Metamaterial Wall Labyrinth for Broadband Sound Attenuation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional sound-absorbing walls struggle to uniformly attenuate low-frequency sounds, leading to frequency-dependent attenuation, and existing solutions like bass traps require significant space and are costly, while high-frequency attenuation methods are limited to specific applications.
Innovation Solution
A metamaterial wall with a sub-wavelength labyrinth structure that creates a closed air space with open-ended labyrinth passages, allowing for broadband sound absorption across the entire audible frequency range (20 Hz - 20 kHz) by leveraging complex geometric properties to achieve uniform damping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional sound-absorbing materials are used, then high frequency attenuation is achieved (A > 0.9), but low frequency attenuation is insufficient and highly frequency-dependent
Solution Approach 1:
The wall is segmented into multiple labyrinth passages with different path lengths, creating a distribution of resonant frequencies. Each passage segment contributes to attenuating specific frequency ranges, collectively achieving broadband attenuation from 20 Hz to 20 kHz
Solution Approach 2:
The sound absorption mechanism transitions from surface-level material properties to a three-dimensional labyrinthine structure. The complex spatial arrangement of passages creates acoustic paths that extend deep into the wall structure, enabling low-frequency attenuation without requiring the wall thickness to be a significant fraction of the wavelength
2Object-affected harmful factors
If bass traps with large spaces are used to dampen low frequencies, then low frequency attenuation is improved, but usable space is reduced and construction cost increases
Solution Approach 1:
The labyrinth passages are nested within the wall structure itself, with passages arranged in multiple levels and corridors that fold back on themselves. This nesting allows the acoustic absorption volume to be contained within the wall thickness without encroaching on usable interior space
Solution Approach 2:
The effective acoustic path length is extended through the labyrinth geometry while maintaining a compact physical footprint. By winding passages through the wall thickness and creating multiple reflection paths, the acoustic length becomes much greater than the wall thickness, achieving bass trap performance in a space-efficient manner
3Adaptability or versatility
If complex metamaterial structures are used to achieve broadband attenuation, then frequency-independent attenuation is improved, but device complexity increases
Solution Approach 1:
The wall incorporates a porous labyrinth structure where air-filled passages are distributed throughout the wall matrix. This porous arrangement allows sound waves to penetrate and interact with multiple passage configurations, achieving broadband attenuation through geometric complexity rather than material complexity
Solution Approach 2:
The wall functions as a composite structure combining solid wall material with air-filled labyrinth passages. The interaction between the solid matrix and air passages creates the acoustic metamaterial effect, where the geometric configuration of passages provides the frequency-independent attenuation without requiring complex or expensive materials
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 metamaterial wall achieves consistent sound attenuation of 50 dB - 70 dB across the frequency spectrum, reducing frequency dependence and maintaining a conventional wall size and cost-effectiveness, without the need for extensive space or complex construction.
Implementation Method 1
The labyrinth has eigenvalues ranging from this lowest eigenvalue in the bass range to the upper audible limit of 20 kHz and beyond. Each eigenvalue of the labyrinth space leads to a resonance of the sound within the wall
Implementation Method 2
Every frequency that resonates in the wall is attenuated in the wall, so that the sound energy of this frequency only emerges from the front and back of the wall in a very strongly attenuated form
Implementation Method 3
The plate prepared in this way dampens sound by swirling the speed of sound at the holes, with the turbulent damping converting the sound into thermal energy
Implementation Method 4
The three main materials used are bitumen, sandwich structures and nanofilaments. All of the processes occurring here that lead to internal damping have not yet been fully researched
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention is a wall for the massive, low-frequency and broadband sound attenuation of incident sound over a surface. It is used in the areas of sound absorption in and between rooms, soundproofing in outdoor areas, and room acoustics. The invention utilizes the principle of acoustic metamaterials. These are characterized by geometries consisting of individual elements whose lengths and sizes lie in the sub-wavelength range of the incident sound wave, thereby achieving massive, low-frequency, and broadband sound attenuation. For this purpose, cavities in the wall are used as labyrinthine structures, the labyrinthine passages of which are so complexly arranged that one passage end is open to several other passage ends. The labyrinthine passages are also joined together in such a way that the entire labyrinth forms a single air space (see drawing 1). Here, the building material plays no acoustic role and can therefore be chosen arbitrarily.