Electro-Acoustic Earplug Noise Dosimetry With Source Separation
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Solution Overview
Problem
Existing hearing protection devices (HPDs) fail to accurately measure in-ear noise exposure due to wearer-induced disturbances, background noise variations, and inadequate segregation of sound sources, leading to potential hearing damage and situational awareness issues.
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, ambient noise, and playback signals, providing real-time personal attenuation ratings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional hearing protection devices are used to reduce ambient noise, then noise exposure is reduced, but wearer-induced disturbances (speech, chewing) cannot be discriminated and contribute to measured sound pressure levels
Solution Approach 1:
The patent segments the sound pressure measurement into multiple independent components by using multiple microphones positioned at different locations (outer ear canal, inner ear canal) and applying independent digital signal processing to each microphone signal. This allows separate estimation and identification of ambient noise, wearer-induced disturbances, and playback sounds, resolving the contradiction between noise reduction and measurement precision.
Solution Approach 2:
The patent introduces an intermediary processing system consisting of digital signal processing algorithms that act as a mediator between the raw microphone signals and the final noise exposure assessment. This intermediary system separates the different sound sources through computational methods, enabling accurate measurement despite the presence of multiple simultaneous sound sources.
2Measurement precision
If in-car noise dosimeters with inner ear microphones are used to measure residual noise level, then in-ear sound pressure can be measured, but wearer-induced disturbances cannot be separated from other sound sources
Solution Approach 1:
The patent applies segmentation by dividing the sound field into distinct sources (ambient noise, wearer-induced disturbances, playback sounds) and processing each source separately through independent digital signal processing channels. This allows the system to maintain measurement precision while simultaneously discriminating between different sound sources that would otherwise be mixed together.
Solution Approach 2:
The patent adds a dimensional aspect by introducing multiple microphones at different spatial positions and multiple processing dimensions through digital signal processing. This multi-dimensional approach enables the system to distinguish between sound sources based on their temporal patterns, spectral characteristics, and spatial distribution, thereby separating information that would be lost in traditional single-microphone systems.
3Object-affected harmful factors
If hearing protection devices provide attenuation, then noise exposure is reduced, but situational awareness and communication are impaired
Solution Approach 1:
The patent segments the auditory information into different categories (ambient noise, communication signals, wearer-induced disturbances) and processes them through separate channels. This allows the system to maintain attenuation for harmful noise while selectively enhancing or preserving information relevant to situational awareness and communication, thereby resolving the contradiction between noise protection and awareness.
Solution Approach 2:
The patent applies local quality by providing different levels of processing and attenuation for different sound sources. Rather than uniform attenuation, the system applies selective processing where ambient noise is attenuated but communication signals and important environmental sounds are preserved or enhanced, allowing the wearer to maintain situational awareness while being protected from harmful noise.
4Adaptability or versatility
If background noise level rises above expectations, then previously suitable hearing protection becomes inadequate, but real-time adaptation is difficult
Solution Approach 1:
The patent implements dynamics by continuously monitoring the acoustic environment through multiple microphones and digitally signal processing to identify changes in background noise levels. The system dynamically adjusts its attenuation characteristics in real-time based on the detected noise environment, allowing previously suitable hearing protection to adapt to rising background noise levels and maintain adequacy.
Solution Approach 2:
The patent employs feedback mechanisms where the system continuously measures the actual noise exposure and compares it against safety thresholds and expected background noise levels. This feedback information is used to adjust the hearing protection characteristics in real-time, ensuring that the protection remains adequate as background noise levels change, thereby resolving the contradiction between adaptability and measurement precision.
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
Accurately measures and segregates sound sources in real-time, ensuring safe noise exposure levels and situational awareness by accounting for wearer-induced disturbances and varying noise environments.
Implementation Method 1
an inner ear microphone (IEM) adapted to capture a general sound pressure level (SPL) of the sound dose present in the ear canal
Implementation Method 2
an outer car microphone (OEM) adapted to capture the ambient sound
Implementation Method 3
an in-ear loudspeaker (IELS) configured to emit a playback signal in an ear canal of a wearer
Data Source
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.