This dataset captures 66 published patent families between 2015 and mid-2026, filtered to acoustic metamaterial, metasurface and sonic crystal filings that also address band-gap, low-frequency absorption, sub-wavelength structure or ventilated barrier claims. That is a relatively small, tightly scoped field compared to broader acoustics categories. The true figure is somewhat higher because publication typically lags filing by around 18 months, so the most recent year is always undercounted at the time of any snapshot.

Filing is spread across a mix of Chinese and US universities and research institutes rather than concentrated in one or two dominant players, with China's patent office receiving more than half of all records in this dataset. Notably, the assignees who appear most often historically — including several Chinese and US universities — all show zero filings in the latest tracked year, a pattern worth verifying against pending applications rather than treating as a confirmed exit. A national lab, Sandia, holds one of the more heavily cited manufacturing-process families.

Nearly all records in this dataset classify under G10K, the acoustics and sound generation IPC subclass, with folded-beam phononic crystals, piezoelectric low-frequency broadband layouts and sub-wavelength local-resonance structures appearing repeatedly among the most-cited families. Crossover into radar/sonar, medical diagnosis, additive manufacturing and road or rail noise barriers exists but remains small, at 3 to 6 records each. That imbalance suggests the underlying acoustic theory is well-trodden while its application into adjacent industries is comparatively unclaimed.

The clearest gaps sit in application areas with only a handful of filings against a much larger acoustics-native base: ventilated sound-barrier geometries, underwater sub-wavelength resonators, and 3D-printed micro-resonator arrays combining additive manufacturing with tuned resonator design. These branches show real citation activity in the top-cited list but shallow overall filing density, meaning a well-drafted claim there faces less crowded prior art than a claim on core band-gap resonator geometry. Any white-space read should be paired with a fresh claim-by-claim check, since a thin count can also mean a niche nobody wants rather than one nobody has tried.

The 2025 peak of 15 families is the highest point in the tracked trend, up from a midpoint of 5 filings in 2022 and just 2 in 2017, showing genuine recent growth rather than early-stage noise. The apparent drop in 2026 is very likely a publication-lag effect rather than a real slowdown, since patent applications typically take about 18 months to publish and this dataset's cut-off is mid-2026. Readers should treat the 2026 figure as a floor, not a final count, and revisit the trend once a full year of filings has had time to publish.