Sound and Vibrations

Materials  Student Sheet no. 4 called The Tuning Fork  Student Sheet no. 5 called The Long Gong  Cord with bead  Wood blocks  Tone generator  Beans  9-V Battery  Meter tape  Nail  Pliers with wire cutters  Scissors  Tape  Plastic cups with a hole in bottom per pair  plastic cup full of water per pair  Ping-pong ball per pair  Thread (30 cm)  Paper towel  Tuning fork per pair  Wire coat hanger  String (40 cm)  “Animal Babble and your Source and Receiver” from story book

Before Class Set Up Door Fiddler (for teacher)  Slide cord under the door and pull until the bead is snug behind the door.  Loop the cord over the top of the door.  While pulling down on the cord behind the door, slide the loose end under the door again.  Make as tight as possible.  Wrap the remaining length of cord tightly around the door knob 2 or 3 times.  Use slit knot to tie off.  Slide a wood block flat under the strings below the know, and stand it up.  Page 22 Picture

Before Class Set Up Long Gong (for teacher)  Cut string 40 cm long.  Poke a hole in the bottom of a cup with a nail, run one end of the string through the hole, and tie a knot.  Tie the loose end of the string to the center of the bent hanger.  Place long gong in plastic bag.

Door Fiddler  Pluck the longest string.  What do you hear?  What do you see?  How does the string feel when it is making its sound?  Pluck the shortest string.  How are these sound different?  Move wood block and pluck top and bottom of string.  What happened?  The back and forth movement of the string is called a vibration. Sometimes vibrations are so fast that they are easier to feel than they are to see.

Tone Generator  Place beans on speaker  Adjust the pitch and volume  What do you hear?  What do you see?  How does the speaker feel when it is making its sound?  The back and forth movement of the speaker is called a vibration. Sometimes vibrations are so fast that they are easier to feel than they are to see.

Tuning Fork  Demonstrate how to hold the tuning fork by the stem  Strike the wood block or the sole of your shoe  Gently strike it once  Hold it firmly  Bring the fork near your ear and listen  3 minutes to explore  What did you hear?  What did you see when the instrument made a sound?

Long Gong  Place cup over one ear  Lean forward so string hang freely  Use the pencil to gently strike the wire, string, or cup once  Listen  3 minutes to explore  What did you hear?  What did you see when the instrument made a sound?

Pass out The Tuning Fork sheet

Pass out The Long Gong sheet

Listening Activity  Close eyes, be very quiet, and listen carefully.  After 1 minute, identify sounds heard

Sound Source  Sound comes from a sound source.  A sound source is where a vibration starts.  Usually a sound source is a vibrating object, like a tuning fork and speaker.  What are some examples of sound source? (whistle, teakettle, voice)

Sound Receiver  In order for a sound source to be heard, it must be detected by a sound receiver.  A sound receiver is something that responds to vibrations generated by a sound source.  Our ears are our sound receivers.  Name other sound receivers. (telephone mouthpiece, microphone, animal ear)

Discussion  On the tone generator, what is the sound source? (speaker)  What is the sound receiver? (ear)  How does the sound change? (louder or softer)  What happens to the vibration when the sound is louder or softer? (Vibrations are stronger when the sound is louder. Vibrations are weaker when the sound is softer.)

More Discussion  Where have you felt vibrations and what sounds did you hear? (musical instruments, bells, drums)  What causes sound? (vibrations)  What is volume? (how loud a sound is)  Read “Animal Babble and your Source and Receiver”

The End!!!