Noise pollution has become a significant global problem in recent years. Unfortunately,
conventional acoustic materials cannot offer substantial improvements in noise reduction …

The coupling of waves between the piezoelectric generators, detectors, and propagating
media is challenging due to mismatch in the acoustic properties. The mismatch leads to the …

Within a time span of 15 years, acoustic metamaterials have emerged from academic
curiosity to become an active field driven by scientific discoveries and diverse application …

Acoustic metamaterials, structured to produce anomalous reflection and refraction indices
that are not found in conventional materials, are gaining prominence in engineering …

Acoustic metamaterials (AMs), which are materials composed of subwavelength periodic
artificial structures with specific designs, have drawn significant research attention. This is …

The causal nature of the acoustic response dictates an inequality that relates the two most
important aspects of sound absorption: the absorption spectrum and the sample thickness …

The recent advent of acoustic metamaterials has initiated a strong revival of interest on the
subject of sound absorption. The present review is based on the physics perspective as the …

In order to improve and broaden the sound absorption performance of porous materials with
low flow resistance, this study proposes the composite meta-porous structure embedded …

An impedance-matched surface has the property that an incident wave generates no
reflection. Here we demonstrate that by using a simple construction, an acoustically …

Negative refraction of elastic waves has been studied and experimentally demonstrated in
three-and two-dimensional phononic crystals, but Bragg scattering is impractical for low …