Abstract
Optical holograms can modulate light wavefronts to generate visible images. In the same way, acoustic images can also be synthesized by holograms, shaping the areas where mechanical waves present a high amplitude, and areas where the media is at rest. In this talk, we will present the recent advances of acoustic holograms and metamaterials to control the reflected field in room acoustics. First, we present an approach to reduce the thickness of traditional sound diffusers using metamaterials. By tuning the resonance and the local absorption of the structure, broadband and efficient sound diffusion can be produced using panels 20 times thinner than traditional designs. The potential of structured materials to control acoustic reflections can be enhanced by designing spiraling panels that reflect acoustic vortices. These kind of twisting waves present phase dislocations at its axis, and waves, as a whirlpool, interfere destructively at this location. In this way, the specular component vanish and the scattering coefficient reaches very high values. Finally, recent proposals based on far-field holograms are presented to design scattering patterns on demand for specific applications.
BibTeX citation
@inproceedings{JimenezSAA2021Diffusers,
author = {Noé Jiménez},
booktitle = {2o Simposio sobre Acústica Arquitectónica - SAA 2021. Online, 24 June},
editor = {Universidad Austral de Chile},
isbn = {ISSN: 0001-4966},
month = {06},
organization = {Universidad Austral de Chile},
publisher = {Instituto de Acústica, Facultad de Ciencias de la Ingeniería},
series = {Plenary / Keynote},
title = {Advanced control of sound reflections: from twisting to holograms and subwavelength resonances},
year = {2021}
}