Our challenge for this project was to build three instruments that can play the notes C, D, E, F, G, A, & B. One instrument must use strings, another chimes, and one air movement (wind). The three instruments my group decided to build were a flute, chimes, and a guitar. After constructing the instruments, we had to compose a song to then perform it with the instruments.
Wind
Our PVC flute is able to play seven different notes because vibrating air is forced out in different areas creating different notes. We measured the holes at different lengths to play the notes C, D, E, F, A, and B. The air in the flute vibrates and the energy is radiated as sound and forced out any of the open holes. The energy lost is replaced by the flute player breathing into the larger hole, which goes into the flute. The column of air inside the flute vibrates more easily at some frequencies than others, which determines the playing frequency and pitch. A different combination of covered holes creates a different pitch. The more fingers you place over the holes, the lower the notes will be. The less amount of holes covered, the higher the notes will be. This is because, the air will have to travel further to escape when there are more holes covered. The farther it has to travel, the lower it will sound and the longer wavelength it will have. To find the length of the hole from the mouthpiece we divided the original wavelength of the note by 4 (L = W/4). We knew to divide by 4, because a wind instrument only has ¼ of a whole wavelength. In other words, there are three areas of pressure: high, low, and equilibrium. When you blow into a pipe, your lips create high pressure. Wherever there is a hole, air enters the tube at neutral pressure and neutralizes it to equilibrium. The area from high pressure to equilibrium only makes up a quarter of a wave, so to find the length to the hole, we divide the original note into quarters.
Chimes
The shorter the chime, the higher the natural frequency. Each individual chime is able to play a different note. This is because of the natural frequency of the material, which is determined by the diameter, the length, and the size. Short and narrow chimes create a higher sound than long and wide because they vibrate quicker. Harder materials produce a clearer sounds, because they vibrate faster. Unlike most instruments, the chimes are completely independent of vibrations of the air within the tube. The vibrations travel the length of the tube, producing sound waves. The longer the length of the tube, the lower the natural frequency. Our chimes are short and narrow, so they produce a higher sound. We hung our chimes so they can resonate freely and produce a clear sound. We found the lengths of our chimes by using the ratio 1/(length)2 . We cut and tuned our first chime and then used the ratio to find the other lengths because the frequencies are proportional to the lengths.
String
The strings of the guitar vibrate, and the shape of the guitar itself amplifies the sound so it can be heard. Strings have their own natural frequency, just like our chimes. Instead, the natural frequency is depended on the tension of the string and the length of the string. Once one of the guitar strings is plucked, the string then vibrates, and it produces the natural frequency. The guitar base then causes the sound to become louder. The thickness of the string determines how fast it can vibrate back and forth. A thicker string will vibrate slower, and create a lower pitch than a thinner string. In a traditional guitar, the strings are slightly different thicknesses and lengths with a tuning peg to tune the guitar if it was to become out of tune. For our guitar, we used the same material for the strings, which means that we needed to make the lengths different from each other. We have seven different strings, which are at different lengths and play different notes. The strings are attached to a screw which can be tightened or loosened to tune the instrument. To find the string length, we divided the wavelength of each note in half. This is because when you play a string instrument, you only strum upwards. The string cannot move in two directions at once; it only moves up or down. With only the up OR down motion, we do not get the other half of the wave; we only have half of the wavelength. This is why we divide the original note’s wavelength in half.
Content
Waves: Transfer Energy Transverse Wave: Perpendicular to direction of travel. Can travel through vacuum. Light and electromagnetic spectrum.
Longitudinal Wave: Parallel to medium/direction of travel. Cannot travel through vacuum. Sound.
Wavelength: The distance from crest to crest. Crest: The highest point the medium rises to in a wave. Amplitude: The distance from equilibrium to the crest or trough. Trough: The lowest point the medium sinks to in a wave.
Reflection
Build a band was a fun project. My group and I worked well together and were able to create three solid instruments. One setback my group had was time management/organization. We weren't very organized with who is working on what, and when we should have it finished. We focused on our instruments, which caused us to have little time to work on our instrument summery. One way I could fix this is by communicating when each thing needs to be done, allowing us to have time to work on other things. One thing I can work on personally is leadership. If I take more control and communicate better with my team members, my group and I would have a better time staying organized and on task. One peak of this project was that I was able to do more hands-on work while constructing the instruments. I also did a good job staying on task and accomplishing what needed to be done that day.