Sound/Pitch

Joan Cwiklik                   O.A. Thorp Scholastic Academy
                               6024 West Warwick Avenue
                               Chicago, Il. 60634
                               312-534-3640

Objective:  
    
To discover how pitch can be changed in instruments that are plucked (strings), 
blown (woodwinds and brasses) or hit (percussion). 

Bottle Music

Materials Needed:

Each group needs 5 bottles of the same size (empty pop bottles work well), 
water.  Optional:  Funnel (for filling bottles).

Strategy:

1.  Fill one bottle with water almost to the top.  Fill the second bottle about 
    three-fourths full, the third half full and leave the last bottle empty.
2.  Blow across the top of each bottle.  Listen to the highness/lowness of each 
    bottle's note.
3.  Record your data.

Conclusions:

When you blow across the top of each bottle, it makes the air inside the bottle 
vibrate.  Small air spaces vibrate more rapidly than large air spaces.  When 
there is little air in the bottle, you produce a high note.  When there is more 
air, the note is lower.

Underwater Recorder

Materials Needed:

Each child needs his recorder, duct tape and a tall container of water.

Strategy:

1.  Cover all the finger holes in the recorder with duct tape.  Blow gently into
    the recorder and you should hear a single, low-pitched note.
2.  Take a deep breath and blow into the recorder while you push it into the 
    water.  What happens to the pitch of the note?
3.  Take another breath and blow into the recorder again while you pull it up 
    out of the water.  How does the sound change?

Conclusions:

When you blow into the recorder, the air inside it vibrates and you hear a 
note.  The pitch of the note depends on the length of the column of air inside 
the recorder.  When you push the recorder under the water, the water fills up 
the tube so the column is shorter.  You hear a high-pitched note.  As you pull 
the recorder out of the water, the column of air becomes longer and the note 
sounds lower.

Pipes of Pan

Materials Needed:

Five pieces of bamboo or hollow plastic (PVC) piping, cut into the following 
sizes: 2, 31/2, 5, 61/2 and 8 inches; non-drying modeling clay and sticky tape.

Strategy:

1.  The pieces of pipe are cut to different lengths ranging from 2 to 8 inches. 
2.  Push a piece of modeling clay into one end of each tube.
3.  Arrange the pipes in order of length, with the shortest pipe at one end and 
    the longest pipe at the other end.  Tape the pipes together so the open ends 
    are exactly level with each other. 
4.  To play your Pipes of Pan, place the edge of the open end of the pipe 
    against your lower lip and blow gently across the top of the pipes.
5.  What do you notice about the pitch of the notes from the different pipes?

Conclusions:

You should discover that the longer pipes give lower notes and shorter pipes 
make higher-pitched notes.

Glass Xylophone

Materials Needed:

For each group:  5 glass containers that are the same size (such as empty pop 
bottles), water, wooden spoon or mallet, funnel for filling bottles.

Strategy:

1.  Fill one bottle with water almost to the top.  Fill the second bottle about 
    three-fourths full, the third half full, the fourth a quarter full and 
    leave the last bottle empty. 
2.  Tap the side of each glass gently with a wooden spoon.  Each glass will ring 
    with a note of a different pitch.  Which glass makes the highest sound and 
    which glass makes the lowest sound?

Conclusions:

When you tap each glass, it makes the glass vibrate.  The pitch of the note 
depends on the amount of water in the glass.  With more water, the pitch of the 
note is lower.

Other activities which were demonstrated include Elastic Band Guitar for 
exploring stringed instruments and Tapping and Hitting for discovering pitch in 
percussion instruments.