Hello! I am a student at GCE lab school and I am in a class called Light, Sound, & Time. In this class, we first learned about light and made pinhole cameras, and then we moved on to learning about sound! In this unit where we have been learning about sound, we talked about sound waves, the speed of sound, the way sound travels through different materials, how speakers work, and more. We even went on a field experience to a violin shop, and talked to the people there about sound, its materials, and crafting violins!
Then we started making our own instruments, called diddley bows! For this project, we needed to use what we learned throughout the unit to create a diddley bow. This project helped us learn about sound, use formulas, and make calculations.
My diddley bow has one bass string, and it is tightened in order to make a vibration when you pluck it. The speed of sound is 343 meters per second, and the vibration is what makes sound waves, that travel to our ears and make us hear the sound. The length of the string is what determines the pitch, which is how high or low the sound is. If you hold down the string by the top of the instrument the pitch won't change much. But the lower you put your hand to hold down the string, it shortens the length of the string, which makes the wavelengths shorter, which makes a higher pitch. This is because speed = wavelength × wave frequency.
Then we started making our own instruments, called diddley bows! For this project, we needed to use what we learned throughout the unit to create a diddley bow. This project helped us learn about sound, use formulas, and make calculations.
My diddley bow has one bass string, and it is tightened in order to make a vibration when you pluck it. The speed of sound is 343 meters per second, and the vibration is what makes sound waves, that travel to our ears and make us hear the sound. The length of the string is what determines the pitch, which is how high or low the sound is. If you hold down the string by the top of the instrument the pitch won't change much. But the lower you put your hand to hold down the string, it shortens the length of the string, which makes the wavelengths shorter, which makes a higher pitch. This is because speed = wavelength × wave frequency.
To make my diddley bow I first needed the body of the instrument. I chose a piece of wood that was on the longer side because I knew I wanted my instrument to have a lower pitch. Then I hammered a nail into the left and right of the wood, to attach the string. Then I attached the string on the left nail and poked a hole in the center of a can and put the string through the hole, moving the can to the left side of the diddley bow. The sound bounces around the can which amplifies the sound. Then I wrapped the other side of the string around the nail on the right and increased the tension by putting a battery in front of that nail.
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| Can, NM, 2023 |
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| Battery, NM, 2023 |
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| 1Diddley bow, NM, 2023 |
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| 2Diddley bow, NM, 2023 |
This took a lot of redoing and retightening, but once it was finished it was time for measurements and calculations. My measurements and calculations:
-1.jpg)
String to wood: 1.5 inches (b2)
Bass string: 31 inches (h)
Height of can: 4.5 inches
Radius of can: 1.4 inches
Diameter of can: 2.8 inches
Volume of can:
Adjacent: b2 - b1 = 0.8
V = top right angle
V = tan^-1 (O/A)
tan^-1(30.5/0.8) = 88.50°
P = top left angle
P = 88.50 + 90 + 90 = 268.5
360 - 268.5 = 91.5°
-2.jpg)
Harmonics:
29.5 ÷ 3 = 9.83
29.5 ÷ 3 × 2 = 19.67
29.5 ÷ 4 = 7.375
7.375 × 2 = 14.75
7.375 × 3 = 22.125
-1.jpg)
Bass string: 31 inches (h)
Height of can: 4.5 inches
Radius of can: 1.4 inches
Diameter of can: 2.8 inches
Battery to wood: 0.7 inches (b1)
Frequency: 160 Hz
Length of wood: 30.5 inches
Thickness of string: 0.046 inches
Volume of can:
V = πr^2 × height
V = 3.14 × 1.4^2 × 4.5
V = 27.69 inches
Area:
Area = ½ (b1 + b2) h
Area = ½ (0.7 + 1.5) 31
Area = 34.1inches
Trapezoid:
Area = ½ (0.7 + 1.5) 31
Area = 34.1inches
Trapezoid:
Adjacent: b2 - b1 = 0.8
V = top right angle
V = tan^-1 (O/A)
tan^-1(30.5/0.8) = 88.50°
P = top left angle
P = 88.50 + 90 + 90 = 268.5
360 - 268.5 = 91.5°
-2.jpg)
29.5 ÷ 3 = 9.83
29.5 ÷ 3 × 2 = 19.67
29.5 ÷ 4 = 7.375
7.375 × 2 = 14.75
7.375 × 3 = 22.125
I think if I did this again I would use a shorter piece of wood for the body of the instrument. I wanted to use a long piece to get a lower pitch so it could be more like a cello since I play the cello. The problem was that I didn't bring a cello string, so I had to put the nails close enough together to fit the bass string. I also could have measured the string I had first, before I hammered nails in the wood. But overall I had a lot of fun with this project!
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