We theoretically and experimentally propose two designs of broadband low-frequency
acoustic metasurface coiled absorbers (Sample I/Sample II) for the frequency ranges of 460
Hz–972 Hz and 232 Hz–494 Hz (larger than 1 octave), with absorption larger than 0.8
(average is 0.87), and having the ultra-thin thickness of 4.5 cm and 9 cm respectively (λ/17
for the lowest working frequency and λ/8 for the highest frequency). The designed supercell
consists of 16 different unit cells corresponding to 16 eigen frequencies for resonant …

We theoretically and experimentally propose two designs of broadband low-frequency
acoustic metasurface absorbers (Sample I/Sample II) for the frequency ranges of 458Hz~
968Hz and 231Hz~ 491Hz (larger than 1 octave), with absorption larger than 0.8, and
having the ultrathin thickness of 5.2 cm and 10.4 cm respectively (λ/15 for the lowest working
frequency and λ/7.5 for the highest frequency). The designed supercell consists of 16
different unit cells corresponding to 16 eigen frequencies for resonant absorptions. The …