1. Sound & Waves
Palm Pipes

2. Objective
Students will be able to create vibrations, which we hear as music, in order to understand basic properties of sound and waves.

3. Warm up
Using the slinky on your table, demonstrate the movement of a sound wave.
Now demonstrate the movement of a light wave.

4. Focus Questions What are some important properties of sound waves?
What is resonance and why is it important?
What is sound and how do we hear it?
What is music and how do we make music?

5. Palm Pipes Exploration

6. Palm Pipes Check to see the note of your palm pipe.
Follow along with the music and play your palm pipe when your note occurs.
A set of Palm Pipes will be handed out to the participants, there may not be enough for everyone. They are short PVC piping that has been cut to particular lengths that correspond to notes that range almost four octaves. The pipes are played by smacking one of the open ends of the pipe straight down against one’s open and upwards facing palm. It makes a little “poink” of sound with a distinct frequency, which is inversely related to the wavelength ( which will be4x the length of the pipe due to the way air vibrates in the tube). Using the music on the following slides, each person with a palm pipe will “play” their respective pipe when the appropriate note is indicated.

7. Mary Had a Little Lamb
Melody
(1st line) E D C G
(2nd line)

8. HAPPY BIRTHDAY
Melody C D F E G
Harmony A Bb
B b

9. Jingle Bells
Melody E G C D
Harmony F

10. GOD BLESS AMERICA
Melody F E D C G A Bb
Harmony

11. TWINKLE, TWINKLE LITTLE STAR
Melody F C D Bb A G
Harmony E

12. Explanation
How could pipes that have the same note be different lengths?

13. Explanation How does it work?
When you pound the Palm Pipe into the palm of your hand, it disturbs the air molecules inside the tube. The action of these molecules creates the vibration that becomes the note you hear.
The different lengths of pipe create different lengths of sound waves, which in turn create eight different notes.

14. Click this picture for the online wave animation.
Explanation
Click this picture for the online wave animation.

15. Explanation

16. Explanation
Wavelength is the distance from the crest of one wave to the crest of the next.
Frequency is the number of waves that pass a point in each second.
Amplitude this is the measure of the amount of energy in a sound wave.

17. Can you think of other high and low pitched sounds?
Explanation
This is how a high and a low soundwave looks.
A bird makes a high pitch. A lion makes a low pitch.
Can you think of other high and low pitched sounds?

18. Basic characteristics of standing waves
Explanation
Basic characteristics of standing waves
Node
Points where the string does not move
Anti-node
Points where the string moves the most
These terms are very important to the study of waves on the string. Strings behave in ways which allows us to understand waves qualitatively, by describing what is happening, and quantitatively by being able to count and keep track of these features as they change.

19. RESONANCE Explanation
A condition where a force (a push) occurs at a frequency that results in a Standing Wave
These Standing Waves occur at what are called Natural Frequencies or Harmonics.
Every object, substance and material has its own Natural Frequencies, where they “like” to vibrate.
Resonance is a concept that is easy to experience but tough to explain and understand at first. Think of a kid on a swing. To get going the child needs to rock back and forth on the swing to “pump” it to get going. It’s easy to feel when the time is right to pump, but what would happen if the child rocked back and forth at the wrong times? If you were pushing the child on the swing, what would happen if you tried to give a push while the little person is moving toward you instead of moving away? In both cases the push would not result in the child swinging very much. We might say that the timing is off, and these conditions are the same as all the frequencies that DO NOT result in a standing wave on the swing. However, when you do push the child on the swing at just the right time, think just the right frequency, it does not take very much push to get that kid really moving. All of the force you apply to the system is going towards a total increase in energy. If your timing is off, your force works against going higher, it may even stop the swing all together.

20. FREQUENCY x WAVELENGTH
Explanation
FREQUENCY x WAVELENGTH
Each Harmonic has a different frequency and wavelength
Frequency x Wavelength gives the same answer for ALL Harmonics
Cycles/Seconds x Meters/Cycle= Meters/Second which is a value for speed of the Wave on the string
If Frequency increases, Wavelength decreases and if Frequency decreases, Wavelength increases
These concepts of Frequency and Wavelength and their relationship are basic building blocks of the study of wave properties and behavior. The mathematical formula for speed = frequency x wavelength .

21. Sound Waves Explanation How do we perceive Sound Waves?
What do they have in common with other kinds of waves?
What is different about Sound Waves?
We use our sense of hearing to perceive sound waves, but when there are very loud, low pitched sounds we can “feel” them.
Sound has frequency, wavelength, speed and resonance in common with other kinds of waves we have studied. Pretty much all the same characteristics as the wave on the string.
Sound waves are different in that they are longitudinal waves. Think about a speaker, how does it work? By looking at the cone of the speaker it is obvious that it moves back and forth. As it moves forward it compresses the air and as it moves back it expands the air. This causes a pressure wave to travel away from the speaker. When this pressure wave hits us our skin doesn’t usually feel it, but our eardrum which is extremely sensitive to this kind of occurrence is. These little waves cause it to move back and forth at a certain frequency, and we interpret these vibrations as sounds.

22. Sound and Music - Chords
Explanation
Sound and Music - Chords
Different notes have different frequencies.
Chords are combinations of different notes with specific mathematical relationships.
Different relationships of the notes will produce chords with very different “moods” or “feel.”
These points are basic to the understanding of the relationship between frequency, notes, chords, and music. Musical arrangements have mathematical relationships.

