甘比英文拓展写作-The physics of playing guitar-zln_九月

Day 19 The physics of playing guitar

Have you ever shouted and cheered for the performance of guitarists like Jimi Hendrix? But do you know the physics of playing guitar and the secret of music?

A normal guitar has six stretched strings fixed between the head and the bridge. Another main part is a wooden box as a resonant tank with a hole in its body. Simply, the secret of creating the notes lies in the strings and the music comes from some sound waves. When you pluck a guitar string, you create a vibration called a standing wave. Some points on the string, called nodes, don’t move at all, while other points, anti-nodes, oscillate back and forth. The vibration that is transferred to the wood body jostles the surrounding air into sound waves, which are then translated into electrical impulses that your brain interprets as sound. The pitch of that sound depends on the frequency of the compressions. High frequency that is created by a quick vibration makes a high-pitched sound, and a slow vibration produces a low-pitched sound. Four things affect the frequency of a vibrating string: the length, the tension, the density and the thickness. For typical guitars, the length and the tension of strings are similar and there are many differences in thickness and density. Thicker strings vibrate more slowly, producing lower notes. Hence the variety of thickness and density make a group of different notes.

The frets are also important parts in a guitar. They are corresponded to half steps whose frequency is each 2^(1/12) higher than the one before in an octave. With the hints of frets, you can find the position where your fingers should press on and produce the desired notes. Playing two or more strings at the same time allows you to create new wave patterns like chords and other sound effects. Then you can understand the moment when you enjoy the harmonious beats of melodies.

2017.2.8