Hearing Protection Microphone Sensitivity Check Using Ambient Sound

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Solution Overview

Problem

Hearing protection devices face challenges in accurately checking the relative sensitivity of their microphones, especially when they lack a speaker to generate a uniform sound field for both inner-ear and outer-ear microphones, leading to potential noise attenuation failures due to improper fitting or microphone degradation.

Innovation Solution

A method and device that utilize ambient sound to check the relative sensitivity of microphones by sampling audio samples, determining the adequacy of ambient noise, and providing a pass or fail indication based on threshold comparisons, using digital signal processing techniques to model the transfer function between microphones and reject disturbances.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a speaker is used to generate a uniform sound field for microphone sensitivity checking, then measurement precision is improved, but device complexity increases

Engineering Contradiction:

Improvemicrophone sensitivity checking accuracyVSAvoiddevice structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses ambient sound as an intermediary to perform microphone sensitivity checking without requiring a built-in speaker. The system captures ambient sound through the microphones and uses digital signal processing to analyze the relative sensitivity, thereby avoiding the need for additional hardware components while maintaining measurement capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The hearing protection device utilizes the ambient acoustic environment as a free resource for self-diagnosis. By processing ambient sound captured by its own microphones, the device performs sensitivity checking autonomously without external equipment, reducing device complexity while enabling regular monitoring of microphone performance.

Inventive Principle:

Principle #25Self-service

2Device complexity

If ambient sound is used for microphone sensitivity checking, then device complexity is reduced, but measurement precision deteriorates due to inadequate or inconsistent ambient noise

Engineering Contradiction:

Improvedevice structureVSAvoidmicrophone sensitivity checking accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The system performs preliminary assessment of ambient sound adequacy before conducting sensitivity measurements. It evaluates whether the ambient acoustic environment contains sufficient frequency content and signal strength, and only proceeds with measurement when conditions are suitable, thereby ensuring measurement precision despite using external sound sources.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system incorporates feedback mechanisms to monitor the quality of ambient sound and the results of sensitivity measurements. Based on this feedback, it can determine whether measurements are reliable and can trigger alerts or repeat measurements when ambient conditions are inadequate, maintaining measurement precision through continuous quality assessment.

Inventive Principle:

Principle #23Feedback

3Reliability

If relative sensitivity checking is performed daily, then reliability is improved by detecting microphone failures early, but loss of time increases due to frequent checking procedures

Engineering Contradiction:

Improvenoise attenuation performanceVSAvoidchecking procedure time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system implements periodic sensitivity checking at user-defined intervals (e.g., daily, weekly, or monthly) rather than continuously. This periodic approach maintains reliability by regularly detecting microphone failures while minimizing time loss by allowing the device to operate normally between checking intervals.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system performs quick sensitivity checks that may be less comprehensive than full diagnostic procedures but are sufficient for detecting obvious failures. By using partial checking routines that focus on critical parameters, it maintains reliability for early failure detection while reducing the time required for each checking operation.

Inventive Principle:

Principle #16Partial or excessive action

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

Enables a daily relative sensitivity check of hearing protection device microphones, ensuring accurate noise attenuation by detecting failures and rejecting false positives, thus maintaining reliable performance over time.

Implementation Method 1

two or more microphones configured to sense sound of an environment

Methodology Applied

Scientific EffectSound sensing: Sound

Data Source

PatentUS20240187804A1Field check for hearing protection devices

Publication Date: 2024.06.06 3M INNOVATIVE PROPERTIES CO

AI summary

Systems and methods for check a relative sensitivity of two or more microphones of a hearing protection device include sensing ambient sound using two or more microphones of the hearing protection device and sampling the ambient sound. The samples of the ambient sound may be used to determine whether the ambient sound is adequate for determining microphone sensitivity and to determine whether a threshold relative sensitivity of the two or more microphones is reached. A pass or fail indication may be provided to a user based on whether the threshold relative sensitivity is reached.