The sound is sharp, spare and strange, a burst of clicks cutting through seawater. For years, researchers treated those sperm whale signals mostly as timing patterns, measuring pauses and rhythms the way someone might study Morse code. But a new analysis suggests there is more going on inside those clicks than timing alone. Some of the animals’ codas, the short click sequences sperm whales use to communicate, appear to contain something like vowel structure. Not human language, and not proof that whales are “talking” in the way people do, but a communication system with features that look surprisingly close to human phonology. That is what makes the new work stand out. It does not claim to have decoded whale meaning. Instead, it points to structure, and a lot of it. Researchers working with Project CETI and the University of California, Berkeley analyzed thousands of sperm whale recordings and found that these codas fall into two distinct acoustic categories. The team describes them as a-vowels and i-vowels because they resemble broad differences seen in human vowel …