A review published in Virtual and Physical Prototyping explores the growing field of additively manufactured acoustic metamaterials (ACA-Meta), highlighting how 3D printing technologies enable novel designs for effective sound absorption across diverse applications. Authored by researchers from Khalifa University and Dassault Aviation, the paper classifies acoustic metamaterials into perforated, slotted, cellular, and hybrid types and investigates how additive manufacturing enhances their performance.
Expanding acoustic control with 3D printing
Additive manufacturing offers unique benefits for acoustic metamaterials, enabling precise control over geometry, material distribution, and internal architecture. This level of control allows researchers and engineers to tailor acoustic behavior at specific frequency ranges, while simultaneously optimizing for weight, mechanical strength, and structural complexity.
Traditional sound-absorbing materials, such as porous foams or fibrous panels, are often constrained by fixed properties and limited adaptability. In contrast, 3D printing allows designers to create resonant structures and internal cavities with sub-wavelength precision, an essential factor in manipulating how sound waves interact with matter.
The review outlines how techniques such as Stereolithography (SLA), Selective Laser Melting (SLM), Fused Deposition Modeling (FDM), and Digital Light Processing (DLP) are being employed to fabricate a new generation of acoustic absorbers. These processes enable the construction of intricate geometries previously unattainable with conventional manufacturing, and allow for the fine-tuning of key parameters such as pore size, wall thickness, infill density, and material gradients. In doing so, additive manufacturing not only improves absorption efficiency but also broadens the usable frequency range of these metamaterials, making them more adaptable to specific environments and industrial requirements.
The paper categorizes these acoustic metamaterials into four structural families, each with distinctive mechanisms for managing sound waves. Perforated metamaterials absorb mid- to high-frequency noise by dissipating energy through arrays of micro-holes, often backed by air cavities to enhance low-frequency performance. Slotted designs employ labyrinthine or coiled channels to extend the acoustic path length, enabling effective attenuation at low frequencies within a compact footprint. Cellular structures, including periodic honeycombs, gyroids, and stochastic foams, are engineered to exhibit broadband performance through controlled porosity and internal resonance. Lastly, hybrid designs combine multiple features, such as perforated faces with embedded coiled cavities or layered cellular cores, to achieve tunable, wideband absorption across multiple acoustic regimes.
These classifications are not merely theoretical; each has been demonstrated through experimental validation, with performance metrics such as sound absorption coefficient (SAC) measured using impedance tubes and reverberation chambers. The paper emphasizes that even minor design modifications, like altering the angle of perforations or grading cell density, can have significant effects on absorption performance, reinforcing the value of additive manufacturing as both a prototyping and production tool in acoustic engineering.
Simulation and experimental validation
To quantify acoustic absorption, the study reviews both analytical models and experimental methods. Key parameters include the sound absorption coefficient (SAC), surface porosity, and sample orientation. Validation techniques such as impedance tube and reverberation room testing show that additively manufactured metamaterials can achieve or exceed the performance of traditional absorbers.
The review also identifies future directions, including volumetric 3D printing, multi-material printing, and 4D printing using smart materials for tunable acoustic responses. These approaches promise scalable, reconfigurable absorbers that can adapt to environmental changes or user-defined inputs.
Reshaping acoustic metamaterials
Interest in the acoustic capabilities of 3D printing has grown significantly in recent years. In 2019, researchers at the University of Sussex demonstrated a 3D printed metamaterial capable of directing sound to a specific location without the use of headphones, an early example of how additive manufacturing could redefine personal audio delivery. More recently, the University of Strathclyde received £500,000 in funding to develop miniaturized acoustic systems using 3D printing, aiming to advance compact and high-performance devices for sensing and communication.
Consumer audio brands have also embraced the technology; Campfire Audio, for instance, leveraged additive manufacturing to create earphones internal structure for their Supermoon series, optimizing both sound performance and fit. On a more experimental front, researchers have begun using sound itself as a medium for fabrication, as seen in a recent study on holographic Direct Sound Printing (DSP), which manipulates ultrasonic fields to solidify resin.
Together, these developments underscore the growing convergence of 3D printing and acoustic innovation, a convergence that the reviewed paper situates within the emerging domain of engineered sound-absorbing metamaterials.
Read the full article in Virtual and Physical Prototyping
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Feature image shows ACA-Meta fabricated by various additive manufactured techniques.
