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.
Check out the other lessons:
Marine animals rely on sound to acoustically sense their surroundings, communicate, locate food, and protect themselves underwater. Some predators, like orcas (killer whales) and dolphins, use echolocation to find prey. By emitting short pulses of sounds called clicks, these marine mammals listen for echoes to detect prey and navigate around obstacles. Similarly, some fish are able to hear the killer whale clicks and avoid capture! Because these animals live in a relatively dark environment, being able to "see" acoustically is important to their survival. Engineers have mimicked this natural echolocation in SONAR (SOund Navigation And Ranging) which works the same way as echolocation in animals.
Some blind people use sonar by listening to the echoes from taps of their canes to help them avoid objects or help them determine how far they are away from a wall. Sound travels faster and farther underwater than through air. This means that sounds produced by marine animals and humans can travel great distances without much loss to the quality of the sound. These sounds are often reflected by underwater topography making it tricky to communicate using sound underwater. Marine mammals must be able to sort out all the echoes in the water in order to effectively communicate and feed. Whales and dolphin anatomy and sensory systems are adapted to meet this challenge.
While humpback whales do not echolocate, they do use sound to communicate and may use sound to navigate and find food. Glacier Bay is currently studying the effects underwater sound may have on the feeding behavior of endangered humpback whales. Research shows that whales may move away from preferred feeding areas when disturbed by boat noise. Repeated disturbances could be detrimental to Alaskan humpbacks, who must feed enough during the summer to sustain themselves through their 3,000 mile roundtrip migration to and from Hawaii. Additionally, increased ambient noise, or background noise, may make it difficult for humpback whales and other animals to communicate, find mates and more.
Tell students they are going to hone their sense of hearing by using their hands to make "cups." Teach them how to cup their hands around their ears facing forward, then backward. This will help focus sounds to their ears. Tell them it may be useful during the next investigation. Allow them to experiment with their new "ears" by trying to focus on a sound in the room. You can have a student go to the back of the room and clap.
Ask students to carefully listen to several underwater sounds from the clips provided. All of these sounds were recorded using the hydrophone in Glacier Bay. Listen to all six, so students will have the opportunity to discriminate between human-made, animal, and other natural sounds. As you play each clip, have students try to identify the sound source (what is making the sound) and write it in their journals. Ask students to explain experiences they've had with sound underwater.
Other Natural Sounds
Talk about the results and discuss why some locations were harder to guess than others. Did anyone use their "cups" to focus sound during the activity? Encourage students to think about why ambient noise made it harder to guess the location of the finger snaps. How might this noise affect marine animals? Why is it important for researchers to study sound in Glacier Bay? How could park managers eliminate or moderate human caused sounds that may disturb wildlife in Glacier Bay?
Underwater Acoustics Assessment
The following pre and post-tests provide assessment for material covered by the
entire Underwater Acoustics Curriculum series (Lessons 1-3)
Have students compile their data and make comparisons. Create one large chart or bar graph using computer programs like Excel or Word Charts/Graphs. For a more challenging activity, have students plot actual location of snap versus real location and then find the percent of correct responses.
Have students watch the short four-minute video, Dean Hudson, acoustic navigator. Dean is visually impaired and uses sound clues to navigate the city. Have several students wear blindfolds or close their eyes while making sound. They can either clap or snap their fingers. See if they can interpret the echoes to navigate around the room without bumping into objects or a wall. Be sure to give them plenty of space and use some students as monitors to help prevent trips or falls.
Here is the link to Dean Hudson's video: http://www.exploratorium.edu/listen/lg_dean.php
Glacier Bay National Park acoustics monitoring research
Enjoy this fun video produced by park researchers and local students.
University of Colorado, Teach Engineering - Resources for K-12.
The Cornell Lab of Ornithology, Effects of Human-Made Sound on the Behavior of Whales
Bamfield Marine Sciences Centre Public Education Program
Oceanlink, An Ocean of Sound - An Exploration of Underwater Acoustics
Exploratorium, The Listen Project.