Download Lesson 4: Hearing

OMSI: OBP
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In this lesson, students work in small, collaborative groups to investigate the sense of hearing.
Students choose a question to investigate, design and carry out their experiments, and collect and
analyze their data.
10 minutes for introducing the activity
25 minutes for the activity
10 minutes for discussion
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Hypothesize about the sense of hearing.
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Carry out scientific inquiry and research to learn about the sense of hearing.
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Summarize results in class discussion.
Observing
Predicting
Questioning
Hypothesizing
Investigating
Comparing/Contrasting
Designing Experiments
Interpreting Data
Working Cooperatively
Communicating
From a baby's cry to Beethoven's 9th, all of the sounds we hear are caused by vibrations. A vibrating
object, such as a pair of vocal cords or a violin string, produces waves of energy called sound waves,
which move through the air (and other matter). The outer ear collects these sound waves and funnels
them into the ear canal, where they hit the eardrum, causing it to vibrate.
The vibrations are then passed along through three tiny bones (malleus, incus, and stapes) in the
middle ear to the cochlea, a spiral-shaped, fluid-filled structure in the inner ear. Inside the cochlea are
tiny hairs that respond to different frequencies of vibrations. These hair cells then produce electrical
signals, which travel along the auditory nerve to the brain where they are interpreted as sounds.
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Our sense of hearing is limited to certain frequencies of vibrations, from about 20 to 20,000 hertz (Hz).
Many other animals have a wider range of hearing. Dogs, for instance, can hear sounds with
frequencies between 15 and 50,000 Hz, while porpoises have the astonishing capacity to detect
sounds from 150 to 150,000 Hz.
auditory nerve: nerve that carries signals from the inner ear to the brain.
cochlea: fluid-filled, coiled structure in the inner ear, which contains the hair cells that allow us to hear.
The cochlea is about the size of a pea!
inner ear: structures including the cochlea, in which vibrations are converted to electro-chemical
signals that are sent to the brain for processing.
middle ear: structures including the eardrum, malleus (hammer), incus (anvil), and stapes (stirrup),
which amplify and pass vibrations along to the inner ear.
outer ear: the external ear and ear canal, structures that channel sound to the middle ear.
Introducing the Activity (per class)
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blindfold
Activity (per group)
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materials for making a variety of sounds, such as rice, sand, marbles, coins, bells, paper, pieces
of foam, and pieces of wood
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containers such as film canisters or plastic bowls with lids
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earplugs (one pair per student)
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blindfolds (one per student)
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1 meter length of vacuum cleaner hose or other plastic tubing
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tape measure or meter stick
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Gather and prepare the necessary materials.
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Make copies of Worksheet 4 (found at the end of the lesson).
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Students should not put anything but earplugs in their ears.
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Students should never share earplugs.
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Students should not expose their ears to loud sounds.
1
Ask students what they already know about the sense of hearing. Write their
responses on the board.
2
Ask students what advantages there might be to having two ears rather than one.
Is it easier to determine where a sound is coming from with one ear or two? Then
have students try the following activity:
3
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Have students sit in a circle on the floor. Have one student sit in the center
of the circle and wear a blindfold. Have another student record data on the
board. The student in the center will be trying to use his/her hearing to
determine the source of a sound.
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Point to a student in the circle and have him/her clap hands.
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Have the student in the center point in the direction of the sound.
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Repeat the process a few times. Then have the student in the center plug
one ear (with an earplug or a finger) and try the experiment again. If you
have time, let other students take a turn in the center.
Discuss students' observations and what the activity tells us about our sense of
hearing. (Students should find it is much easier to locate the source of a sound
with two ears rather than one.)
Procedure
Ask students what questions they have about the sense of hearing. List their
1
questions on the board.
2
As in Lesson 3, help students evaluate their questions to find ones that are
testable in the classroom. Possible testable questions include the following: How
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can you improve your hearing ability? What is the quietest (most distant, highest,
lowest, etc.) sound you can hear? Can you hear sounds better through some
materials than others? How does wearing earplugs affect your hearing?
3
Give students the materials and let them decide which question to investigate.
Each group should design an investigation, carry out testing, and record and
interpret their data.
4
Bring students back together to share the results of their experimentation. Let
each group explain how they carried out their investigation, what they observed
about the sense of hearing, and what questions they still have. Encourage
students to offer explanations for their observations.
5
As homework, give each student a copy of Worksheet 4. Encourage students to
experiment further or do other research to answer the questions.
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Ask students to sit quietly at their desks and listen for sounds. What sounds can still be heard in
a quiet room? Have students list all the sounds they hear and then discuss their observations.
(This activity can also be done outdoors.)
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Fill pairs of film canisters (with lids) with different types of small objects, such as coins, rocks,
rice, sunflower seeds, or marbles. Mix up all the canisters and let students use their sense of
hearing to try to match up the pairs.
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4
HEARING
Name/s ____________________________________
Date _____________
Experiment or do research to answer the following questions.
1. How does the ear work? Label the parts of the ear
and tell what each part does.
2. Why is it easier to tell the source of a sound with two
ears rather than one?
3. Where is the sense of hearing processed in the brain?
4. How is sound intensity (loudness) measured?
5. What types of sounds can hurt our ears? How does sound hurt our ears?
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6. How can we protect our hearing?
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Lesson 4 | Lesson 5 | Lesson 6 | Lesson 7
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