Musical Instrument Blog #1: Natalie Sanchez_Earth Stream

Natalie Sanchez

5/19/11
Blog #1

I am planning on building a guitar for my physics project. A guitar is played by plucking or strumming its strings. In order to change the note of a guitar, you must place your fingers on different strings of different frets on the fret board of the guitar. A (acoustic) guitar's body is shaped like a very wide "8" with a hole in the middle of it. I think that the a guitar creates sound because the sound waves that are produced when you pluck or strum its strings bounce into its sound hole and then re-bounce  out of the guitar to produce external sound. The guitar changes notes when you hold certain strings at certain points because the strings becomes more tense and produces a higher note than it would if you just play the string on its own. Maybe this also has to do with sound in that the sound wave is weaker than sound wave of a single chord so it sounds different when it rebounds out of the guitar. It could also just be that the string with pressure on the fret has a higher note than the string without pressure on the fret, and therefore just sounds the way that it does normally, only louder because of the sound hole. I like to connect sounds waves to ocean waves because they move in a very similar manner. The wave travels straight through said path and does not stop. The same thing happens with a sound wave. The wave is caused by an initial disturbance (as explained the in the beginning of the today's experiment) and then continues to travel throughout the path is started on. The sound waves in this case are created by the strings, go into the sound hole of the guitar, and then bounce back out of the guitar once they hit the back board of the body of the guitar, much like ocean waves do when they hit rocks; they bounce bounce back into the ocean. 
Links to guitar picture:
http://stringsattached.info/?p=463
link to guitar player:
http://www.youtube.com/watch?v=Lcmb4RplClQ

5/26/11:
Blog #2

1. How is sound produced by this instrument (now that you know more about sound, please try to refer specifically to the energy transfer and vibrations)?

My instrument (guitar) produces sound through its strings. The thiner the string, the higher pitch it will have, and the more the string is stretched, the higher its pitch. The thicker the string, the lower its pitch and the less it is stretched the lower its pitch. When it vibrates (the strings), it throws sound waves through the sound hole, which hit the back of the guitar, and then travel back out because it has a set boundary. 

2. Based on your understanding, how are you changing the pitch? What physical characteristics are important in this instrument?

The pitch changes according how thin/stretched the string is. The thinner/more stretched the string is, the higher the pitch and visa versa. The most important physical characteristics on the guitar is the sound hole, and the strings. 

3. What materials will you actually be using for your instrument and why? How will you play your instrument? What is your plan for constructing the instrument? 

I will be using a cigar box, wood, a wood cutter, cote hangers, guitar strings, smaller planks of wood, and tunners. These objects will serve as my body, strings, sound hole, and tunner for my guitar. I already know how to play guitar. I will play the guitar by strumming/plucking it according to the guitar chords that I have printed out. I am planning to buy the parts that I have mentioned and build the instrument at home. 

4. What outstanding questions do you still have?

How does what we learn in class have to do with a guitar?
Am I right about how sound travels from a guitar? please correct me if I am wrong. 
How can I measure the sound weaves coming out of my guitar?