Investigation 1: Dropping In Part 3 Sound and Vibrations PHYSICS OF SOUND

OBJECTIVES  I can identify a sound source.  I can identify a sound receiver.  I can describe, orally and in writing, what happens to vibrations when volume changes.

SOUND AND VIBRATIONS  We will be exploring sounds made by two different objects. Watch how to use each object appropriately.  Long gong  Tuning fork  Treat the instruments with care.  If you hit them too hard, they may break.

TUNING FORK AND LONG GONG  You will get time to get to know the instruments, then you will use them for an investigation.  5 minutes to explore  Repackage instrument  Switch with another group  GETTERs get materials.  STARTERs watch the clock and make sure everyone gets a turn.

SHARE OBSERVATIONS  Return all materials to the bags.  Think-Pair-Share  What did you hear?  What were the properties of the sounds you heard?  What did you see when the two instruments made sounds?

DOOR FIDDLE  Guess what the teacher is making.  What do you see?  What do you hear?  How does the string feel when it is making its sound?

TONE GENERATOR  Watch the beans!  What do you see?  What do you hear?  How does the speaker feel when it is making its sound?

TONE GENERATOR  The quick back-and-forth movement of the string and speaker cone that you observed is called a VIBRATION.  Sometimes vibrations are so fast that they are easier to feel than they are to see.  Some vibrations feel like a tickle or a buzz.  Where have you felt vibrations? What did you hear when you felt the vibration?

INVESTIGATE  We will use the long gongs and tuning forks to do detailed investigations.  This time you should look for vibrations when the turning fork and the long gong are making their sounds.

STUDENT SHEETS  Open your yellow Physics of Sound packet to “The Tuning Fork” and “The Long Gong.”  Look at the headings. You will be expected to record information on these sheets while you investigate.  READ THE INSTRUCTIONS CAREFULLY.  Underline key words!

MINIACTIVITIES  STARTERs read the instructions aloud to the group.  After that, GETTERs get the materials.  When you are done with one activity, have a teacher check your sheet. They will let you know if you can move on to the next activity.

THINK ABOUT  What causes sound?  What is vibrating when you hear the sounds?  T-P-S  Return materials.

THE SOURCE  Close your eyes. Be VERY quiet. Listen carefully to the sounds all around you for the next minute or so.  Raise your hand and identify a sound you heard.  Sound comes from a source. A sound source is where a vibration starts. Usually a sound source is a vibrating object, like a wire arch, a tuning fork, or a speaker cone.

THE RECEIVER  In order for a sound source to be heard, is must be detected (found) by a sound receiver. A sound receiver is something that responds to vibrations generated by a sound source.  Our ears are our sound receivers.  What other sound receivers can you think of?

VOLUME  Demonstration: work with volume dial on tone generator, keeping the pitch the same.  What is the sound source?  What is the sound receiver?  How is the sound changing?  What happens to the vibrations when the sound is louder or softer?

VOLUME  Volume describes how loud a sound is.  STRONG vibrations make LOUD sounds.  Weak vibrations make soft sounds.  Volume is measured in decibels, named for Alexander Graham Bell, the inventor of the telephone.

VOLUME  Explore volume with the door fiddle, tone generator, tuning fork, and long gong.  Identify the sound sources and receivers.  How intense (strong or weak) is the vibration while the sound is being made?

OBJECTIVES  I can identify a sound source.  I can identify a sound receiver.  I can describe, orally and in writing, what happens to vibrations when volume changes.

REVIEW/REFLECT  What do vibrations have to do with sound?  What are some examples of sound sources?  What are some examples of sound receivers?  What happens to the vibrations when the volume changes?

SOUND

VIBRATION

SOURCE

RECEIVER

VOLUME