parameters from continuous audio signal values requiring precise gain and phase adjustment to discrete sound class labels that can be directly compared. The machine learning models output probability distributions over sound classes, which are then compared at the class level rather than requiring pixel-perfect signal subtraction.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If subtractor circuitry is used to process audio signals captured by microphones, then artificial sounds can be cancelled, but the unpredictable mix of real-life and artificial sounds in terms of amplitude, phase, and echoes makes subtraction very difficult to properly perform

Engineering Contradiction:
Improvefalse positive reductionVSAvoidsound separation accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent applies preliminary action by training machine learning models beforehand to recognize and classify different sound types. Instead of attempting to separate sounds in real-time through complex signal processing, the system pre-trains models to identify sound characteristics, then uses these pre-trained models to classify sounds and compare class labels, which is much more reliable than real-time signal subtraction.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces sound class labels as an intermediary between the raw audio signals and the final discrimination decision. Rather than directly comparing and subtracting audio signals which are mixed in unpredictable ways, the system uses machine learning models to translate signals into class labels, then compares these labels to determine whether a sound is artificial or real-life.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Productivity

If audio recognition systems rely on low level signal processing to differentiate real-life sounds from apparatus-generated sounds, then some artificial sounds can be filtered, but the systems generate a lot of false positives notified to the end user

Engineering Contradiction:
Improvesound processing efficiencyVSAvoidsound recognition accuracy
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent moves the discrimination problem from the signal amplitude dimension to the sound class label dimension. Instead of trying to separate sounds by manipulating their physical properties (amplitude, frequency, phase), the system classifies sounds into categories and performs discrimination at the class level, adding a categorical dimension to the analysis that is much more effective for distinguishing artificial from real-life sounds.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Data Source

PatentEP4066244B1Method for recognizing at least one naturally emitted sound produced by a real-life sound source in an environment comprising at least one artificial sound source, corresponding apparatus, computer program product and computer-readable carrier medium
Publication Date: 2024.09.25 THOMSON LICENSING SA
  • EP4066244B1 patent drawingFigure 1
  • EP4066244B1 patent drawingFigure 2
  • EP4066244B1 patent drawingFigure 3

AI summary

The disclosure relates to a method for recognizing at least one naturally emitted sound produced by a real-life sound source in an environment comprising at least one artificial sound source (ASSr). The method is implemented by an audio recognition device, and it includes simultaneously obtaining (11) a first audio signal from a first microphone (MIC) located in the environment and a second audio signal from an audio acquisition device (AAD) associated with the at least one artificial sound source; analyzing (12) the first audio signal, delivering a first list of sound classes (LI) corresponding to sounds recognized in the first audio signal; analyzing (13) the second audio signal, delivering a second list of sound classes (L2) corresponding to sounds recognized in the second audio signal; and delivering (14) a third list of sound classes (L3), comprising only sound classes included in the first list of sound classes (LI) which are not included in the second list of sound classes (L2).