Acoustically Resistive Membrane Assembly with Support Structure
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Solution Overview
Problem
There is a need for improved acoustic membranes that effectively manage sound propagation while preventing water and contaminant ingress, with existing solutions lacking in terms of airflow resistance, stiffness, acoustic impedance, and transmission loss consistency across a wide frequency range.
Innovation Solution
A predominantly resistive supported acoustic membrane assembly comprising a polymer membrane with a support structure, where the assembly has specific airflow resistance, stiffness, and acoustic impedance characteristics, and a transmission loss that remains consistent across a frequency range of 50 to 20,000 Hz, achieved through the use of materials like expanded polytetrafluoroethylene (ePTFE) and various support structures such as layers of fiberglass or metal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polymer membrane is used to allow sound propagation and prevent contaminant ingress, then acoustic permeability and contamination protection are improved, but airflow resistance and structural stability deteriorate
Solution Approach 1:
The patent combines a polymer membrane with a support structure (such as a porous substrate or frame) to create a composite assembly. The polymer membrane provides contamination protection and acoustic permeability, while the support structure adds structural stability and prevents membrane collapse, resolving the contradiction between reliability and strength
Solution Approach 2:
The patent employs porous materials for both the polymer membrane and support structure, allowing sound waves to propagate through the interconnected pores while maintaining structural integrity. The porous architecture enables acoustic permeability without compromising structural stability, as the rigid pore walls provide mechanical support
2Use of energy by moving object
If the polymer membrane thickness is reduced to improve acoustic transparency, then sound transmission is improved, but mechanical strength and water resistance deteriorate
Solution Approach 1:
The patent uses a composite structure where a thin polymer membrane (providing acoustic transparency) is bonded to a thicker support structure (providing mechanical strength). This composite approach allows the membrane to be sufficiently thin for acoustic performance while the support structure compensates for the reduced mechanical strength
Solution Approach 2:
The patent employs thin film technology to create a polymer membrane that is thin enough for acoustic transparency but is reinforced by the support structure to maintain mechanical strength. The thin film acts as an acoustic window while the support structure provides the necessary mechanical robustness
3Strength
If the assembly stiffness is increased to improve structural stability, then structural integrity is improved, but acoustic impedance control and sound transmission deteriorate
Solution Approach 1:
The patent uses porous materials with carefully controlled pore size, shape, and distribution to achieve the desired balance. The porous structure provides structural integrity through the rigid pore walls while the interconnected pores allow sound wave propagation with controlled impedance, preventing the stiffness from completely blocking acoustic transmission
Solution Approach 2:
The patent adjusts key parameters such as pore size, porosity, and material density to optimize the balance between structural integrity and acoustic impedance control. By carefully tuning these parameters, the assembly achieves sufficient stiffness for structural stability while maintaining appropriate acoustic transmission characteristics
4Reliability
If the airflow resistance is increased to improve sound filtration, then contaminant blocking is improved, but sound propagation and acoustic performance deteriorate
Solution Approach 1:
The patent employs porous materials with optimized pore architecture where the pore walls block contaminants while the interconnected pore network allows sound waves to propagate. The porous structure provides filtration through physical barrier mechanisms while maintaining acoustic transmission through the continuous pore pathways
Solution Approach 2:
The patent segments the structure into multiple layers with different pore sizes and functions. The outer layers provide contaminant blocking with smaller pores, while inner layers maintain sound propagation with larger pores, creating a segmented filtration system that preserves acoustic performance
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 assembly provides consistent sound transmission loss and resistance to water ingress, maintaining performance across a broad frequency range and offering improved acoustic performance in devices like speakers and receivers.
Implementation Method 1
Acoustic membrane assemblies can allow sound to propagate through and past a membrane
Implementation Method 2
the assembly has a water entry pressure ('WEP') ranging from 10 psi to 350 psi measured in accordance with the Capillary Piston Test ('CPT')
Implementation Method 3
a predominantly resistive supported acoustic membrane assembly that comprises a polymer membrane and at least one support structure
Implementation Method 4
the assembly has an acoustic impedance with a phase angle of +45 degrees to −45 degrees over a frequency range of 50 to 20,000 Hz
Data Source
AI summary
Water impermeable, air permeable membrane assemblies are described herein. In some embodiments, the assemblies include a polymer membrane and at least one support structure. Certain assemblies are configured to provide an acoustic impedance having phase angle of +45 degrees to −45 over a frequency range of 50 to 20,000 Hz.