In response to a recorded humpback ‘contact’ call played into the sea via an underwater speaker, a humpback whale named Twain approached and circled the team’s boat, while responding in a conversational style to the whale ‘greeting signal.’ During the 20-minute exchange, Twain responded to each playback call and matched the interval variations between each signal.

CETI is such a cool project. I wonder how far they'll be able to get with it.