Most people can instantly recognize the sound of a guitar tone. While there are subtle differences between different types of guitars, their basic tonal character is determined by their physical construction and how they are played. The guitar is a stringed musical instrument with a hollow body that amplifies the acoustic vibrations of its strings.
A long, slender neck is attached to the body and is topped by a headstock. Strings are attached to a slightly raised bridge on the body at one end and travel through a hole cut into the body at the other. The strings are connected to a screw-and-gear mechanism in the headstock that controls the tension, or tuning, of the strings on the other end. The size and shape of the body, the length of the neck, and the size of the sound hole are all basic elements of a guitar.
Strings made of “nylon,” or plastic monofilaments, are commonly used on classical and flamenco guitars. The flat-top dreadnaught, the most popular guitar, is usually equipped with “steel” strings, which are steel, nickel, and bronze alloys. The latter produces a louder and brighter guitar tone. The number of strings on a guitar can range from four to eighteen, with six being the most common.
There are several common guitar tunings, but the most common is E above Middle C, followed by B, G, D, A, and E in that order. A string’s length is shortened and its pitch is raised when it is fingered against the guitar’s neck. Multiple strings can be fingered and played simultaneously as many different musical chords in standard tuning. The resulting rhythmic choral sound is a uniquely guitar tone when several, or all, of the strings are struck in musical time — a stroke known as strumming.
Individual strings can also be plucked individually with fingers or a pointed pick to play single notes. This playing method can explain the essence, or sonic waveform, of the guitar tone. The tone has a sharp attack because a string is either struck or not struck, and the string sounds loudest at that moment. It has a strong, oscillating vibrato, which is caused by the length and tension of a guitar’s string. Because the hollow body acts as an echo chamber, it has a long decay.
The timbre, or resonance, of the instrument is more difficult to define, but it is still distinct. It is influenced by two characteristics. To begin with, guitar strings vibrate at multiple secondary harmonic overtones rather than just one. Second, the hollow body’s shape bounces and deforms sound waves in a specific pattern. An electric guitar is fundamentally similar to an acoustic guitar, with the exception that its nearly inaudible tone is electronically picked up, processed, and amplified.