What the study reports
The authors use a power-law density gradient instead of relying only on a thickness taper. Their model lowers the cut-on frequency to one-fifth of the conventional comparison. The tested device reports wave absorption across 25–1,200 Hz, with a threshold of 24.5 Hz. [1]
What this does not establish
These frequencies describe the paper’s device and test system. They are not a universal absorption range. Here, “acoustic black hole” refers to engineered flexural-wave behavior, rather than a gravitational phenomenon or proof of room-scale airborne sound absorption.
Our engineering reading
Density distribution provides another control variable for vibroacoustic design. Transfer to a new host requires its dimensions, coupling and loading to be evaluated.
Editorial interpretation; not an additional measured result.Deep-subwavelength ultra-low and ultra-broadband acoustic-black-hole metamaterials
Yanni Zhang et al. · Nature Communications · 13 December 2025
DOI: 10.1038/s41467-025-66172-2Source access: Publisher full text. Checked 3 October 2026.