Strings, Music Makers
Though the primary sound of an acoustic guitar is produced by vibrations from the soundboard (top), something has to set that wood oscillating. And, of course, since the wood is a fixed shape and material it can inherently only produce one basic sound. The infinite variety of guitar music is the product of its strings.
Strings run from the bridge, over the saddle, across the body, up the neck, through the nut and around the tuning pegs. Along that road a great many things happen to strings on the way.
At the bridge, strings are tied or (more commonly today) have a small knob to secure them. As they travel over the saddle, a solid place is formed that allows the formation of one of two critical ’stationary points’. The other point is at the nut, where small grooves keep the strings nearly parallel and provide another stationary point.
Those two points make it possible for a string to vibrate in what are called standing waves. Imagine a jump rope with a girl at each end. One of them waves the rope and it moves up and down in a familiar pattern. She then gives it a flip and it forms a node (another stationary point) in the middle. Complicate that pattern and you approach what happens when a guitar string vibrates.
The starting point is the base frequency of the string, determined by its thickness, material and tension. Lower strings are usually formed by winding a tight coil around nylon, another metal or a composite. Higher strings are a single wire. It isn’t always the case that the lower string is wound, for example - think of a 12-string guitar.
Add to that complexity the possibility of changing the length of the string, by clamping it down against the fretboard. Changing the length obviously changes the pitch, producing the wide variety of notes of your favorite riff. Or, you can change that tension by turning the tuning pegs, which are designed to keep them from slipping.
But that’s just a basic guitar today of one type. Throughout history, and in the varied guitar market of the contemporary world, there are dozens of variations.
Where a lute leaves off and a guitar begins is a matter for historians. But at some point, one became much like the other as it evolved from four strings to six. Different countries tried their own variations around the same period. Some tried seven strings, others eight or nine or even ten. These variations still exist around the world today.
In the modern world there are similar variations, such as the well-known 12-string, a six-string arrangement doubled in pairs called ‘courses’. Baroque guitars were also paired, for example, but with only four or five courses rather than six.
Whether nylon or steel, E-string or G, four or twelve, they all have one purpose: to vibrate the bridge and saddle, which vibrates the soundboard. That resonance is transferred to a cavity and out comes: Music.