infrasonic

Elephants can speak to each other using infrasonic rumbles — sounds that humans are incapable of hearing — that travel long distances and warn other nearby elephants of potential danger.

One of the most striking features of the Nord Stream events is its long-lasting seismic and infrasonic signals, the researchers found.

Etna's explosions generate "infrasonic waves" that the human ear does not pick up because of their low sound frequency, but the glass in the windows does.

The study offers few clues about how terns might do this, but other research suggests some migrating birds detect infrasonic weather signals or observe changing clouds.

After digging through decades of literature in the field, Jauchem concluded that infrasonic weapons are impractical.