MEMS Slit Membrane Venting for Wearable Audio Occlusion
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Solution Overview
Problem
Wearable sound devices experience an occlusion effect due to the sealed ear canal, leading to loud perceived sound pressure and reduced sound pressure level in lower frequencies, which is difficult to address without compromising device size or durability.
Innovation Solution
A MEMS device with a film structure and slit mechanism that temporarily forms a vent between the ear canal and ambient, allowing pressure equalization while maintaining sound quality and device integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a fixed vent is configured to form an airflow channel between the ear canal and ambient, then the occlusion effect is suppressed, but the sound pressure level in lower frequency drops significantly
Solution Approach 1:
The patent replaces the fixed vent with a dynamic membrane structure that can change its state between blocked and open positions. The membrane is actuated by a driving mechanism (such as a piezoelectric actuator or electromagnetic driver) to dynamically adjust the airflow channel opening, allowing the system to adapt between suppressing occlusion effect and maintaining sound pressure level according to operational conditions.
Solution Approach 2:
The patent changes the parameter of the airflow channel from a fixed geometric opening to a variable opening controlled by membrane displacement. By controlling the displacement amount and timing of the membrane, the system can modulate the degree of venting to optimize both occlusion effect suppression and acoustic performance across different frequencies.
2Quantity of substance
If a stronger speaker driver is used to compensate for the loss of sound pressure level, then the sound pressure level is maintained, but the device size and weight increase
Solution Approach 1:
The patent introduces the membrane as an intermediary element between the sealed ear canal and the ambient environment. This membrane-mediated airflow channel provides a controlled path for pressure equalization, allowing the use of smaller, lighter speaker drivers while still maintaining adequate sound pressure level by optimizing the balance between acoustic sealing and pressure release.
3Object-affected harmful factors
If a larger fixed vent is used to suppress the occlusion effect, then the occlusion effect is reduced, but water and dust protection becomes more difficult
Solution Approach 1:
The patent employs a dynamic membrane that can transition between closed and open states, allowing the system to provide water and dust protection when the membrane is in the closed position while still enabling occlusion effect suppression when opened. This dynamic control allows the opening to be smaller than a fixed vent would require, thereby maintaining IP protection ratings.
4Quantity of substance
If the ear canal is completely sealed to maintain sound quality, then the sound pressure level is maintained, but the occlusion effect becomes stronger
Solution Approach 1:
The patent extracts the pressure equalization function from the acoustic sealing system by introducing a separate membrane-controlled airflow channel. This allows the main ear canal seal to remain intact for maintaining sound pressure level and acoustic quality, while the extracted venting function through the membrane handles pressure relief to suppress the occlusion effect.
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 device effectively suppresses occlusion effects by maintaining sound pressure levels across frequencies without increasing device size or weight, while ensuring durability and acoustic performance.
Implementation Method 1
the film structure is configured to be actuated to form a vent temporarily, and the vent is formed because of the slit. The ear canal and the ambient are to be connected via the vent temporarily opened
Data Source
AI summary
A manufacturing method for a device includes: providing a wafer including a first layer and a second layer; forming and patterning an actuating material formed on the wafer; patterning the first layer of the wafer to form a trench line; and removing a first part of the second layer. The first layer forms a film structure including a membrane. A slit is formed within and penetrates through the membrane because of the trench line. The film structure is actuated to form a vent temporarily because of the slit. An ear canal and an ambient of a wearable sound device are to be connected via the vent temporarily opened. The slit divides the membrane into a first membrane portion and a second membrane portion. A difference between the displacements of these two membrane portions is larger than a thickness of the membrane when the vent is formed.