In-Ear Sound Dose Limiting for Accurate Hearing Exposure Control
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Solution Overview
Problem
Existing earpiece devices fail to accurately measure and manage sound exposure, leading to potential hearing loss due to variations in earpiece positioning and neglect of auditory fatigue, and they do not effectively transmit natural voice signals in noisy environments.
Innovation Solution
An earpiece device with internal and external microphones calculates a cumulative total sound dose, displays remaining listening time, and adjusts audio output to prevent exceeding safe thresholds, while also allowing ambient sound monitoring and natural voice signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If earpiece devices use estimated total noise dose integration based on speaker output and environmental noise, then hearing protection can be provided, but measurement precision deteriorates because earpiece positioning varies considerably among users
Solution Approach 1:
An ear canal microphone is introduced as an intermediary device to directly measure the actual sound pressure level inside the user's ear canal. This mediator bypasses the estimation problem by providing direct measurement of the sound exposure at the critical location (eardrum), thereby resolving the contradiction between reliable hearing protection and precise measurement.
2Ease of operation
If users wear headphones to listen to music, then entertainment is provided, but harmful factors increase due to acoustic disconnection from surrounding ambient sounds
Solution Approach 1:
The system continuously monitors the actual sound pressure level inside the ear canal and provides feedback to the user through visual or haptic alerts when safe listening thresholds are approached or exceeded. This feedback mechanism allows users to maintain music listening convenience while being aware of and adjusting their exposure to prevent harmful effects.
Solution Approach 2:
The device calculates and displays remaining safe listening time before the maximum acceptable sound dose is reached, allowing users to take preliminary action (reduce volume, take breaks) before hearing damage occurs, thus preventing harmful effects while maintaining listening enjoyment.
3Object-affected harmful factors
If internal microphones are used for voice pickup, then noise reduction is achieved, but voice naturalness deteriorates due to occlusion effect transforming higher frequencies into lower frequencies
Solution Approach 1:
The ear canal microphone serves as an intermediary that captures the user's voice naturally as it occurs in the ear canal, before being transformed by body parts. This direct measurement approach preserves voice naturalness while still providing noise reduction capabilities through proper signal processing.
Solution Approach 2:
Instead of trying to correct the occlusion effect after it transforms the voice signal, the invention measures the voice signal before the transformation occurs (in the ear canal), thereby capturing the natural voice characteristics. This inverted approach of measuring at the source rather than at the output resolves the contradiction between noise reduction and voice naturalness.
4Device complexity
If earpiece devices do not account for auditory fatigue recuperation, then device complexity is reduced, but reliability deteriorates because the human ear rests and recuperates from auditory fatigue over time
Solution Approach 1:
The system dynamically adjusts the sound dose calculation by incorporating auditory fatigue recuperation factors. The remaining safe listening time is not based on static thresholds but on dynamic models that account for the ear's ability to recover from fatigue over time, especially when sound pressure levels are relatively low. This dynamic approach improves reliability without excessive complexity.
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
Effectively manages sound exposure to prevent hearing damage, provides accurate auditory feedback, and ensures clear voice transmission by calculating sound doses and adjusting audio levels, and enhances voice clarity in noisy conditions.
Implementation Method 1
an ear canal microphone for measuring a sound pressure level in an ear canal of the user
Implementation Method 2
an ambient sound microphone, an ear canal receiver and an ear canal microphone to actively monitor a sound exposure level inside the ear canal
Data Source
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AI summary
The invention relates to a sound dose limiter device for controlling a total sound dose reaching an ear of a user, said limiter device comprising: - an in-ear device for substantially occluding an outer ear canal of the user, said in-ear device including a speaker for providing an audio signal input from an audio output of an audio source inside the outer ear canal, an internal microphone for measuring a sound pressure level inside the occluded outer ear canal, and an external microphone for measuring an external ambient sound pressure level reaching the user's ear; and - a controller device connecting to the internal and external microphones for receiving respective internal and external measured sound pressure levels and for receiving the audio output, said controller device performing an evaluation of the internal and external measured sound pressure levels, calculating a cumulative total sound dose from the internal sound pressure level and the audio signal input depending on the evaluation, and decreasing the audio signal input transmitted to the speaker based on the calculated cumulative total sound dose approaching a maximum acceptable sound dose threshold.