Thin Plate Pressure Attenuator for MEMS Microphones
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Solution Overview
Problem
Existing MEMS microphones are limited in dynamic range and prone to damage from high sound pressures, making them unsuitable for applications like noise dosimetry and military acoustic monitoring.
Innovation Solution
A thin plate pressure attenuator (TPPA) is introduced, which modifies the microphone's performance by uniformly attenuating pressure as a function of frequency and providing protection from environmental hazards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standard MEMS microphone is used, then the device is compact and low-cost, but the dynamic range is limited and the microphone is vulnerable to high sound pressure damage
Solution Approach 1:
The thin plate pressure attenuator is nested within the microphone housing, creating a nested structure where the attenuator occupies the space between the sound port and the microphone capsule. This nested arrangement allows the protective and range-extending function to be integrated within the existing microphone form factor without significantly increasing overall device complexity.
Solution Approach 2:
The thin plate acts as an intermediary element between the high-pressure external environment and the microphone membrane. It mediates the pressure transmission by attenuating high-frequency pressure waves while allowing lower-frequency sounds to pass through, thereby protecting the microphone from damage while maintaining audio functionality.
2Manufacturing precision
If the acoustic back cavity is made large to reduce acoustical impedance, then membrane vibration is improved, but the device volume increases
Solution Approach 1:
The thin plate pressure attenuator changes the acoustic parameters of the back cavity by introducing a compliant element that modifies the effective acoustic impedance. This allows the back cavity to maintain smaller dimensions while achieving the desired vibration performance through the parameter-modifying effect of the thin plate.
Solution Approach 2:
The thin plate functions as a flexible film that couples the back cavity to the sound port environment. This thin film structure provides acoustic compliance that effectively increases the acoustic volume without physically expanding the device, thereby maintaining compact dimensions while improving membrane vibration characteristics.
3Ease of operation
If the microphone is exposed to the ambient environment through the sound port, then audio signal capture is enabled, but the membrane is vulnerable to environmental hazards
Solution Approach 1:
The thin plate pressure attenuator serves as an intermediary barrier between the ambient environment and the microphone membrane. It allows audio frequency pressure waves to pass through for signal capture while blocking physical contaminants such as water, chemicals, and debris from reaching the membrane.
Solution Approach 2:
The thin plate acts as a protective film that seals the microphone membrane from environmental hazards while maintaining acoustic transparency. This thin film structure permits sound wave transmission for audio capture but provides physical protection against water ingress, chemical exposure, and particulate contamination.
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
The TPPA effectively shifts the dynamic range of microphones to handle higher sound pressures without distortion, while also protecting the microphone membrane from water, chemicals, and physical damage.
Implementation Method 1
a first acoustic cavity between the thin plate and the microphone; attenuating pressure waves
Data Source
AI summary
A thin plate pressure attenuator includes a housing and a thin plate attached to the housing. The housing and the thin plate together define a first acoustic sound cavity. The housing can include a base and an annular wall. A microphone can be acoustically coupled to the sound cavity.