Breathing Apparatus Audio Filtering for Purge Noise Speech

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Solution Overview

Problem

Conventional voice communication systems in respiratory protection devices are severely degraded by purge noise, leading to undesirable communication disruptions when the purge valve is actuated, as they often disable voice transmission during such events.

Innovation Solution

A breathing apparatus with an audio processing unit that determines the state of the purge valve (open or closed) and applies different filters to audio signals based on this state, allowing speech transmission while suppressing purge noise by using distinct frequency responses for purge-off and purge-on states.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the purge valve is actuated to provide sufficient breathing gas flow, then the breathing gas supply is improved, but loud purge noise is generated inside the facepiece

Engineering Contradiction:

Improvebreathing gas flowVSAvoidpurge noise

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent detects purge noise and uses it as a signal to switch filter configurations, converting the harmful noise into useful information that triggers adaptive audio processing to maintain communication quality during purge events

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The audio processing system dynamically switches between different filter configurations based on real-time detection of purge valve state, adapting the frequency response characteristics to match current operating conditions and maintain speech intelligibility

Inventive Principle:

Principle #15Dynamics

2Object-affected harmful factors

If conventional voice communication systems disable transmission during purge events, then purge noise transmission is reduced, but voice communication is disrupted

Engineering Contradiction:

Improvepurge noise transmissionVSAvoidvoice communication

Core Design Contradiction:

Object-affected harmful factorsVSLoss of information

Solution Approach 1:

The system dynamically adjusts filter configuration based on detected purge valve state, switching between first filter configuration during normal operation and second filter configuration during purge events to maintain communication while managing noise

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system continuously monitors audio signals to detect purge noise characteristics and uses this feedback to automatically switch between different filter configurations, maintaining optimal communication quality without manual intervention

Inventive Principle:

Principle #23Feedback

3Device complexity

If a single filter configuration is used for all operating states, then device complexity is reduced, but communication quality is degraded during state transitions

Engineering Contradiction:

Improveaudio processing systemVSAvoidspeech transmission quality

Core Design Contradiction:

Device complexityVSLoss of information

Solution Approach 1:

The audio processing unit dynamically selects between multiple filter configurations based on real-time detection of operating state, adapting the frequency response to match current conditions and maintain speech intelligibility across different operational scenarios

Inventive Principle:

Principle #15Dynamics

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 clear speech communication even when the purge valve is actuated, effectively reducing purge noise interference and maintaining effective voice transmission.

Implementation Method 1

applying a first filter on the audio signal if the determined state is the first state. The first filter has a first frequency response. The audio processing unit is further configured to apply a second filter on the audio signal if the determined state is the second state. The second filter has a second frequency response different from the first frequency response

Methodology Applied

Scientific EffectFrequency filtering: Filter (electronic)

Data Source

PatentUS20250375629A1Breathing apparatus and method of communicating using breathing apparatus

Publication Date: 2025.12.11 3M INNOVATIVE PROPERTIES CO

AI summary

A method of communicating using a breathing apparatus includes receiving an audio signal from a sound acquisition unit. The method further includes determining a state of the breathing apparatus based on the received audio signal. The state is at least one of a first state and a second state. The method further includes applying a first filter on the audio signal if the determined state is the first state. The first filter has a first frequency response. The method further includes applying a second filter on the audio signal if the determined state is the second state. The second filter has a second frequency response different from the first frequency response of the first filter. The method further includes generating an output signal based on the application of the first filter or the second filter. The method further includes receiving the output signal at an output device.