I₁N₁F₄R₁A₁S₁O₁U₁N₁D₂S₁

15 points

INFRASOUNDS is validvalid

INFRASOUND, sound waves too low-pitched for humans to hear [n]

153,244 of 196,601 in NWL2023·also valid in CSW24

INFRASOUND, frequencies below the usual audible limit [n]

120,354 of 280,887 in CSW24·also valid in NWL2023