Case Studies
A. Migrating birds
They use naturally generated infrasound, from sources such as turbulent airflow over mountain ranges, as a navigational aid.
B. Elephants
Infrasound may also be used for long-distance communication in African elephants.
They can produce infrasound waves that travel through solid ground and are sensed by other herds using their feet, although they may be separated by hundreds of kilometres.
These calls range from 15-35Hz and can be as loud as 117dB, allowing communication for many kilometres, with a possible maximum range of around 10km.
These calls may be used to coordinate the movement of herds and allow male elephants to find mates.
They use infrasound - which can travel vast distances through the ground, air, and water - to carry on long-distance conversations.
Researchers have homed in on these "invisible" communications in just the last few decades, as sophisticated microphones and recording equipment allowed them to listen in.
Now, infrasound researchers wonder whether some animals can hear danger approaching. For instance, big storms such as hurricanes produce their own distinctive infrasonic signature.
Similarly, earthquakes can produce several distinct infrasound pulses that can travel thousands of miles and much faster than water.
Thus, tsunamis, also triggered by earthquakes, hit the shores only after infrasound.
C. Alligators
Alligator researchers are cracking the code that these huge reptiles use to signal their mates.
They have learned that alligators can produce an array of infrasonic signals by vibrating air inside special sound-producing sacs in their chins.