In Questions about Hearing, Ear Shape, and How Whales Hear, students use scientific inquiry to learn about hearing. Inquiry involves asking a simple question, doing an investigation, answering the question, and presenting the results to others. Note that these three lessons should be presented in the order listed above.
In this lesson, students discover that aquatic mammals like whales have ear structures that are different from those of humans and other land animals, yet they are perfectly suited to life underwater. They begin by watching a video that describes how a scientist unraveled the mystery of whale hearing. Then they conduct an experiment that demonstrates that hearing is the result of vibrations being transmitted to the inner ear, and that this can be done with or without outer ears and ear canals to funnel sound.
- Discover how researchers use scientific inquiry to learn how whales hear
- Label the parts of the whale ear
- Model how whales and similar aquatic mammals hear
- Understand that the ability to hear is due to one's ability to detect vibrations
Grade Level: 3-5
- Two 45-minute blocks
- Guess How Whales Hear! QuickTime Video
- Whale and Human Ears PDF Document
- Sea life is troubled by noise PDF Document
- Using Scientific Inquiry to Explore Whale Hearing PDF Document
- How do whales hear? PDF Document
- Metal spoons (one for each pair of students)
- Dental floss (3 feet for each pair of students)
- Assortment of strings (such as yarn, kite string, twine, thread)
- Assorted metal and wooden spoons and forks
Before the Lesson
- Make copies of the handouts for students.
- Have students retrieve their copies of theWhale and Human Ears (PDF) diagram from the lessonQuestions about Hearing.
- Collect the materials needed for the experiment."
Sound waves travel not only through the air (gas) but through solids and liquids too. Because of this, animals that live underwater can hear just fine, although their ear structures are different from those of land animals.
1. Have students plug their ears with their fingers. Turn your back to them and talk quietly. Then have them unplug their ears, and ask them the following:
- Could you hear me talking?
- Think about what you know about hearing. What are you preventing from happening by blocking your ears? (Sound vibrations are not reaching the ear drum/tympanic membrane.)
Explain that whales have no outer ear or ear canal to funnel the sound. Tell them that they are going to watch a video that will explain how whales hear.
2. Distribute to each student a copy of the handout titled Using Scientific Inquiry to Explore Whale Hearing (PDF) Give students a few minutes to review the questions on the handout. Tell students that, as they watch the next video clip on whale hearing, they should listen for answers to those questions.
3. Have students watch the Guess How Whales Hear! video and work with a partner to answer and discuss the questions on the handout. Students may need to watch the video more than once.
4. As a class, discuss how Dr. Ketten used scientific inquiry to figure out how whales hear. Ask students whether they thought she did a good job explaining her findings.
5. Hand out the Whale and Human Ears (PDF) diagram (from the lesson Questions about Hearing). Complete the diagram as a class. See if students can identify some of the ear parts of the whale based on what they know about the human ear.
6. Explain to students that now they are going to work with a partner to model how whales hear. Distribute How do whales hear? (PDF) to each student, along with the materials needed to conduct the experiment.
7. Review the handout with students. Make sure they write their predictions down before they do the experiment. Then have them conduct the experiment, record their observations, and use them to construct a reasonable explanation for what they found.
What will students hear? A church bell sound (dong-dong)
What's going on? Hitting the spoon causes it to vibrate. These vibrations (or sound waves) are conducted up the string, through the fingers, through the bones of the skull and into the inner ear. Because the sounds are traveling through solids (instead of through air), they sound much louder and deeper than they normally would.
How is this similar to how whales hear? Sound waves travel through water, just as they traveled through the string, alerting whales to sounds that are generated miles away. Because under water sounds are traveling through liquid (a much better conductor than air), they too seem much louder than similar sounds traveling through air. The student's fingers are acting somewhat like the fat pads in whales. The fingers and the fat pads both conduct sound vibrations to the inner ear. Since sound waves travel through liquids and solids, under water animals don't need "ear flaps" and ear canals the way land animals do. However, our experiment is not a perfect model for how whales hear. String and fingers are made up of different materials than water and fat, so sound doesn't travel through them in exactly the same way
8. Have the students try a slight variation of the experiment: Tell them to put their index fingers gently into their ears, so that they just barely touch the bones surrounding their ear canals. Now have them hit the spoon on the desk. Discuss their observations.
What will they observe? They will feel the vibration passing from their fingers to their ear canal.
9. Discuss students' findings as a class. What conclusions can they make?
Make sure students understand that the ability to hear is due to one's ability to detect vibrations.
10. For homework, have students read the article on the effect of underwater noise pollution on fish.
11. Optional: Have students repeat the experiment with different-shaped metal and wooden forks and spoons, and different types and lengths of string. Encourage them to mix and match materials to investigate the properties sound [pitch, volume, and timbre (sound quality)].