Sound through Tea and String

Welcome to another blog post for my course, Light Sound and Time. This unit has been based around the study of sound, how we use it, and how people experience sound differently. Sounds are waves that spread certain distances. Throughout the unit we’ve learned about the different ways that sound behaves by understanding its waves and how they work. We also learned about the spectrum of some sounds and how they are measured. This led us to visit the Chicago Hearing Society (CHS) to understand how some people might live without hearing. Also we learned how sign language can allow people to express themselves in new ways. We also went to the Darnton & Hersh Fine Violins store to understand how some string instruments work and why they are built in a particular way.

"Norris D_Bow Back" by john-norris is licensed under CC BY-SA 2.0.

The goal with this action project was to create a diddley bow. For those who may not know, a diddley bow is a one-stringed instrument that can express sounds in certain ways. Some people might not be able to afford certain instruments. Because of this, diddley bows serve as an affordable option. We’re making these for our action projects to understand how we can create devices that can produce sounds on their own. The diddley bow I’m creating is made from a tea tin that wasn’t being used in my house. Instead of throwing it out, I wanted to give it a bigger purpose for this project.

"Diddley Bow Sketch", RBL, 2023

There are many sounds that can be produced through instruments, nature, and even my diddley bow. My diddley bow produces sound by plucking the main string in the middle. When it’s plucked, it produces certain sounds. These sounds are made of pitches that span a certain range from low to high. These pitches have different frequencies, which are the amount of times a sound vibrates over a given period. When playing my diddley bow, the sound produced is either high or low depending on where my diddley bow is plucked. In class, we marked certain distances from the tuner to the resonator to understand how the harmonics form the sound.

Here's my diddley bow recording below:

Blandy · Diddley Bow Recording

Here's each of my harmonics below:

"Diddley Bow Harmonics", RBL, 2023

My diddley bow shows a couple of things that we’ve talked about in class in different ways. For starters, sound waves are produced from it depending on how the string is hit. Sound waves are waves that vibrate over certain distances that can have different harmonics depending on the circumstances. By plucking certain points along my diddley bow, it can produce sounds in different pitches and volumes. I could also move my can from one point to another and that would change the string tensions which changes the frequency of a sound.

Here’s a picture of my diddley bow:

"My Diddley Bow", RBL, 2023

Here are the measurements for my diddley bow:

Can height (B1) - 1.5 in

Can radius (B2) - 1.25 in 

Length of wood (H) - 19 in

Length of vibrating string - 19.0016 in

String thickness - 0.044 in    

And here's how I got the measurements for the distance between the tuner and the resonator:

"Trapezoid and Triangle Calculations", RBL, 2023

Area of trapezoid: 0.5 (1.5 + 1.25) 19 = 26.125 in^2

Cylinder Volume - 3.14 x 1.375^2 x 6 = 35.61 in^3

Trapezoid Angles:

Angle A: 90 Degrees 

Angle B: 90 Degrees

Angle U: Tan^-1 ( 19/0.25) = 89.24 degrees

Angle L: 90 + 90 + 89.35 = 269.35 -> 360 - 269.35 = 90.65 Degrees

The calculations of the trapezoid show the relationship of angles and lengths between the resonator and the tuner. While the triangle shows a smaller part of that shape. This part shows the distance from where the string starts at the resonator, to the string at the bridge. The other side is the resonator to the wood. The last side being when resonator touches the wood to the tuner itself. 

Overall, this project was a fun experience. In class, we don’t often do a lot of hands-on work like building things. This project helped me to understand how and why sound operates. I also didn’t know what a diddley bow was before doing this project. So, this allowed for a new opportunity for me to learn about the instrument. I did find it difficult to get all the measurements for my diddley bow which led to me going back and redoing parts of it. If I were to do this again, I’d want to try using a different type of wood and seeing how that would affect the sound of my future bow. Possibly using a different material or building a different design with the wood itself.