Microphone Test Module with Noise Suppression
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Solution Overview
Problem
Existing microphone test methods fail to effectively suppress structure-borne noise, which can interfere with the accuracy of testing and calibration of MEMS microphones used in mobile devices, despite efforts to reduce airborne sound through vacuum environments.
Innovation Solution
A microphone test module and method that utilize an airtight outer chamber with a sound chamber connected via a structure-borne noise suppression mechanism, such as elastic or magnetic coupling, and a vacuum pump to create a pressure differential between the chambers, reducing both airborne and structure-borne noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a vacuum environment is used to reduce airborne sound, then airborne noise is reduced, but structure-borne noise interference remains and affects testing accuracy
Solution Approach 1:
The test module is divided into two independent chambers: an outer chamber that can be evacuated to reduce airborne noise, and an inner sound chamber that maintains acoustic isolation. This segmentation allows different noise suppression mechanisms to operate in different spatial zones, addressing both airborne and structure-borne noise separately.
Solution Approach 2:
A connection structure with suppressed structure-borne noise transmission acts as an intermediary between the outer and inner chambers. This intermediary element blocks the transmission path of structure-borne vibrations while still allowing the inner chamber to be acoustically isolated, preventing vibration transfer from the vacuum chamber walls to the test environment.
2Object-affected harmful factors
If the outer chamber is evacuated to lower pressure, then airborne sound transmission is reduced, but the complexity of the test module increases due to additional vacuum components
Solution Approach 1:
The modular chamber design segments the vacuum system from the test environment, confining vacuum components (pump, seals, pressure sensors) to the outer chamber while keeping the inner sound chamber simple and dedicated solely to acoustic testing. This reduces overall system complexity by localizing complex functions.
Solution Approach 2:
The inner sound chamber is nested within the outer vacuum chamber, creating a chamber-within-a-chamber configuration. This nesting allows the simpler inner chamber to benefit from the noise reduction of the outer vacuum chamber without requiring its own complex vacuum system, reducing total system complexity.
3Object-affected harmful factors
If structure-borne noise suppression is implemented through elastic or magnetic coupling, then vibration transmission is reduced, but the device complexity increases
Solution Approach 1:
The connection structure with suppressed structure-borne noise transmission serves as an intermediary element between the outer and inner chambers. It actively blocks vibration transmission paths while maintaining the structural integrity needed to support the inner chamber, reducing noise without requiring complex active control systems.
Solution Approach 2:
Magnetic coupling or elastic materials replace traditional rigid mechanical connections between chambers. This substitution eliminates direct vibration transmission paths while maintaining structural support, reducing structure-borne noise without requiring complex mechanical damping systems.
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 significantly reduces noise interference, enhancing the accuracy of microphone testing and calibration by effectively suppressing both airborne and structure-borne sounds, thereby improving the reliability of MEMS microphone testing.
Implementation Method 1
a space between the outer chamber and the sound chamber has a gas pressure being lower than an ambient air pressure
Implementation Method 2
the sound chamber is coupled to the outer chamber with a connection suppressing structure-borne noise between the outer chamber and the sound chamber
Implementation Method 3
the sound chamber is coupled to the outer chamber with a connection suppressing structure-borne noise between the outer chamber and the sound chamber
Data Source
AI summary
A test module for testing microphones comprises an outer chamber being airtight, and a sound chamber comprising an electrical test device for testing the microphones. The sound chamber is located within the outer chamber, and the sound chamber is coupled to the outer chamber with a connection suppressing structure-borne noise between the outer chamber and the sound chamber. A space between the outer chamber and the sound chamber has a gas pressure being lower than an ambient air pressure. A method of testing microphones comprises evacuating the space between the outer chamber and the sound chamber to having a lower gas pressure than an ambient air pressure, and testing the microphone.