Breathing Mask Microphone Acoustic Filter
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Breathing masks equipped with communication devices face poor internal acoustics and significant background noise, leading to speech degradation during radio transmission, which can result in communication failures, especially in critical situations like firefighting.
Innovation Solution
An electro-acoustical transducer device with a differential microphone and a chamber-channel configuration that acts as a high-pass filter, reducing low-frequency noise without the need for an electrical filter, using a vented cover element and acoustical resistor elements to achieve desired frequency responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an electrical filter is connected to the output of the microphone to suppress noise frequencies, then speech clarity is improved, but power consumption increases
Solution Approach 1:
The patent replaces the electrical filter system with an acoustic filter system. The acoustic filter consists of a chamber with specific volume and openings that acoustically modify the sound waves before they reach the microphone, eliminating the need for electrical filtering and its associated power consumption while maintaining speech clarity.
Solution Approach 2:
The patent introduces an acoustic filter as an intermediary component between the microphone and the audio signal processing system. This acoustic filter, implemented through a chamber with specific geometry and openings, pre-processes the sound waves to reduce noise frequencies before they enter the microphone, thereby reducing the burden on subsequent electrical processing and eliminating the need for power-consuming electrical filters.
2Reliability
If the microphone is positioned to capture clear speech, then speech quality is improved, but sensitivity to background noise increases
Solution Approach 1:
The acoustic filter acts as an intermediary that selectively allows speech frequencies to pass while attenuating background noise frequencies before they reach the microphone. The chamber geometry and openings are designed to create frequency-selective acoustic paths that enhance speech intelligibility while reducing the microphone's sensitivity to irrelevant background sounds.
Solution Approach 2:
The patent applies local quality by creating specific acoustic environments in different parts of the mask. The chamber and openings are positioned and dimensioned to provide localized acoustic filtering at the microphone interface, allowing the microphone to operate in a controlled acoustic environment that enhances speech capture while minimizing noise sensitivity.
3Reliability
If the internal acoustics of the breathing mask are improved, then speech clarity is improved, but device complexity increases
Solution Approach 1:
The acoustic filter chamber serves multiple functions simultaneously: it acts as a noise filter, a sound wave modifier, and an integral part of the mask structure. By combining these functions into a single multi-functional component, the patent improves speech clarity without proportionally increasing device complexity, as the same structural element achieves multiple acoustic objectives.
Solution Approach 2:
The patent merges the acoustic filtering function with the existing mask structure. The chamber and openings are integrated into the mask body rather than being separate add-on components, thereby improving speech clarity while minimizing the increase in overall device complexity through structural integration.
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
Significantly reduces low-frequency noise and mechanical excursion, enhancing speech clarity and preventing distortion, even at high volumes, without the power consumption of an electrical filter, ensuring clear communication in noisy environments.
Implementation Method 1
the differential microphone comprises a front side for receiving an acoustical signal and a rear side for receiving the acoustical signal in modified form and the differential microphone is arranged to produce an electrical output signal substantially proportional to a difference of the acoustical signal at the front side and the acoustical signal at the rear side
Implementation Method 2
the body structure is arranged to form a chamber shared with the rear side of the differential microphone and there is at least one tubular channel in the first wall of the body structure to the chamber so that the at least one channel and the chamber constitute an acoustical filter for filtering the acoustical signal received by the rear side of the differential microphone
Implementation Method 3
The combination of the chamber and the channels can be dimensioned, i.e. tuned, so that the acoustical filter is a low-pass filter which is applied to the acoustical signal received by the rear side of the differential microphone
Data Source
AI summary
An electro-acoustical transducer device includes a body structure (101) and a differential microphone (102) located in an aperture of a wall of the body structure. The microphone includes a front side for receiving an acoustical signal and a rear side for receiving the acoustical signal in modified form. The differential microphone is arranged to produce an electrical output signal proportional to the difference of the acoustical signals at the front and rear sides. The body structure is arranged to form a chamber (105) shared with the rear side of the microphone. There are tubular channels (107) to the chamber so that the channels and the chamber constitute an acoustical filter for filtering the acoustical signal falling to the rear side of the microphone. With proper design of the chamber and the channels, it is possible to achieve acoustical filtering for background noise rejection.