Sound waves are produced by movement. Animals have evolved organs to detect those sound waves in the air or water to perceive movements in their environment. This can be used to find prey, predators, and mates. These are some of the animals that have mastered the sense of hearing. Frogs - Amphibians were the earliest species to develop an ear for hearing vibrations above the water. Their ear’s functionality is remarkably similar to a human’s eardrum. Frogs developed a tympanum to be able to hear other frogs mating calls. A larger tympanum signifies a big healthy male, and he has an advantage of mating with more females. Owls - Most birds of prey rely almost entirely on their vision to hunt. They, after all, have the best eyes in the world. The only weakness in their eyesight is that it requires a lot of light. These birds can’t hunt at night. Owls are the only exception; they’re more effective at night than during the day. That’s s because they use their sense of hearing. Their asymmetrical ears give them great directional hearing. Their parabolic face draws sound waves into their ears. Their wings have evolved to be completely silent in flight, so they don’t interfere when they’re looking for prey. Whales - There are two big groups of whales. They have very different social behaviours and communicate in different ways, and because of that, they have evolved different kinds of hearing. Baleen whales such as blue whales and are not very social. They spend most of their time by themselves and only get together to mate. To call each other, baleen whales emit low frequency calls that can travel vast distances in the water. Their ears are well adapted to hear very low frequency noises. Toothed whales, however, are extremely social. Orcas and porpoises communicate using very high-pitched noises and can echolocate. Giraffes - Giraffes live the vast savannahs of Africa. For a long time they were thought to be very quiet animals. But more recent research has shown that they vocalize a lot, but they have evolved to vocalize in very low frequencies. This is advantageous for them because low-frequency calls can travel further, and also they might be low enough that they can hear it but their predators can’t. To do that, they perform all kinds of interesting neck movements, to get lots of air through their throat and short intervals. For some young males, which end up leaving their home tower when they’re ready to mate, this is the best way to find mates. Cats and Rodents - Cats and rats have been tied up in an evolutionary arms race when it comes to hearing. Not only can both of them hear in the same range as humans, but they have the ability to pick up much higher frequencies in the ultrasonic range.

Part of the Animal Senses series. Transcript available under Additional info tag. Also available in Streaming.