23. Musical Instruments Explanation
Musical instruments play different notes
Frequencies are controlled by altering wavelength
Vibrating materials like strings or reeds cause chunks or columns of air to vibrate
What makes two notes sound different? They are different frequencies.
What makes the notes happen on a guitar? A string is plucked, causing it to vibrate which sends sound waves to our ears.
Since the speed of sound in air is constant, if you raise the frequency of a note, what happens to the wavelength? It gets shorter.
Stringed instruments use the length of the string that is allowed to vibrate, which controls what frequency produced, which determines the note that the instrument produces. What causes the air to vibrate in horns? In woodwind, it is the reed that vibrates. In brass horns it is the musician’s lips.
No matter what is causing the air to vibrate, what determines the note that is played? Frequency.
These instruments use columns of vibrating air. If the guitar controlled the frequency by changing the length of the string, what do you think controls the frequency of the note being played by the horn? Changing the length of the column of air.
How could this be done? Let’s think about a trombone. The length of the column can be controlled by extending or retracting the slide tube of a trombone. The air is vibrating inside there, and if the length is changed, the frequency would change, much like the string. Longer=lower, shorter=higher
Trumpet- valves are used to connect tubes to extend the column
Flute- opens and closes holes to control where nodes and anti-nodes on the vibrating column of are are located and thusly controlling the wavelength and frequency.

24. Musical Instruments Explanation
Natural Frequencies/Harmonics cause amplification through Resonance
Instruments can be amplified this way and/or electronically
The vibrating element vibrates at ALL its Harmonics, not just the Fundamental.
The combination of these frequencies give an instrument its particular sound.
What structural difference do you see between acoustic and electric guitars? Electric guitars usually have a solid body while acoustics have a hollow body and at least one sound hole.
We know that the vibrating string makes the sound, but why is the acoustic so much louder than the electric if the electric is not plugged into an amp? The electric gets louder from the electronic amplification of the amp. The acoustic uses the air inside the hollow body as an amplifier. The chunk of air inside the body resonates.
It turns out that the string, the column of air, your vocal cords, all of them, vibrate at their Fundamental, but also at all of their harmonics. The dominant tone is the Fundamental, which accounts for about 50% of what goes into the overall note. The Second harmonic about 25%, the Third 15% and so on. These percentages are different for different materials AND shapes of materials,which is why even though a trumpet and trombone are made of the same material, the shapes of the air columns they use are different and therefore have a different quality. It is this quality that is each instrument’s signature or fingerprint, and also how computerized voice recognition works. Since everyone’s vocal cords are slightly different, our voices have unique imprints and a computer can recognize a particular person’s distinctive voice frequency pattern. Electronic devices can be isolate the different harmonic frequencies and manipulate them. This is essentially what a distortion pedal for an electric guitar does.

25. Elaboration Speed of sound in air at room temperature = 350 m/s.
Important numbers:
Speed of sound in air at room temperature = 350 m/s.
Speed of light in a vacuum (in outer space) = 299,792,458 m/s or 3.0 x 108

26. Frequency calculations
Velocity of a sound wave is equal to its frequency times its wavelength.
v = f x λ
3. So…if you divide 350m/s by a tube's wavelength value, you obtain the approximate frequency in cycle per second, or hertz, of the note the tube will produce.
1. wavelength can be obtained by multiplying the tube length in meters by 4
Example:
350 m/s
tube length of 21 cm (.21 m) x 4= .84 m
2. velocity is 350m/s in normal room air temperature
You can calculate the approximate frequency of sound that any length of pipe will produce. The velocity of a sound wave is equal to its frequency times its wavelength. Put another way, frequency equals the velocity divided by wavelength. The velocity is 350m/s in normal room air temperature. The wavelength can be obtained by multiplying the tube length in meters by 4 (the number of transits). Therefore, if you divide 350m/s by a tube's wavelength value, you obtain the approximate frequency in cycle per second, or hertz, of the note the tube will produce.
These numbers will be not be accurate but will be within reasonable % error due to the following:
The diameter of the tube affects the frequency, also. The reflection of the sound wave doesn't occur exactly at the open end of a tube but happens at a point slightly beyond the end. The larger the diameter of the pipe, the farther from the end the reflection occurs. To more accurately estimate the value for the frequency, add .03 of the inside diameter to the length of the tube.
= frequency of 416 Hz

27. Frequency calculations:
Now calculate the frequency of the Palm Pipes assigned to the members of your group and be prepared to share your answers with the class.

28. Approximate answers: Note Length (cm) Frequency (Hz) F1 23.6 349 G1
23.6
349 G1
21.0
392 A1
18.7
440
B flat 1
17.5
446 C1
15.8
523 D1
14.0
587 E1
12.5
659 F2
11.8
698 G2
10.5
784 A2
9.4
880
B flat 2
9.2
892 C2
7.9
1046 D2
7.0
1174 E2
6.2
1318 F3
5.9
1397
These numbers will be not be accurate but will be within reasonable % error due to the following:
The diameter of the tube affects the frequency, also. The reflection of the sound wave doesn't occur exactly at the open end of a tube but happens at a point slightly beyond the end. The larger the diameter of the pipe, the farther from the end the reflection occurs. To more accurately estimate the value for the frequency, add .03 of the inside diameter to the length of the tube.

29. Closure
In your notes, write a brief summary of what you have learned.