In my class Light, Sound, and Time we have been learning about wavelengths, frequency, guitars, speed of sound, etc. We went to Guitar Center to look at the different instruments like acoustic guitars, electric guitars, drums, and even amps. Taking all this information we decided to build a one string guitar called a Diddley bow. We used a tin can, wood, screws, guitar string, and a battery or in my case a glue stick.
On the left is my sketch of my Diddley bow, I also labeled the different parts and what they are meant to be. I have also included a video of myself playing the Diddley bow below.
EM, 2022
EM, 2022
On the left I put a picture of the location of the first four harmonics on my didldley bow. I know you may be wondering how this piece of wood is producing this sound. Well when you use the diddley bow, the sound goes through the tin can and comes out louder. Also I realized that when you move the glue stick it changes the pitch. Depending on how tight or loose you tied your guitar string it also changes the sound.
EM, 2022
My diddley bow demonstrates the key science principles like wavelength, sound waves, frequency, and amplitude. If you didn't know wavelength is the distance in the line of advance of a wave from any one point to the next point. I had to find the wavelength of my harmonics for my diddley bow. Sound waves are waves that results from the back and forth vibration of the particles of the medium through. There are two main sound waves, transverse and longitudinal waves. A transverse wave is a wave in which the vibrating element moves in a direction perpendicular to the direction of advance of the wave. A longitudinal wave is a wave in which the particles of the medium vibrate in the direction of the line of advance of the wave. So basically if you were to take a slinky and push it forward that would make a longitudinal wave and if you move it up and let it go down that would be a transverse wave. There is also frequency which describes the number of waves that pass a fixed place in a given amount of time which I also found for my diddley bow. Finally, we have amplitude which is the maximum displacement or distance moved by a point on a vibrating body.
To the left I have my measurements for my string, tin can, volume, area, and hypotenuse of my Diddley bow. For my measurements I measured the height from the wood to the top of my glue stick and I called that "b1". I then measured the height from the wood to the hole in my can and I called that "b2". Finally for this part I measured the width of my wood from the glue stick to the front of the can and called that "h". I used an online tuner to find out my frequency which was 530 Hertz. I also measured my cylinder tin can. I found the height which was 4.5 in and the radius which was 1.6 in. I found the area by using the formula Area= 1/2(b1 + b2) h and got an area of 21.92. I was also able to find the volume by using the formula V= 3.14r^2h and got a volume of about 36.19. I found my hypotenuse by using the Pythagorean theorem. I found the slanted side of my trapezoid (the string) and imagined it as a triangle on top of a rectangle. I used the formula A2+B2=C2 and got 315.76 once I plugged in my numbers and then you find the square root and that gave me an answer of 17.7 for my hypotenuse. Lastly, I found my upper and lower angle.
EM, 2022
After doing all the calculations the final thing to do was find the first four harmonics wavelength and frequency which is what you see on the left. To get the frequency I took my first open note frequency and multiplied it by two to get the second one and then multiplied that number by 3 to get the third one and so on. To get the wavelength I divided the frequency of each harmonic by the speed of sound which is 343m/s.
EM, 2022
In conclusion, I really enjoyed this project. I would 100 percent recommend making. Diddley bow. It was fun and easy, you could use items that you most likely have laying around your house. Something I would do differently would probably be to use a thicker string because mine broke because I tightened it too much and I feel like if I used a thicker string that wouldn't happen. Also looking at my peers diddley bows I feel like those who had thicker string had a better sound. If I did this again I would want to try and do more than one string. Overall, I think everyone should try making their own Diddley bow if they can.
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