Electro-Acoustic Earplug Noise Dosimetry with Source Separation

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Solution Overview

Problem

Existing in-ear noise dosimeters fail to accurately measure noise exposure under hearing protection devices (HPDs) due to wearer-induced disturbances, inability to segregate sound sources, and incompatibility with advanced HPDs featuring in-ear loudspeakers, leading to inadequate protection and potential hearing damage.

Innovation Solution

A system and method using electro-acoustic earplugs with inner and outer ear microphones, an in-ear loudspeaker, and adaptive digital filters to separate and correct sound contributions from various sources, including wearer-induced disturbances, to accurately estimate personal attenuation rating (PAR) and residual noise levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If an inner ear microphone (IEM) is used to measure residual noise level under the HPD, then in-ear noise dosimetry becomes possible, but wearer-induced disturbances (speech, chewing noise) contaminate the measurement due to the occlusion effect

Engineering Contradiction:

Improveresidual noise level measurementVSAvoidwearer-induced disturbances

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent segments the total sound signal captured by the IEM into distinct components: ambient noise, playback signal, and wearer-induced disturbances. By separating these sources, the system can accurately measure residual ambient noise while excluding contamination from speech and chewing sounds.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary processing system that uses transfer function modeling to estimate what the IEM would hear without wearer-induced disturbances. This intermediary model acts as a filter to remove harmful components while preserving the measurement of actual ambient noise exposure.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If advanced HPDs with in-ear loudspeakers (IELS) are used to provide communication and audio signals, then situational awareness and communication are improved, but the ability to measure accurate noise exposure is compromised

Engineering Contradiction:

Improvecommunication and audio playback capabilityVSAvoidnoise exposure measurement

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent extracts the playback signal component from the total IEM measurement by using the known output signal from the IELS and the measured transfer function. This extraction allows the system to isolate and measure only the residual ambient noise, maintaining measurement precision while enabling advanced HPD features.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent creates a multi-functional system where the same electro-acoustic HPD provides both audio playback/communication capabilities and accurate noise dosimetry. The system universally handles multiple functions through integrated microphones, loudspeakers, and processing algorithms that work together.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Measurement precision

If current in-ear dosimeters are used, then noise exposure measurement is possible, but they cannot segregate contributions from various sound sources (ambient noise, playback, wearer-induced disturbances)

Engineering Contradiction:

Improvenoise exposure measurementVSAvoidsound source discrimination

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

The patent segments the composite sound signal into distinct source components using transfer function modeling and signal processing. By separating ambient noise, playback signals, and wearer-induced disturbances into individual measurable components, the system preserves information about each source while maintaining overall measurement accuracy.

Inventive Principle:

Principle #1Segmentation

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

Provides real-time, accurate measurement of noise exposure by segregating and correcting sound sources, ensuring effective hearing protection and situational awareness without over- or under-attenuation, thereby reducing the risk of hearing damage.

Implementation Method 1

an inner ear microphone (IEM) adapted to capture a canal sound pressure level (SPL) of the sound dose present in the ear canal

Methodology Applied

Scientific EffectAcoustic to electrical transduction:

Implementation Method 2

an outer ear microphone (OEM) adapted to capture the ambient sound

Methodology Applied

Scientific EffectAcoustic to electrical transduction:

Implementation Method 3

an in-ear loudspeaker (IELS) configured to emit an audio signal in an ear canal of a wearer

Methodology Applied

Scientific EffectElectrical to acoustic transduction:

Implementation Method 4

adaptive digital filters to separate and correct sound contributions from various sources

Methodology Applied

Scientific EffectAdaptive digital filtering: Filter (electronic)

Data Source

PatentUS12413920B2System and method to perform in-ear noise dosimetry and personal attenuation rating under an electro-acoustic earplug while excluding wearer-induced disturbances and separating exposure sources

Publication Date: 2025.09.09 ECOLE DE TECH SUPERIEURE

AI summary

A system and method to measure noise reduction and evaluate the contributions of various sound sources to noise exposure dose of exposition using electro-acoustic earplugs is provided. The system may be implemented as an advanced HPD in the form of an electro-acoustical earplug. The earplug comprises an OEM 10 and an IEM. The system is configured to calculate an estimated IEM signal based on calculation of estimates of residual ambient noise, payback sounds or WID present in the ear canal.