An elephant’s trump is heard by all, but a new study has found that the animal can communicate at such low frequencies which are not audible to the human ears.

Researchers led by Matt Anderson of San Diego Zoo’s Institute for Conservation Research studied the “secret language” of elephants.

They monitored the animal’s growls that cannot be heard by human ears. These growls are only partly audible as almost two-thirds of these calls are at frequencies that are too low to be picked up by our hearing.

To learn more about the inaudible part of the growl, the team attached a microphone sensitive to these low frequencies and a GPS tracking system to eight of the zoo’s female elephants.

They then correlated the noises the animals were making with what they were doing and were able to learn that pregnant females use this low frequency communication to announce to the rest of their herd that they are about to give birth.

“We’re excited to learn of the hierarchy within the female herd and how they interact and intercede with one another,” Anderson was quoted as saying by the BBC.

“We’ve seen that after their long gestation of over two years, in the last 12 days we see a manipulation of the low part of the growl, the low part that we can’t hear.” Anderson added.

“This we believe is to announce to the rest of the herd that the baby is imminent,” Anderson said adding this warns others to look out for predators.

The team are further analysing the data to learn more about this secret elephant language.

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