An electric guitar is a guitar that requires external amplification in order to be heard at typical performance volumes, unlike a standard acoustic guitar. It uses one or more pickups to convert the vibration of its strings into electrical signals, which ultimately are reproduced as sound by loudspeakers. The sound is sometimes shaped or electronically altered to achieve different timbres or tonal qualities from that of an acoustic guitar via amplifier settings or knobs on the guitar. Often, this is done through the use of effects such as reverb, distortion and "overdrive"; the latter is considered to be a key element of electric blues guitar music and jazz, rock and heavy-metal guitar-playing. Designs also exist combining attributes of the electric and acoustic guitars: the semi-acoustic and acoustic-electric guitars.
In physics, acoustics, and telecommunications, a harmonic is a sinusoidal wave with a frequency that is a positive integer multiple of the fundamental frequency of a periodic signal. The fundamental frequency is also called the 1st harmonic; the other harmonics are known as higher harmonics. As all harmonics are periodic at the fundamental frequency, the sum of harmonics is also periodic at that frequency. The set of harmonics forms a harmonic series.
An overtone is any resonant frequency above the fundamental frequency of a sound. In other words, overtones are all pitches higher than the lowest pitch within an individual sound; the fundamental is the lowest pitch. While the fundamental is usually heard most prominently, overtones are actually present in any pitch except a true sine wave. The relative volume or amplitude of various overtone partials is one of the key identifying features of timbre, or the individual characteristic of a sound.
In musical instrument classification, string instruments or chordophones, are musical instruments that produce sound from vibrating strings when a performer plays or sounds the strings in some manner.
A fret is any of the thin strips of material, usually metal wire, inserted laterally at specific positions along the neck or fretboard of a stringed instrument. Frets usually extend across the full width of the neck. On some historical instruments and non-European instruments, frets are made of pieces of string tied around the neck.
In music, inharmonicity is the degree to which the frequencies of overtones depart from whole multiples of the fundamental frequency.
In music, extended technique is unconventional, unorthodox, or non-traditional methods of singing or of playing musical instruments employed to obtain unusual sounds or timbres.
Sympathetic strings or resonance strings are auxiliary strings found on many Indian musical instruments, as well as some Western Baroque instruments and a variety of folk instruments. They are typically not played directly by the performer, only indirectly through the tones that are played on the main strings, based on the principle of sympathetic resonance. The resonance is most often heard when the fundamental frequency of the string is in unison or an octave lower or higher than the catalyst note, although it can occur for other intervals, such as a fifth, with less effect.
A prepared guitar is a guitar that has had its timbre altered by placing various objects on or between the instrument's strings, including other extended techniques. This practice is sometimes called tabletop guitar, because many prepared guitarists do not hold the instrument in the usual manner, but instead place the guitar on a table to manipulate it.
A vibrato system on a guitar is a mechanical device used to temporarily change the pitch of the strings. They add vibrato to the sound by changing the tension of the strings, typically at the bridge or tailpiece of an electric guitar using a controlling lever, which is alternately referred to as a whammy bar, vibrato bar, or incorrectly as a tremolo arm. The lever enables the player to quickly and temporarily vary the tension and sometimes length of the strings, changing the pitch to create a vibrato, portamento, or pitch bend effect. Instruments without a vibrato have other bridge and tailpiece systems.
A multiphonic is an extended technique on a monophonic musical instrument in which several notes are produced at once. This includes wind, reed, and brass instruments, as well as the human voice. Multiphonic-like sounds on string instruments, both bowed and hammered, have also been called multiphonics, for lack of better terminology and scarcity of research.
The following outline is provided as an overview of and topical guide to guitars:
An acoustic guitar is a musical instrument in the string family. When a string is plucked, its vibration is transmitted from the bridge, resonating throughout the top of the guitar. It is also transmitted to the side and back of the instrument, resonating through the air in the body, and producing sound from the sound hole. While the original, general term for this stringed instrument is guitar, the retronym 'acoustic guitar' – often used incorrectly to indicate the steel stringed model – distinguishes it from an electric guitar, which relies on electronic amplification. Typically, a guitar's body is a sound box, of which the top side serves as a sound board that enhances the vibration sounds of the strings. In standard tuning the guitar's six strings are tuned (low to high) E2 A2 D3 G3 B3 E4.
In music, the undertone series or subharmonic series is a sequence of notes that results from inverting the intervals of the overtone series. While overtones naturally occur with the physical production of music on instruments, undertones must be produced in unusual ways. While the overtone series is based upon arithmetic multiplication of frequencies, resulting in a harmonic series, the undertone series is based on arithmetic division.
An experimental musical instrument is a musical instrument that modifies or extends an existing instrument or class of instruments, or defines or creates a new class of instrument. Some are created through simple modifications, such as cracked cymbals or metal objects inserted between piano strings in a prepared piano. Some experimental instruments are created from household items like a homemade mute for brass instruments such as bathtub plugs. Other experimental instruments are created from electronic spare parts, or by mixing acoustic instruments with electric components.
Playing a string harmonic is a string instrument technique that uses the nodes of natural harmonics of a musical string to isolate overtones. Playing string harmonics produces high pitched tones, often compared in timbre to a whistle or flute. Overtones can be isolated "by lightly touching the string with the finger instead of pressing it down" against the fingerboard. For some instruments this is a fundamental technique, such as the Chinese guqin, where it is known as fan yin, and the Vietnamese đàn bầu.
The Moodswinger is a twelve-string electric zither with an additional third bridge designed by Yuri Landman. The rod which functions as the third bridge divides the strings into two sections to cause an overtone multiphonic sound. One of the copies of the instrument is part of the collection of the Musical Instrument Museum in Phoenix, Arizona.
Sympathetic resonance or sympathetic vibration is a harmonic phenomenon wherein a passive string or vibratory body responds to external vibrations to which it has a harmonic likeness. The classic example is demonstrated with two similarly-tuned tuning forks. When one fork is struck and held near the other, vibrations are induced in the unstruck fork, even though there is no physical contact between them. In similar fashion, strings will respond to the vibrations of a tuning fork when sufficient harmonic relations exist between them. The effect is most noticeable when the two bodies are tuned in unison or an octave apart, as there is the greatest similarity in vibrational frequency. Sympathetic resonance is an example of injection locking occurring between coupled oscillators, in this case coupled through vibrating air. In musical instruments, sympathetic resonance can produce both desirable and undesirable effects.
String instruments are capable of producing a variety of extended technique sounds. These alternative playing techniques have been used extensively since the 20th century. Particularly famous examples of string instrument extended technique can be found in the music of Krzysztof Penderecki, Witold Lutosławski, George Crumb, and Helmut Lachenmann.
A bridge is a device that supports the strings on a stringed musical instrument and transmits the vibration of those strings to another structural component of the instrument—typically a soundboard, such as the top of a guitar or violin—which transfers the sound to the surrounding air. Depending on the instrument, the bridge may be made of carved wood, metal or other materials. The bridge supports the strings and holds them over the body of the instrument under tension.
![Different possible shapes of a third bridge: "a common six-sided pencil [4mm contact], a round dowel [more focused contact], and an L-shaped bracket [even more fine]." The pencil creates, "a damping effect and also prevents energy from transferring across the bridge to the opposing string segment," with the dowel, "resulting in greater sustain and cross-string resonance," and the bracket, "offers even more sustain than a [round] dowel." 3rd bridge bridge shape comparison.svg](http://upload.wikimedia.org/wikipedia/commons/thumb/6/65/3rd_bridge_bridge_shape_comparison.svg/220px-3rd_bridge_bridge_shape_comparison.svg.png)
