MEMS Microphone Acoustic Filter for Wind Noise Reduction
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Solution Overview
Problem
Existing acoustic transducers in portable devices, such as mobile phones, face limitations in adapting to changing acoustic environments due to fixed mechanical designs, leading to inadequate wind noise reduction and increased processing power requirements for signal filtering.
Innovation Solution
A micro-electromechanical system (MEMS) microphone transducer with an electrically controllable mechanical acoustic filter, featuring a membrane and back plate with a moveable blocking member that can seal or open filter holes to adjust acoustic properties, reducing wind noise without significant processing power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If digital signal processing is used to filter wind noise, then wind noise reduction is achieved, but processing power requirements increase significantly
Solution Approach 1:
The patent replaces electrical/digital signal processing with a mechanical acoustic filter system. A moveable blocking member (plug) is positioned within a sound channel to physically obstruct wind flow paths, reducing wind noise at the acoustic level before it reaches the microphone element, thereby eliminating the need for high-power digital filtering
Solution Approach 2:
The patent introduces a mechanical intermediary component (the plug/blocking member) between the wind source and the microphone. This plug acts as a mediator that selectively blocks harmful wind noise while allowing desired acoustic signals to pass through the sound channel to the transducer
2Object-affected harmful factors
If mechanical protection from wind is provided, then wind noise reduction is achieved, but device size increases
Solution Approach 1:
The patent nests the moveable blocking member within the existing sound channel structure of the microphone assembly. The plug is positioned inside the sealed cavity and sound channel, utilizing the existing device volume rather than adding external protection components, thus reducing wind noise without increasing overall device size
Solution Approach 2:
The patent employs a dynamically adjustable blocking member that can move between different positions within the sound channel. This dynamic mechanism allows the system to adapt wind noise protection levels as needed while maintaining a compact form factor, rather than requiring fixed mechanical protection that would increase device volume
3Ease of manufacture
If the mechanical design of sound channels is fixed, then manufacturing simplicity is maintained, but adaptability to different acoustic environments is lost
Solution Approach 1:
The patent maintains a fixed, simple mechanical sound channel structure for ease of manufacture, but adds a dynamically controllable blocking member that can adjust the acoustic characteristics. This allows the system to adapt to different acoustic environments (windy conditions, quiet environments, different frequency responses) without complicating the base mechanical design
Solution Approach 2:
The patent enables adaptability by allowing changes in acoustic parameters (flow resistance, sound pressure levels, frequency response) through the movement of the blocking member within the fixed sound channel. The mechanical structure remains simple and manufacturable, while the adjustable plug provides versatility for different acoustic conditions
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 solution effectively reduces wind noise by dynamically adjusting the acoustic properties of the transducer, improving audio capture quality in portable devices without the need for extensive digital signal processing.
Implementation Method 1
a mechanical acoustic filter configured to be electrically controllable to change the acoustic properties of the transducer, wherein the mechanical acoustic filter comprises at least one filter hole
Implementation Method 2
at least one moveable blocking member configured to be electrically controllable, wherein the at least one blocking member is configured to selectively seal the at least one filter hole
Data Source
Figure 1
Figure 2a~2b
Figure 3
AI summary
An acoustic transducer comprising: a mechanical acoustic filter configured to be electrically controllable to change the acoustic properties of the transducer.