Dolphins communication is a bit different from a hippos way of talking. Dolphins do not have vocal chords so they communicate with a system of clicks, and other sounds. The average dolphin call ranges from 0.2 to 24 kHz. A kilohertz is the way that frequencies of sound are measured. A hippo’s call ranges from 14 to 24 kHz. These animals use lower frequency calls underwater because low frequency sounds travel further. A hippo’s and a dolphin’s call are fairly close in frequencies.