Transcript sound - davis.k12.ut.us

Sound
Part 1
Another form of energy is sound
▪ Vocabulary words you should know and listen for while watching Bill Nye
are:
– Sound (duh!)
– Vibration
– Pitch
– Absorption
Bill Nye Quiz Questions
1.
A(n) __________ is an instrument that visually shows the changes in a varying current or frequency of
sound waves.
a. laser
2.
b. microscope c. oscilloscope
Which of the following is an important term related to sound and music?
a. frequency b. pitch
3.
c. vibration
d. all of the above
A ________ creates sound by making air molecules vibrate at certain frequencies and can be used to fix
the sound of an out-of-tune instrument.
a. divining rod
4.
d. telescope
b. rhythm spoon c. treble staff
d. tuning fork
How many quarter notes make up a half note?
a. 1
b. 2
c. 4
d. 6
5. ___________ discovered that the octave had a ratio of two to one and used the idea to develop the musical
scale.
a. Galileo
b. Plato
c. Pythagoras
d. Socrates
Bill Nye Quiz Answers
1.
A(n) ____________ is an instrument that visually shows the changes in a varying current or frequency of
sound waves.
C.
2.
Which of the following is an important term related to sound and music?
D.
3.
Tuning fork
How many quarter notes make up a half note?
B.
5.
All of the above
A ________ creates sound by making air molecules vibrate at certain frequencies and can be used to fix the
sound of an out-of-tune instrument.
D.
4.
Oscilloscope
2
_________ discovered that the octave had a ratio of two to one and used the idea to develop the musical
scale.
C.
Pythagoras
What is Sound?
▪ Turn to page 1 in your books (draw glasses at the bottom of the page then
read)
▪ Turn to page 2. If a tree falls in a forest and no one is there, does it make
a sound? Why or why not? Let’s talk about it…what do you think?
▪ We’ll get back to the answer at the end of the lesson
▪ Sound is a form of energy caused by vibrations.
▪ Vibrations are the rapid back and forth movement of molecules.
▪ Sound energy is transmitted by vibrating an object.
How sound happens
▪ Let’s write down the 8 steps how sound happens
1.
Pluck the string
2.
The string vibrates
3.
Molecules around the string vibrate
4.
This causes more molecules to vibrate
5.
The vibration continues to travel through the molecules
6.
The vibration reaches your ear
7.
Your eardrum and other bones vibrate
8.
This tells your brain you’ve heard a sound
▪ Choose an instrument that does not have strings. How does it produce
sound?
▪ For instance:
▪ Instrument: Drum
▪ How it produces sound: Strike the drum. The drum vibrates. This vibrates
molecules which travel to your ear. Your ear bones vibrate and you hear a
sound.
▪ Instrument: Recorder
▪ How it produces sound: You blow into the recorder making a vibration, this
vibrates molecules, your ear bones vibrate, you hear the sound.
Tuning Fork
▪ Turn to page 3
▪ Have you seen one of these before?
▪ What does it do?
▪ Let’s see if we can get it to make a sound
▪ What will happen if I place the tines in water? What if I exert more energy upon the
tuning fork and place it in water again?
▪ Why? The tines vibrate, which vibrates the water.
▪ What will happen if I only place the handle of the tuning fork in the water after hitting
it?
▪ Why? The handle is not vibrating, so it will not vibrate the water.
▪ How does sound travel?
▪ Sound travels in a wave.
Sound travels in waves
▪ We are going to see how a slinky can be used to show sound waves
▪ https://www.youtube.com/watch?v=_vYYqRVi8vY
▪ https://www.youtube.com/watch?v=4GBBSomUY90
▪ Let’s try it, too
▪ Draw this in your book
How does the Slinky relate to the Molecule
Model?
• The coils of the slinky actually represent the molecules in the air.
• As sound waves travel through air, the molecules compress and stretch apart just like the
coils of the slinky
• Let’s draw a group of molecules close together (these are compressions), when they are
stretched apart, they are rarefactions
• Let’s add the sound wave.
• The wave is up high (crest) when the molecules compress and is down low (trough) when
they rarefract.
• The distance from one crest to another or one trough to another is known as one
wavelength.
Circle Model
▪ Here’s another model to show you how sound waves travel.
▪ I need 2 volunteers
▪ I need one person to sit down on the floor and one person to stand on a chair
▪ Remind me to take off the microphone 
▪ I’m going to stand in the center of the room…and talk
▪ Raise your hand if you can hear me
▪ Even though I was only talking in one direction, how come everyone could hear
me?
▪ Sound travels in all directions from its source.
▪ Let’s draw the circle model
In conclusion
▪ If a tree falls in a forest and no one is there, does it
make a sound? Why or why not?
▪ When the tree hits the ground, it causes the ground to
vibrate. This causes the molecules to vibrate, and
those vibrations spread out in all directions from the
source. If the vibrations in the air reach your ear,
you will hear the sound. However, even if you are
not there, the vibrations still exist, so the sound still
occurs.
▪ Fill your answer in on page 4
Since we talked about water in glasses…
▪ https://www.youtube.com/watch?v=_b-7P-XsnUI
▪ https://www.youtube.com/watch?v=gzf9hITzuOM
And strings on a guitar
▪ https://www.youtube.com/watch?v=ERjE22bwFcA
▪ https://www.youtube.com/watch?v=nM0xo1xZtP0