The Physics of an Acoustic Guitar

Guitar Picture  
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    An acoustic guitar is one of the most popular instruments used in music. The concept of how it works is basically when a string is plucked it vibrates the body which resonates the air inside of the guitar and produces a larger sound. The type of strings and the body of the guitar all have different effects on what kinds of sounds are produced. The body of the guitar is usually a light, springy wood such as spruce about 2.5 mm thick. The most common strings used in acoustic guitars are nylon strings (classical) and steel strings.
    On normal acoustic guitars there are six strings. From top to bottom the strings are E, A, D, G, B, and E that each correspond to the frequencies of 82.4, 110.0, 146.8, 196.0, 246.9, and 329.6 (howstuffworks). Each frequency produces a different sound where the smaller the frequency is the lower the sound is. It is impossible to get the same exact sound out of two guitars, or even make the same sound twice from the same guitar because the tension in the strings are constantly changing when there are forces from plucking.
    The strings vibrate the body which then vibrates the air inside of it. The body needs a relatively large surface area so it can move the air backwards and forwards. The air inside resonates causing the air at the sound hole to oscillate and producing sound. Here you can look further into the different parts of how the guitar works: Strings, Body, and Air.


Mark Roseberry
Physics 211 FE3