Xindi-Aquatic language

The Xindi-Aquatic language is the very complex language used by the Xindi-Aquatics. It consists of high or low pitch hums that are similar to those produced by Terran whales.

The language switches to SONAR when the past tense is used. 

Hoshi Sato said that she thought the Xindi-Insectoid language was difficult while trying to translate an Aquatic message. Commander Dolim heard the language his entire life, but it never came easily to him.