การฟัง TOEFL

🎧 บทถอดเสียง

Listen to part of a lecture in a biology class. The professor is discussing animal communication. Professor: Today we're going to talk about a fascinating aspect of animal behavior: communication. While we often think of communication as verbal, many animals rely on visual signals. Take the peacock, for example. Its elaborate tail is not just for show—it signals genetic fitness to potential mates. Similarly, the bright colors of poison dart frogs warn predators of their toxicity. But visual signals have limitations. They require light and a clear line of sight. That's why some animals, like elephants, use infrasound—low-frequency sounds below human hearing—to communicate over long distances through dense forests. These sounds can travel for kilometers without being blocked. Meanwhile, in the ocean, dolphins use echolocation, emitting high-frequency clicks that bounce off objects, helping them navigate and hunt in murky waters. Each mode of communication is an adaptation to the animal's specific environment and social needs. So, when we study animal communication, we must consider the ecological context—what works in one habitat may be useless in another.