Sound and Hearing
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Cecile Savage John Farren School
5055 South State
Chicago IL 60609
To demonstrate that sound travels.
To explore how sound is reflected, amplified and recorded.
To investigate the physical components of the ear and the way it works.
This lesson is designed for a 5th or 6th grade class.
one cookie box or cake tin
sauce pan or baking tray and wooden spoon
plastic wrap or balloons
1 or 2 candles
1 tape recorder and microphone
index cards or pieces of smooth posterboard
alarm clock or softly ticking metronome
a blank cassette tape
1 yard of flexible plastic tubing
Sound as waves
Activity #1: Stretch the plastic wrap or balloon over the cookie tin;
secure with rubber band(s) and sprinkle a few grains of uncooked rice over the
plastic. Hold the baking tray over the can. As the tray is being hit with the
wooden spoon, the rice can be seen moving and jumping over the plastic membrane.
This activity shows that sound travels in waves and reaches our ear drum or
tympani much in the same way as it vibrates the plastic over the cookie tin.
Activity #2: Stretch a piece of plastic wrap or balloon over both ends of a
cardboard tube; secure with rubber band(s). Make a little hole in the plastic
at one end of the tube only. With the clay, build a short stand that has the
same height as the candle. Lay the tube over the stand, with the pierced end
pointed towards the candle, and just a few inches away from it. Tap the other
end with your finger. The vibrations blow out the candle. This activity shows
how the vibrations made by tapping the drumhead move down the cardboard tube and
push the air out through the little hole at the opposite end, much like they
travel down our ears. The pitch or tone of sound waves is measured in Hertz.
Waves: direction and reflection.
Activity #3: this is a game for the whole class room. The class sits down
in a circle. One person volunteers to wear a blindfold and sit in the middle.
The other players are quiet and a designated student makes a gentle noise, such
as popping his/her fingers. The blindfolded student must point in the direction
of the noise. Many different players can take a turn at being blindfolded.
Whose ears have the best sense of direction?
Activity #4: Use modeling clay to secure 4 equal pieces of cardboard tube
in an horizontal manner. They must form a zigzag pattern with an angle of about
90o between each tube. Without changing that angle, place a square of
posterboard facing the adjoining end of the first and second tubes, another
square of posterboard facing the ends of the second and third tubes, and a third
piece of posterboard facing the ends of the third and fourth tubes. Place a
microphone hooked to a tape recorder at one end of this contraption. Set a
ticking metronome or alarm clock at the opposite end, but away from the opening
of the first tube. The tape recorder will record either nothing or a very faint
sound. Now, place the metronome right at the opening of the first tube. The
resulting recording should be quite clear. Different experiments can be done:
change the directions of the tubes and determine which direction give off the
clearest sound; or replace the smooth cardboard with reflector cards of
different material or egg cartons. This activity demonstrates that sound waves
in air will bounce off a flat, solid surface, like a ball bouncing off a wall.
If, however, the sound waves are bounced off a surface that is soft or bumpy,
the waves will break up or fade away. Volume is measured in decibels.
Amplifying and recording sound.
Activity #5: making a stethoscope. Take a piece of plastic tubing that
fits tightly over the narrow ends of 2 funnels. Attach a funnel to each end.
Ask a student to put one funnel over his/her chest and another student to put
the other funnel, at the other end over his/her ears. He/she should be able to
hear the other student's heartbeat. This activity demonstrates how some devices
can amplify sound. The shape of a cone is used to amplify sounds whether
receiving them (stethoscope), or sending them (megaphone).
Activity #6: Students face a microphone in a row or two, depending on their
numbers. They sing a song together in the microphone, hooked to the tape
recorder. The tape will pick up the voice nearest to the microphone drowning
the rest. Then, the microphone is tied to the handle of an open umbrella,facing
the students standing at the exact same place. Play the tape back. The voices
are far clearer than on the first recording. The same experiment can be done
recording birds outside. This activity shows students how the umbrella's shape
collects the sound waves and reflects them back to the microphone.
Make a model that demonstrates how the ear works.
Activity #7: Stretch plastic wrap over one end of a tube and secure with a
rubber band. Roll another sheet of paper to make a cone and insert the smaller
end into the other end of the tube. Stand an index card in a vertical way,
(secure with modeling clay) very near the end of the tube with the plastic wrap.
Shine the flashlight on the plastic wrap so that the light is reflected onto the
card. Then shout or sing loudly into the cone. Results: the reflected light
should flicker. The cone represents the outer ear (pinnea), the tube is the ear
canal and the wrap represents the ear drum (tympanic membrane). When sounds are
captured by the outer ear and travel down the ear canal, the eardrum vibrates.
Students should be able to retrace any experiments of their choice step by
step. They should know how to explain the following terms: hertz, decibel,
stethoscope, pitch, volume, outer ear, ear canal, ear drum, amplify, sound wave,
string, wind and percussion instruments.