Whales are social animals, and they use a series of sophisticated pitched moans and calls to communicate with one another. Each type of whale has its own frequency band within which all its communication takes place.
The solitary whale in this story has a high pitched cry, which is beyond the frequency that other whales can hear or respond to. He is known as the 52 Hz Whale, because that's the key that he sings in. Scientists have tracked his lonely progress for 25 years. They hear him every year as he swims through the Pacific Ocean in California. Always alone. Other whales can't hear him. And yet, he continues to sing.
The theory is that he is either the last whale of his kind, or a hybrid whale. I think his plight is one of the saddest stories I've heard. Not just because social animals deserve friendship, but because he reminds me that there are many people in this world who spend their entire lives in solitude.