This is the 2nd unit in the Junior STEAM class, Light, Sound, and Time. The second unit was focused on sound. We learned all about sound and how it can be applied to the real world. We studied how light and sound are related, and how to calculate the distance it takes sound to travel. We learned about things like the Doppler effect and sonic booms, where sounds that are moving have a different pitch, or what happens when something travels faster than sound. We also studied how our ears perceive sound and the human threshold of hearing. We looked at the anatomy of the human ear and studied sound waves and measured them. To prepare for our action project, we went to the Chicago Music Exchange to learn about guitars and other instruments and how they produce sound. We were able to play instruments, and talk to experts about how the different instruments produce sound. For the action project, we made our own guitars or Diddley Bows. This is a one-stringed guitar made out of different household materials. The made the Diddley Bow, and then recorded ourselves playing it, and we drew the harmonics the played. We also calculated the length and angle of the guitar and the volume of the resonator.
The instrument I made is called a Diddley Bow. It is a type of homemade guitar. It is made out of wood, a tin can, batteries, and guitar strings. The diddley bow can be as little as 1 string, or as many as 6. Diddley bows also have varying amounts of detail and features. My Diddley bow was made by using a 2 x 4 piece of wood and measured where I wanted the nut to go. The nut was made by using a dead AA battery. I then used a tin can as the body or the resonator of the Diddley Bow. I poked a hole in it, and then threaded the guitar string from the nut through the resonator and then tied it around the screw at the base of the resonator. I made sure that the string was taught enough to make loud enough sound but that it wasn’t too taught to play.
The Diddley Bow produces sound by vibrating the string. The string’s vibrations are amplified by the resonator or the body which is made out of a tin can. The pitch can be changed by tightening or loosening the screw that the string is attached to, like a tuning peg. Or shortening the length of the string. The volume can be changed by how hard the string is plucked. This changed the amplitude of the wave that the string makes, producing a louder sound. The width of my string is 0.05 in.
My Diddley Bow demonstrates wavelength and frequency by manipulating the strings. When the strings are plucked, a standing wave is produced. This is how sound is portrayed in waveform. The longer the wavelength, the lower the frequency and vice versa. Pitch is how our ears perceive frequency, the higher the frequency of a wave, the higher pitch it will sound. If the string is plucked and produces a high-frequency wave, a higher pitch sound will be created. If the wave has a lower frequency, it will produce a lower pitch sound. This is how the Diddley bow is played so it can produce different pitches.
Here is a recording of me playing the Diddley Bow The side view of the guitar created a trapezoid with an area 15 x (1.5 + 1.75) / 2 = 1.625 x 15 = 24.375 sq in. I figured out how to find the angles by dividing the trapezoid into a rectangle with a triangle on top, with a base of 15 and a height of .25 and a hypotenuse of 15.5. To find the upper right angle, I calculate tan -1 (15 / .25) = 89 degrees. The left angle of the triangle is 1 degree because 89 + 90 = 179 which is 1 short of 180 degrees. This means the left angle of the trapezoid is 91 degrees because 1 + 90 = 91.
The tin can I used as a resonator has a radius of 1.75 in. To calculate volume, we need to know the area of the circle and the height. The area of my circle is π 1.75 ^2 = 9.62 cubic in. The height is 4.5 in so the volume is 4.5 x 9.62 = 43.29 cubic in
My Diddley Bow plays 4 harmonics. I found the frequency of my Diddley Bow which was 55.2 Hz (Hertz) I then found the wavelength. The speed of sound is 343 m/s so 55.2 Hz / 343 m/s = 6.21 meters which is my wavelength. As Frequency gets larger, the wavelength gets smaller.
The 1st harmonic represents the open note.
The 2nd harmonic represents the ½
The 3rd harmonic represents the ⅓ and ⅔
The 4th harmonic represents the ¼ and ¾
Frequency = 55.2 Hz Wavelenth = 6.21 meters
Frequency x 2 = 110.4 Hz Wavelength / 2 = 3.105 meters
Frequency x 3 = 165.6 Hz Wavelength / 3 = 2.07 meters
Frequency x 4 = 220.8 Hz Wavelength / 4 = 1.5525 meters
In conclusion, I liked this project. I thought it was an interesting hands-on way to learn about sound and sound waves. I enjoyed making the Diddley Bow as well as calculating it. This was a challenging project as I had a lot of other things going on, but I am proud of how the Diddley Bow actually came in the end.
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| CM "Diddley Bow" (2019) |
The Diddley Bow produces sound by vibrating the string. The string’s vibrations are amplified by the resonator or the body which is made out of a tin can. The pitch can be changed by tightening or loosening the screw that the string is attached to, like a tuning peg. Or shortening the length of the string. The volume can be changed by how hard the string is plucked. This changed the amplitude of the wave that the string makes, producing a louder sound. The width of my string is 0.05 in.
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| CM "Diagram" (2019) |
My Diddley Bow demonstrates wavelength and frequency by manipulating the strings. When the strings are plucked, a standing wave is produced. This is how sound is portrayed in waveform. The longer the wavelength, the lower the frequency and vice versa. Pitch is how our ears perceive frequency, the higher the frequency of a wave, the higher pitch it will sound. If the string is plucked and produces a high-frequency wave, a higher pitch sound will be created. If the wave has a lower frequency, it will produce a lower pitch sound. This is how the Diddley bow is played so it can produce different pitches.
Here is a recording of me playing the Diddley Bow The side view of the guitar created a trapezoid with an area 15 x (1.5 + 1.75) / 2 = 1.625 x 15 = 24.375 sq in. I figured out how to find the angles by dividing the trapezoid into a rectangle with a triangle on top, with a base of 15 and a height of .25 and a hypotenuse of 15.5. To find the upper right angle, I calculate tan -1 (15 / .25) = 89 degrees. The left angle of the triangle is 1 degree because 89 + 90 = 179 which is 1 short of 180 degrees. This means the left angle of the trapezoid is 91 degrees because 1 + 90 = 91.
 |
| CM "Trapezoid" (2019) |
The tin can I used as a resonator has a radius of 1.75 in. To calculate volume, we need to know the area of the circle and the height. The area of my circle is π 1.75 ^2 = 9.62 cubic in. The height is 4.5 in so the volume is 4.5 x 9.62 = 43.29 cubic in
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| CM "Resonator" (2019) |
My Diddley Bow plays 4 harmonics. I found the frequency of my Diddley Bow which was 55.2 Hz (Hertz) I then found the wavelength. The speed of sound is 343 m/s so 55.2 Hz / 343 m/s = 6.21 meters which is my wavelength. As Frequency gets larger, the wavelength gets smaller.
The 1st harmonic represents the open note.
The 2nd harmonic represents the ½
The 3rd harmonic represents the ⅓ and ⅔
The 4th harmonic represents the ¼ and ¾
Frequency = 55.2 Hz Wavelenth = 6.21 meters
Frequency x 2 = 110.4 Hz Wavelength / 2 = 3.105 meters
Frequency x 3 = 165.6 Hz Wavelength / 3 = 2.07 meters
Frequency x 4 = 220.8 Hz Wavelength / 4 = 1.5525 meters
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| CM "Harmonics" (2019) |
In conclusion, I liked this project. I thought it was an interesting hands-on way to learn about sound and sound waves. I enjoyed making the Diddley Bow as well as calculating it. This was a challenging project as I had a lot of other things going on, but I am proud of how the Diddley Bow actually came in the end.
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