All animals can use ultrasound and infrasound to communicate.

Some animals use sounds to tell each other about possible threats.

Scientists continue to discover new ways that animals communicate.

Body language is as important to elephant communication as sound is.

"Their ears open up wide and appear to hear distinct sounds, and yet the humans observing the scene nearby hear nothing." ("Incredible Animal Ears")

"These scientists concluded that the low sounds were actually warning sounds from another herd." ("Incredible Animal Ears")

"Sound travels in waves, and its pitch, or frequency, is measured in a unit that scientists call hertz." ("Animal Sounds")

"Elephants can communicate with other elephants up to ten miles away using a very low infrasound that the human ear cannot hear." ("Animal Sounds")

"Rats giggle at the ultrasound levels, and squirrels warn one another of danger by making high-pitched noises." ("Animal Sounds")

Humans can hear sounds that are between 20 and 20,000 hertz.

Animals communicate with each other using sounds, many of which people cannot hear.

Some animals communicate with high-pitched sounds called ultrasound; other animals use low-pitched sounds.

Elephants use different sounds for different situations, such as signaling their location or a need for help.

"Actually, the elephants are hearing a sound, but it has a pitch so low that humans can't detect it." ("Incredible Animal Ears")

"Scientists continue to study the sounds that elephants make, and it's no easy task." ("Incredible Animal Ears")

"So far, they have discovered 70 different sounds that they use for different situations." ("Incredible Animal Ears")

"Bees dance or emit smells to communicate with one another." ("Animal Sounds")

"Ye, one of the most important ways animals communicate is by sound." ("Animal Sounds")