Main Idea
Sounds are all around us. Understanding how sound is produced makes
it possible for us to manipulate it so we can decrease the number of
unpleasant sounds created by things as diverse as airplanes and vacuum
cleaners.
Background
Sound is caused by a movement or vibration created by force.
Some vibrations cause air to move, to create sound waves that we can hear.
The pitch of the sound (how high or low the sound is), depends on
how fast an object vibrates. The volume (how loud the sound is),
depends on the degree of force used to make the object vibrate. When we
increase the volume of a sound we are amplifying it.
With drums, we strike the skin to create a sound. The force that causes
the vibration is the blow on the drum. The harder we strike, the louder
the sound. You can manipulate the pitch of a drum in three ways: 1) tighten
the drum’s skin to make the pitch higher; 2) put a thicker skin on
the drum to lower the pitch; and 3) strike the drum closer to the center to
produce a slower vibration and lower pitch, which sounds more resonant.
Learning Objectives
- Understand the concepts and differences between force, pitch and volume.
- Explore the science of instrument design and construction.
- Explore the field of sound engineering.
Time
1 & 1/2 hours (allow at least 1/2 hour for design)
Introducing the Concept
Discuss how force is needed to produce vibration and how different kinds
of vibrations produce a variety of sounds. Demonstrate how force is used
to make drums vibrate.
Materials
- different-sized, wide-mouthed jars without lids
- paper - tissue paper, letter paper, construction paper, other types
of paper
- balloons
- rubber bands large enough to fit the mouth of the jar
- wooden sticks (chopsticks are ideal) or wooden spoons
- rice, small lentils or peppercorns
- paints, markers and other design material
Hands-On
Drums can be made with just about anything. Using the materials provided,
design a drum.
- To make a drum, place paper or a balloon over the mouth of the jar.
(You might even try placing the paper down with a balloon on top of it.)
- Place the rubber band around the mouth of the jar to secure the
paper/balloon skin.
- If you like, place some rice on the skin so you can observe the vibration
as you apply force to the drum. Be sure to spend some time designing the
exterior of your drum.
Minds-On
- Tap on your drums to produce sound.
- Is it different than that of other students’ drums?
- Do different skins produce different sounds? What might cause these
differences?
- Do different sizes of jars produce different sounds? What would happen
if you filled the jars with something? Does it sound the same?
- Are different sounds produced when you strike different parts
of the skin?
- What happens to the sound when you increase the force with which you
strike the drum? Does the pitch or volume change?
- What happens when rice is placed on the drum? Can you see the vibrations?
Does it affect the sound?
- What causes the rice to react differently when you strike the skin
harder?
Teaching Tips
- Before doing this activity, you may want to test the paper you will
be using for drum skins to be sure it doesn’t tear too easily.
- Try having the students work in groups of four when they are testing
the drums.
Science All Around Us
Various cultures throughout the world use drums as a way to communicate.
Drum beats can signal warnings or transmit elaborate messages, much like
Morse code, as long as the person receiving the message is within earshot.
Have the students design their own drumming code so that they can send
secret messages to their classmates.
Interconnections
Drums have been used throughout history for religious, spiritual, technical,
musical and recreational purposes. Have the students identify the types
of drums used by their own culture and share the story of these drums with
their classmates. They may even want to tell their story while beating
a rhythm on a drum.
Sounds Like Science - Guitars
Sounds Like Science - Kazoo
Sounds Like Science - Bottle Organ
Sounds Like Science - Jamboree
This activity copied from APASE of Vancouver, Canada, which
has regrettably disappeared from the Web.