How Did You Diddley- Do That?
In our second unit of light, sound, and time, we looked at an array of different ways to calculate the different wavelengths, frequencies, and amplitudes of sound waves. That of course wasn't all that was presented in the unit there were also lessons on how fast sound travels through different mediums and the structure of our ears to take a look at how we're able to hear everything we do daily. Our Action Project took us in a different direction though and tasked us with making our own sound through an instrument called a diddley bow. This is a guide to making your first functional diddley bow.
What this project called for was a wood plank, guitar string, battery (although anything with the same width would do), screws, and metal can. It was a bit strange when we were tasked to bring a can and battery into class but once we got started to construct it all it made a lot more sense. The string has to be made sure that it's tied around each screw on either end really well or you won't get you're desired sound. Then was to secure the can in place puncturing a hole through the end with a lid still on directly in the middle. Slide it all the way down and screw it tight as you can and then you can move onto the head of the instrument. The battery´s a bit more strenuous, you have to make sure the string on the other side is the absolute tightest it can be, then back the battery up into the string and test for where you think a good sound comes from. Then, as close to that as you can screw it into place. make sure it's secure on both sides so it doesn't fly off. The last thing to do is measure how far it is from the start of the battery to the punctured side of the can. These markings are going to represent your fretts so mark the halfway point, one-third and two-thirds of the way, and one-fourth and three-fourths of the way.
Below is my finished product:
Next was to measure the space between the plank and string that creates a trapezoid. I measured both of the sides to be 1.5 inches to the center point of the can and 1.1 inches to the top of the battery. The length of the board between the two is 19 inches so now all we gotta do is find the side on the top the string is representative of. The strategy I used was to cut the trapezoid into a rectangle and triangle. To find our missing piece (now the hypotenuse) we´d have to add b2-b1which is 0.4 squared plus 19 squared and then square the answer to getting the approximate answer of 19.004 for the top side of the trapezoid. So now with all sides, we can find the area of our trapezoid which is 53.2 inches. The unfound angles of the trapezoid are 114.7 for the lower angle and 65.3 for the upper angle.
That's not all that's needed for our diddley bow calculations though. The body of the one-stringed guitar is a cylinder with a radius of 1.5 inches and a height of 4.5 inches the volume can be determined with the equation pi r^2 h. The volume came out to be 31.81 inches.
The diddley bow you´ve created should be able to produce some sound if the steps have been executed correctly. By the fretts marked I was able to determine the frequency and wavelength of all of them using an online tuner. All harmonics are listed below:
As the last step of the process I tried out my diddleybow to see what it sounded like:
This project was one that I thought was a bit out of the ordinary for what is usually to be expected and that's what I like about it. Making music of any kind is something I really enjoy and it was fun having the opportunity to express myself in that way. The math was a challenge for sure but it all came together I think quite nicely in the end. The most challenging part I´d have to say was putting the strings onto the instrument.
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