The Science Behind the Diddley Bow

Welcome back to my blog. In my most recent STEAM course, I have been taking a class called Light, Sound, and Time. In this most recent unit, Sound, I have been learning all about sound, what it means and how we hear sounds and sound waves.
We also looked at a concept called the Doppler effect. The Doppler effect refers to the phenomenon of sounds changing in frequency and pitch when moving closer or farther from the observer. When a sound moves closer to the observer, it increases in frequency and pitch whereas when a sound is moving away from the observer, it decreases.

I have, in this class, enjoyed learning about these concepts and with this information I created a project to show what I've learned. For this action project, I have created a diddley bow. A diddley bow is a single stringed guitar that creates sound by putting tension on the string in different places to change the pitch. These sounds are then amplified with, on my diddley bow, a hollow tin can. We can also change the pitch by adding more or less tension to the string.

To make my diddley bow, I started out with a piece of wood plank and attached a tin can to it with a guitar string going through it. I used a marker as my nut to both add more tension and ensure the string does not touch the wood, this would interfere with the sound. I found this project interesting because all of the parts used were recycled and relatively easy to find. 

To demonstrate the Doppler effect on my diddley bow, we can play a note and if we move it around, the sound will change. If you are closer to the diddley bow while its playing a note, it will sound higher.

Below, you will find some different math concepts and how they relate to my project.  

This diagram shows the angle of the string and wood plank.

(Diddley Bow diagram, KH, 2022)

 This diagram shows a more detailed version if my diddley bow along with the area of the trapezoid, which is the shape it creates, and the volume of the resonator or amplifier.

(Diddley Bow diagram, KH, 2022)

Finally, here are a couple images of the diddley bow I created.

(Diddley bow, KH, 2022)

(Diddley bow, KH, 2022)

 

(Diddley bow, KH, 2022)

KAH · Diddley bow recording

 

This is a recording of what my diddley bow sounds like.  

Below, you will find what the harmonics on my diddley bow are.

 

This action project has been my favorite overall this term. I feel that I was able to have a much better understanding of sound and how we can learn from it. This was a great way to apply my learning from my internal investigation.