Transparent Acoustic Panel With Scatterers for Low-Frequency Isolation
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Solution Overview
Problem
Conventional porous sound absorbing materials are inefficient for low-frequency noise reduction due to their high impedance nature and the 'mass-law' limitation, which makes it difficult to achieve high sound transmission loss (STL) while maintaining lightweight materials.
Innovation Solution
A sound absorbing structure comprising an array of acoustic scatterers attached to a transparent panel, which can be made of materials like glass or polymethyl methacrylate, allowing for high STL beyond the 'mass-law' limitations by achieving total acoustic absorption even at a thickness of 1/16 of the wavelength, with the acoustic scatterers behaving like monopole sources to cancel out sound waves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If material mass is increased to achieve high sound transmission loss, then sound isolation performance is improved, but material weight increases due to mass-law limitation
Solution Approach 1:
The patent changes the acoustic parameters of the panel by attaching acoustic scatterers that resonate at specific frequencies. This resonance effect creates sound transmission loss without increasing panel mass, breaking the mass-law limitation by using acoustic impedance mismatch and resonance rather than mass alone.
Solution Approach 2:
The acoustic scatterers act as intermediary elements between the incident sound waves and the panel. These scatterers resonate and absorb sound energy, mediating the interaction between sound and panel to achieve high sound transmission loss without requiring heavy panel materials.
2Loss of energy
If high sound absorption is achieved through impedance matching, then sound absorption efficiency is improved, but sound transmission loss deteriorates due to high transmission
Solution Approach 1:
The patent applies local quality by creating regions of high acoustic impedance (the acoustic scatterers) distributed across the panel surface. These localized high-impedance regions absorb sound through resonance while the overall panel structure maintains sound transmission loss, resolving the contradiction between absorption efficiency and transmission loss.
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 structure effectively absorbs low-frequency noise across a wide range of frequencies, breaking the 'mass-law' near the resonant frequency of the acoustic scatterers, achieving higher STL than conventional methods without reflecting sound, thus providing superior sound isolation.
Implementation Method 1
The acoustic scatterer may include a resonating structure that achieves total acoustic absorption at a resonant frequency of the acoustic scatterer
Implementation Method 2
the acoustic scatterers behaving like monopole sources to cancel out sound waves
Data Source
AI summary
A sound absorbing structure includes a panel having a first side and a second side and at least one acoustic scatterer coupled to a first side of the panel. The panel may be at least partially transparent. The at least one acoustic scatterer has an opening and at least one channel. The at least one channel has a channel open end and a channel terminal end with the channel open end being in fluid communication with the opening. The panel may be utilized to separate an interior space from an exterior space.