NS.5-8.1 Science as Inquiry NS.5-8.5 Science and Technology NS.5-8.7 History and Nature of Science
marine mammals, Humpback whale, underwater, acoustics, vocalization, sound, tracking, migration, Glacier Bay National Park, whales, ocean, research, science
Students will learn that humpback whales make different vocalizations. They will discover how scientists can use technology to track whales by listening to their vocalizations. Students will engage in a role play activity that simulates the tracking of whales using hydrophones as they migrate between Alaska and Hawaii.
How do scientists record and analyze underwater sounds?
What can scientists learn about whales by listening to their sounds in the sea?
How can this information help scientists in their efforts to protect whales and other marine animals?
Our "Underwater Acoustics" curricula unit is divided into three lesson plans, each taking one class session to complete. They are part of our "Middle School Scientists" series that explore the fascinating research and resources of Glacier Bay National Park.
Studying whales can be challenging. Whales are often in remote oceans where there are few boats. Whales spend most of their life underwater out of sight of people. Scientists had to find a different way to track whales. Whales are very noisy and vocal animals. They sing songs, make audible blows, and communicate vocally during feeding and mating. Like people, whales also have different accents and voices. Some vocalize at a higher or lower pitch, or sing faster or slower. Whale calls even have regional differences: humpback whales in the Southern Hemisphere sing a little differently than humpback whales in the Northern Hemisphere. Scientists can track whales by the unique noises they make.
Each whale, like anything that makes noise, is a sound source. Hydrophones can record the noise of the whales underwater. Using hydrophones, scientists can determine where whales are, how many there are, where they are going, diving depth, and more. However, scientists need accurate soundreceivers. For humans, our ears are sound receivers. They are what we use to hear. Not only can ears hear, but they can also determine direction. Since our ears are on two different sides of our head, they hear things at slightly different rates. If the sound source is on the right side of a person, the person's right ear will hear the noise slightly before the left ear. This is called the time of arrival difference and allows us to determine which direction a sound is coming from. Sometimes a sound source may be the same distance from each ear and it is hard to determine where the sound comes from. If we had three ears, it would be easier, but no one has three ears. However, we can have three (or more!) hydrophones recording the same whale. Underwater listening stations in the North Atlantic and North Pacific can do this. Using a process called triangulation, scientists use the time of arrival difference between several sound receivers (hydrophones) to determine where a whale vocalized.
During this activity, students will listen to a variety of humpback whale vocalizations from the clips provided. Give students copies of the Humpback Whale Photo Gallery and Whale Vocalizations Table. The images can help the students visualize humpback whales in their marine environment as you play the clips.
Play each audio clip. Have the students listen carefully to the different humpback whale sounds. Allow the students some time to write down descriptions of the sound on the Whale Vocalizations Table. They may use terms like grunt, groan, song, click, moan, etc. Discuss and record why they think the whale is making that noise.
(adapted from On the Trail of a Whale, Discovery of Sounds in the Sea, and Searching for Sounds in the Seas, Sea Grant Alaska)
Before you begin, make copies of the Whale Tracker Data Sheet for each group. Tell students that today they will have a chance to become whale trackers (hydrophones), whales, and researchers (data recorders). They will be using their sense of sound to identify and locate different humpback whales.
Mark out an open area with longitude and latitude lines. Every five feet should represent 20 degrees of longitude and latitude. Show students copies of the Pacific Ocean map and identify Alaska, North America, and Hawaii. While standing in the activity area, have them identify longitude and latitude lines by locating a given coordinate. Call out two coordinates and ask for a volunteer to stand on that coordinate. After students become familiar with navigating the map, designate five students to be whale trackers (hydrophones), five students to be humpback whales, and one student to be a researcher (recorder).
Students representing whales will each make a different, unique noise. Each student could make a different animal noise, say their name, sing a song, or (for an extra challenge) imitate a whale noise.
The whale trackers will listen to all five noisy humpbacks, but they will be trying to identify a specific whale. Blindfold each tracker or have them close their eyes.
The whales, each with their unique vocalization, will wander around the playing area making their noise. The teacher will choose a noise for whale trackers to listen for. They will try to track that whale. For example, if the teacher says track the whale making the feeding call, the trackers must filter out all other sounds and point in the direction of the whale making the feeding call.
When the whale trackers think they hear the given vocalization, they point in the direction of the whale. When three trackers are all pointing at the correct whale, the game stops and the researcher records the longitude and latitude of that whale on the Whale Data Sheet.
Repeat this activity for each whale vocalization, having students change jobs as needed.
After the activity is completed, the Whale Trackers should plot the detected locations of their whales on the Humpback Whale Migratory Routes page.
Using technology, scientists can gather underwater sound data to help make informed decisions regarding current and future management policies. Use the following questions to help students reflect on the activity. What difficulties might scientists have using this method of gathering data? What can scientists learn by tracking whales?
Underwater Acoustics Assessment
The following pre and post-tests provide assessment for material covered by the
entire Underwater Acoustics Curriculum series (Lessons 1-3)