Elephants live out their long lives in an exceptionally complex social network of persistent relationships. Their communication system, or language, is similarly complex.Vision and olfaction (smell), in addition to sound, are important for elephant communication.
The video and spectrogram below show an intense greeting between two African forest elephant females, Kate and Tess.
Each rumble appears as a stack of crescent-shaped lines in the spectrogram. These are called 'harmonics' and they are exact multiples of the frequency at which the vocal folds ('cords') vibrate. At several places in this vocal exchange, the voices of the two elephants overlap. This is very typical of greetings like this.
The Elephant Listening Project is focused on acoustic communication because forest elephants are very difficult to observe visually everywhere except during their brief visits to forest clearings. However, all three species of elephant (Asian, African savannah and African forest) make calls with fundamental frequencies below the lower limit of human hearing (20 Hz), in the range called infrasound. These infrasonic calls can travel far through the environment.
We are only in the early stages of decoding this language - understanding the meaning of specific signals so that we can use these to study forest elephants and help in their conservation.