1. Sound Experiments

2. How boring would life be without different sounds?
Bueller?

3. Sound Experiments Turn to page 5
Everyone should receive 4 rubber bands. Use them appropriately.
Let’s pluck the thickest rubber band
What do you notice? Slow vibration, low sound
Thick band? Low sound
Thin band? Normal sound
Thinnest band? Faster vibration, high sound

4. Sound Experiments Now, you will all get a large and a small paperclip
Unfold it, partially, like this…
Let’s pluck the small paperclip
What did you observe? High sound, “clicking”
Pluck the larger paperclip
What did you observe? Low sound, “thudding”

5. Sound Experiments
Gently place your fingers on the front of your throat and recite the alphabet, when directed 
Try it in a regular voice.
What happened? It vibrates
Now change speed. Quickly then slowly.
What happened? Vibrations change as faster and slower.
Change pitch
What happened? Vibrations change
Change volume
What happened? Throat feels different when loud or soft, and it vibrates.

6. Sound Experiments Turn to page 6
What did all the objects have in common while they were producing sound? They were vibrating.
What did you observe about the rubber bands? They vibrated when plucked to make a sound. The different thicknesses affected their pitch.
What did you observe about the paperclips? They vibrated against the table to make sound. The larger and smaller one sounded different.
What did you observe about your vocal cords? My throat vibrated as I talked. The vibrations changed with the pitch, speed, or volume.

7. Pitch Pitch is a measure of how high or low a tone sounds to your ear.
Pitch depends on the frequency of the sound waves.
Frequency is the measure of the number of waves that pass in a given amount of time.
So, a sound with a low pitch would have a low frequency and would look like this (in your book…)
A middle frequency would look like this, and it would have a middle pitch…
A high frequency would look like this, and in turn, the pitch would be high…

8. Pitch So you can conclude
Greater frequency = more waves = higher pitch
Guitar strings have different pitches. Remember, larger/longer/looser = lower
Your recorders…what if you covered all the holes? What would the pitch be? Remember, larger/longer/looser=lower
ABC song…I’ll dictate the pitch, you demonstrate…

9. Pitch experiments
Stretch a rubber band around the width of a textbook. Place two pencils under the rubber band, one near the left and one near the right edge of the cover. The pencils should both be on top of the book.
Pluck the rubber band and note its pitch in your book on page 8.
Now, place a finger one inch from the right pencil. Before you pluck, how do you predict the sound will change?
You may now pluck the rubber band between the left pencil and your finger. Were your predictions correct?
Log your observations and continue this process for the entire length of the rubber band.
What were your overall observations?

10. Pitch experiments
Hold a ruler firmly against a desktop with 2 inches on the desk and 10 inches in the air. Strum the free end and observe the pitch. Log your observation on page 9.
Repeat the process for the entire length of the ruler with 4 inches on and 8 off, 6 inches on and 6 off, 8 inches on and 4 off, and 10 inches on with 2 off.

11. Pitch experiments
Stretch the end of the rubber band up and over the end of the ruler. Place your finger at the 2cm mark and pluck the rubber band. Listen to the pitch.
Repeat the process placing your finger at the 4cm, 6cm, and 8cm marks and listening to the pitch.
Log your observations on page 9.

12. Applying what we’ve learned
Use what we’ve learned about pitch to answer the following questions about human vocal cords (page 10).
How do we produce sounds? Air passes by our vocal cords causing them to vibrate and produce sounds.
Why are some voices high, while others are low? How would the vocal cords look different for a high voice versus a low voice?
High voice: Tight, thin, short vocal cords
Low voice: Long, thick, loose vocal cords
How can we change the pitch of our voice? To make a high pitch, we stretch our cords thinner. To make a low pitch, we compress our cords to make them thicker.
Here’s a real life video of the vocal cords in action…

13. Mini Quiz Look in your book on page 10
Rank the following glasses filled with different amounts of water from the lowest pitch to the highest pitch.
Answer:
B C A D
Why? B is “longer” or “larger” amount of water, so it’s lower. Let’s prove it…
Larger, longer, looser = LOWER

14. Volume
Have you ever placed your hands over your ears because something was too loud? When? (Answer on page 12 in your book)
Volume is the loudness or intensity of a sound.
Volume depends on the amount of energy used to produce the sound.
You use a lot more energy to yell than you do to whisper.

15. Volume
If you want to play a musical instrument loudly, what do you need to do?
Piano: Pound the keys
Guitar: Strum the strings harder
Drum: Hit the surface harder
Trumpet: Blow hard into the mouth piece
Volume = soft or loud
What’s the difference between volume and pitch?
Pitch is high or low tones
Volume is soft or loud, but your tone can remain the same

16. Think About It
Think about the gym. What are the floor, walls, and ceiling made of? Wood, bricks, cement, tile, etc.
Think about the library. What are the floor, walls, and ceiling made of? Carpet, wood, fabric, etc.
Why do you think they are made of different materials. What purposes do the room serve? How is the sound involved?
Gym: Noisy – used for assemblies, PE, lunch, etc.
Library: Quiet – used for classes, studying, reading, etc.
Sound waves can be reflected off surfaces or absorbed by them.

17. Absorption (page 13) Absorption is the ability to take in or dampen.
Certain materials “soak” up sound like a sponge soaks up water.
To keep areas quiet (like libraries), certain materials are placed in the room to absorb noise.
Examples of sound absorbing materials: carpet, fabric, furniture, insulation, styrofoam, cotton, ceiling tiles, etc.

18. Reflected (page 13)
If sound is reflected from an object, we hear an echo.
In a large auditorium (like gyms), sounds are reflected from surfaces like tile, brick, metal, wood, etc.
This reflection is known as reverberation.
Too much reverberation is unpleasant, but a little gives sound its fullness.
Acoustical Engineers try to design buildings with reflecting and absorbing materials to help the sound travel and still control reverberation.

19. Remember the Abravanel Hall field trip?
What materials were in the audience portion of the building? The floor and walls had carpet.
The seats were covered in fabric. Why? The material helps absorb the sound an audience member might make during a performance.
What if the floor was covered in tile instead? It would reflect sound, which may make audience movement distract from the performance.
What material was on the stage? The floor is wood to help reflect the sounds of the instruments being played.
There is also a large board which stretches behind the orchestra and is angled at the top toward the audience. Remember, sound travels in all directions from its source. It will travel behind the violinist as well as forward, so the board helps to capture the sound waves and send them out toward the audience.

20. Speed of Sound (page 15) Sound travels fast through a solid.
Example: sound of a woodpecker pecking on a tree or a doctor’s stethoscope listening to your heart beat
Sound travels slower through liquids and gases.
Example: talking under water.
Sound does not travel in a vacuum (it needs molecules to vibrate)
A vacuum is a place with no air.
Why can’t sound travel in a vacuum? Pluck the string. The string vibrates, but there are no molecules to carry the vibration to your ear so there is no sound.

21. Is there sound in space?
There is no air in space; therefore, no sound.
If there is no sound in space, how do astronauts communicate? Radios inside the helmets and air in the helmet.
Think about space movies you have seen. Are they accurate? Why or why not? Usually no. There is no air in space so there is no sound or fire. Explosions in space in movies include both flames and loud noises.
Can you hear sound in space? No, but here’s a video indicating planets may make sounds…but how?

22. As a wrap-up…
Mr. Parr “Like an Echo” song
Brain Games
It’s all about that bass
Cool Things Sound Waves Can Do
How sound is used in the future:
Stomp Live
Stomp Live
Stomp Basketball
Hearing Test
Hearing Test