In-Ear Noise Dosimeter with Direct Ear Canal Microphone
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Solution Overview
Problem
Current noise dosimeters are unable to accurately measure sound pressure levels in the ear canal, especially when an earpiece or headset is used, leading to significant differences in measurement compared to shoulder-based measurements, which can impact hearing health.
Innovation Solution
A microphone adapter and in-ear microphone system that allows direct sound pressure level assessment in the ear canal, using a MEMS microphone positioned within the ear canal to receive sound signals without intervening conduits, and an in-line noise detector to isolate sound from ambient noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a shoulder-based noise dosimeter is used, then the device is lightweight and portable, but it cannot accurately measure sound pressure levels in the ear canal when an earpiece or headset is used
Solution Approach 1:
The patent nests the measurement system within the earpiece itself. The earpiece housing contains the microphone and electronics, allowing the measurement device to be integrated into the existing earpiece structure rather than requiring a separate shoulder-based system. This nesting enables accurate in-ear measurement while maintaining portability.
Solution Approach 2:
The patent introduces an intermediary processing system that receives raw microphone signals from the earpiece and performs digital signal processing to isolate communication device noise from ambient noise. This intermediary processing layer enables accurate measurement by separating the different sound sources through algorithmic analysis.
2Measurement precision
If sound is transmitted through conduits or tubes to the microphone, then the microphone can be positioned outside the ear canal, but the sound measurement is distorted due to conduit physical properties
Solution Approach 1:
The patent extracts the microphone from any conduit or tube structure and positions it directly in the ear canal where the sound measurement is needed. By eliminating the intermediate transmission medium (conduit), the system avoids the distortion that would be introduced by conduit length, diameter, mass, and stiffness properties.
Solution Approach 2:
The patent replaces the mechanical sound transmission system (conduits and tubes) with direct acoustic coupling. The microphone diaphragm is positioned to directly receive sound pressure waves from the ear canal without mechanical transmission through intermediate structures, thereby eliminating mechanical distortion.
3Measurement precision
If an in-ear microphone is used to measure sound directly in the ear canal, then accurate sound pressure level measurement is achieved, but the microphone may contact the ear canal wall causing discomfort
Solution Approach 1:
The patent applies local quality by positioning the microphone diaphragm to face a specific location in the ear canal (anterior or posterior wall) rather than making contact with the wall itself. The measurement is taken at a localized position that is close to the wall but maintains a small clearance, providing accurate measurement without contact discomfort.
Solution Approach 2:
The patent incorporates an earpiece adapter that is pre-configured with the microphone positioning mechanism. The adapter is designed beforehand to maintain the correct clearance distance from the ear canal wall, ensuring that the microphone is positioned optimally for measurement without requiring adjustment during use, thus preventing discomfort.
4Loss of information
If ambient noise is included in the measurement, then the overall noise environment is captured, but the sound from the in-ear communications device cannot be isolated
Solution Approach 1:
The patent uses feedback by continuously monitoring the microphone signal and using digital signal processing to identify and subtract the ambient noise component. The system analyzes the characteristics of the captured sound and separates the communication device output from ambient noise based on their different acoustic signatures, providing isolated measurement of the communication device sound.
Solution Approach 2:
The patent performs preliminary characterization of the earpiece acoustic path and ambient noise properties before actual measurement. By pre-establishing the acoustic transfer function and noise profiles, the system can later isolate the communication device sound from ambient noise through computational methods, enabling separation without requiring complex real-time processing.
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 accurate and undistorted sound pressure level measurements directly from the ear canal, reducing the impact of sound transmission properties and ambient noise, thus improving the assessment of noise exposure.
Implementation Method 1
The microphone may be a MEMS microphone
Data Source
AI summary
An in-ear microphone allowing assessment of sound pressure level directly of an individual's ear canal without intervening conduits between the sound source (i.e., ear canal) and the microphone is provided. Sound from an in-ear communications device may also be isolated from ambient noise using an in-line noise detector for recording the noise from the in-ear communications device.