infrasound

infra- +‎ sound

infrasound (countable and uncountable, plural infrasounds)

1. (physics) Sound waves having a frequency below the human audible range (below about 20 Hz).
   • 2008, BioWare, Mass Effect, Redwood City: Electronic Arts, →ISBN, OCLC 246633669, PC, scene: Elcor Codex entry:

     Elcor speech is ponderous and monotone. Among themselves, scent, slight movements, and subvocalized infrasound convey shades of meaning that make a human smile seem as subtle as a fireworks display. Since their subtlety can lead to misunderstandings with other species, the elcor often go out of their way to clarify when they are being sarcastic, amused, or angry.

• ultrasound

• infrasonic, infrasonics