Beyond phase grating diffusers using locally-resonant metamaterials

Noé Jiménez, Trevor Cox, Jean Philippe Groby, Vicente Romero García
2019 Proceedings of the ICA congress  
We present sound diffusers based on locally resonant metamaterials that are one order magnitude thinner than the classical designs based on phase gratings. Using a set of waveguides loaded by an array of optimized Helmholtz resonators, we induce strong dispersive propagation inside the material. Doing this, waves in the low-frequency regime are dramatically slowed down and, because of this, a deep-subwavelength resonance is produced. In addition, this design allows an accurate tuning of the
more » ... e tuning of the thermoviscous loses. In this way, the reflection coefficient can be spatially tuned in both phase and magnitude, and we are able to mimic the classical QRD, PRD or Binary/Ternary sound diffusers. Beyond these designs, we also propose an optimized panel showing efficient and broadband sound diffusion ranging from 250 Hz to 2 kHz using only 3 cm thickness, i.e., 46 times thinner than the wavelength at the lowest working frequency.
doi:10.18154/rwth-conv-239375 fatcat:m4xxjt2lrzfuja5tjkno6of54q