Choose all the sentences that are written in active voice. like humans, who use words and gestures to communicate bottlenose dolphins use many sounds and body movements to convey information to one another. during one study, researchers in hawaii listened as a mother dolphin and her baby—swimming in separate tanks—chatted to each other through a special audio device. the sounds of a mother dolphin reaching out to her baby were heard by scientists who had separated the mother and child into two different tanks. whistle-like noises are produced through vibrations in the tissue of the dolphin's nasal cavities. in addition to sounds, bottlenose dolphins communicate through body language and touch.