Morphogenesis of sound creates acoustic rainbows

TL;DR

This paper introduces a computational approach to designing passive, energy-efficient acoustic structures that passively decompose sound into its spectral components, mimicking natural morphogenesis.

Contribution

It demonstrates the first synthesis of complex, passive, wavelength-sized scattering structures using computational morphogenesis, achieving high efficiency in sound decomposition.

Findings

Designed an acoustic rainbow structure with above unity efficiency.

Created an acoustic wavelength-splitter for sound decomposition.

Paves the way for advanced sound-field engineering applications.

Abstract

Sound is an essential sensing element for many organisms in nature, and multiple species have evolved organic structures that create complex acoustic scattering and dispersion phenomena to emit and perceive sound unambiguously. To date, it has not proven possible to design artificial scattering structures that rival the performance of those found in organic structures. Contrarily, most sound manipulation relies on active transduction in fluid media rather than relying on passive scattering principles, as are often found in nature. In this work, we utilize computational morphogenesis to synthesize complex energy-efficient wavelength-sized single-material scattering structures that passively decompose radiated sound into its spatio-spectral components. Specifically, we tailor an acoustic rainbow structure with "above unity" efficiency and an acoustic wavelength-splitter. Our work paves the way for a new frontier in sound-field engineering, with potential applications in transduction, bionics, energy harvesting, communications and sensing.