The ARE device uses scattering structures to split broadband white noise from a single source into an acoustic rainbow. The sound is mapped on a visible spectrum based on magnitude and frequency. (Image Credit: Science Advances)
Researchers from the Technical University of Denmark and Universidad Politécnica de Madrid developed an acoustic rainbow emitter (ARE) device. ARE captures broadband white-noise signals from an omnidirectional single source and disperses them to emit frequencies in multiple directions.
Although modern acoustic systems have sound-splitting capabilities in enclosed environments, they cannot achieve fully controlled, broadband auditory manipulation in open-field environments. So, the team addressed that limitation by using computational morphogenesis, a process employing structural optimization algorithms and finite element analysis to produce complex shapes.
Topology optimization, precise wave-based modeling, and existing fabrication methods like 3D printing have allowed researchers to design complex geometries capable of sound manipulation. With these tools, they managed to sequentially fine-tune the solid material’s shape to direct the emitted sound based on the desired pattern across various frequencies. Additionally, the Helmholtz equation simulated the way sound travels and scatters in the air around a reflective structure.
The team used the computational models’ data to produce a new solid object from a single material. Featuring scattering properties, the object captures sound frequencies from a point source, separating them into their spectral components to generate an acoustic rainbow. Additionally, the team developed a lambda splitter designed to capture sound frequencies and emit low and high-frequency sound waves in varying directions.
These devices use passive scattering, which involves shaping the sound via its interactions with the hard plastic surface without relying on electricity. The rainbow emitter and lambda splitter are representative of how passive structures control sound without using power-intensive resonance or active components.
According to the team, this study demonstrates how computational morphogenesis can accurately control how sound is emitted and received. This has the potential to provide insights for fields focused on wave sensing and control.
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