This video is called Blue Whale Song. Deep Sounds from a Blue Whale.
From Science Centric:
The sound level of songs blue whales sing across the vast expanses of the ocean to attract potential mates has been steadily creeping downward for the past few decades, and a scientist at Scripps Institution of Oceanography at UC San Diego and his colleagues believe the trend may be good news for the population of the endangered marine mammal.
This video says about itself
Blue whales align the pitch of their songs with extreme accuracy, study finds: Blue whales are able to synchronize: here.
Anti-whaling conservationists say they are again intent on disrupting Japanese whalers in the Southern Ocean and are concerned humpbacks may be included in the hunt this season, for the first time: here.