3D-printed device splits white noise into an acoustic rainbow without power

Summary

The morphogenetical topology optimization method shapes the scattering inclusions, shown as gray material. When the ARE is excited by monopolar source emitting broad-band white noise, the radiated sound creates an acoustic rainbow. The source is positioned at the center of the emitter (illustrated using white light) and driven with equal power at all frequencies from 7,600 to 12,800 Hz. The experimentally measured acoustic output (far field) is mapped to the visible spectrum of light by its magnitude and frequency content in the full 360° surrounding the ARE. Credit: Science Advances (2025). DOI: 10.1126/sciadv.ads7497 In a study published in Science Advances, researchers from Technical University of Denmark and Universidad Politécnica de Madrid demonstrate a new device called an acoustic rainbow emitter (ARE) that takes in broadband white-noise signals from a point source that radiates sound equally in all directions and scatters it up so that different sound frequencies or pitches are emitted. Similar to how a prism splits white light into a rainbow, the ARE device steers each frequency in different directions, creating an acoustic rainbow. In nature, some animals—like humans, bats, and dolphins—have evolved intricate ears (pinnae) that can catch, shape and direct sound in amazing ways, helping them sense and navigate their surroundings. Despite ample natural inspiration, humans have struggled to design systems that can work on a wide range of frequencies. Unlike nature, which utilizes passive structures to shape sound, most artificial sound control systems require active devices or resonance-based systems. Animation of a rotating ARE driven by broad-band white-noise and the audio heard by an observer. The ARE (white) is shown rotating relative to an observer (red dot) with the far-field sound pressure mapped to the optical rainbow and the sound heard by the observer under white-noise excitation of the ARE played as audio. Credit: Science Advances (2025). DOI: 10....