Lesson Plan - Get It!
The Earth is full of thousands of different species of animals and creatures. Did you know that some of these creatures, including those pictured, are capable of hearing sounds that humans cannot?
In the previous Related Lessons in this All About Sound series, found in the right-hand sidebar, you learned how humans are able to hear.
Do you remember how humans hear? Explain the answer to your teacher or parent.
Humans hear when sound waves travel into the ear, causing the ear drum to vibrate. These vibrations, created by the eardrum, move to the inner ear, where there are tiny hairs. The vibrations cause these tiny hairs to move, sending signals to the brain. The brain interprets these signals as sound.
Not all animals make and hear sounds the same way humans do. In this lesson, you will discover how some animals communicate and interpret sounds.
To start, read the article Why Can Some Animals Hear Noises That Others Cannot? (Whalerock Digital Media, LLC.). After you finish reading the article, discuss the following questions with a teacher or parent:
- What frequency range can humans hear best?
- Why can some animals hear sounds that humans cannot?
- What are three animals that can hear things humans cannot?
Humans hear best at a frequency between 1,000 to 5,000 Hz, although most humans can hear up to 20,000 Hz. Some animals, on the other hand, can hear frequencies of over 100,000 Hz! Different features allow these animals to hear high-pitched sounds. Some animals that can hear sounds differently than humans include bats, dolphins, snakes, and spiders.
Bats and dolphins are some of nature's best listeners! Bats can hear frequencies up to 110,000 Hz, and dolphins are known to hear frequencies of 120,000 Hz.
Bats and dolphins use echolocation. Using echolocation, they produce high-pitched sounds to send out sound waves. These sound waves bounce off objects and return to the animal that created the sound, like a boomerang. When the sound wave returns to the animal, it gives it an idea of whether there are objects around them and how far away those objects are. This allows them to see and interpret their environment.
How would echolocation be useful to a bat or dolphin? Discuss your answer with a teacher or parent.
Bats hunt at night and dolphins live in the depths of the ocean, where it can be dark. Echolocation helps bats and dolphins see their surroundings when it is dark. To learn more about how bats use echolocation, watch Bats Using Echolocation Around Humans? (Brave Wilderness):
Bats and dolphins can hear high-pitched sounds, but snakes can only hear low-pitched sounds. This is because snakes do not have an ear or opening on the side of their head to let sound in. This does not prevent them from taking in vibrations created by sound, though. The snake's skin, muscles, and bones are able to feel vibrations and carry the vibrations to the snake's inner ear, a part inside its head that interprets vibrations as sound. You can learn more about how snakes hear by reading Snakes hear through their jaws (Eric Bland, ABC). What is the connection between a snake's jaw and its hearing? Explain the answer to your teacher or parent.
Have you ever thought about the way spiders can hear? Did you even know that spiders can hear? Spiders hear using tiny hairs on their legs. These tiny hairs sense vibrations created by sounds. These hairs are so sensitive that they can even hear air moving when people and objects move about. Scientists are continually researching and studying the way spiders hear. Read the recent study, A Spider Across The Room Can 'Hear' You, Study Finds (Merrit Kennedy, NPR), to find out more. What does this study reveal about a spider's ability to hear? Tell your teacher or parent.
Bats, dolphins, snakes, and spiders are just a few animals that hear and create sounds differently than humans. Continue on to the Got It? section to compare and contrast what you have learned.