Acoustic and Acoustic Electric 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. The original, general term for this stringed instrument is guitar, and the retronym 'acoustic guitar' 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.

Guitar strings may be plucked individually with a pick (plectrum) or fingertip, or strummed to play chords. Plucking a string causes it to vibrate at a fundamental pitch determined by the string's length, mass, and tension. (Overtones are also present, closely related to harmonics of the fundamental pitch.) The string causes the soundboard and the air enclosed by the sound box to vibrate. As these have their own resonances, they amplify some overtones more strongly than others, affecting the timbre of the resulting sound.

An acoustic-electric guitar is an acoustic guitar fitted with a microphone or a magnetic or piezoelectric pickup. They are used in a variety of music genres where the sound of an acoustic guitar is desired but more volume is required, especially during live performances. The design is distinct from a semi-acoustic guitar, which is an electric guitar with the addition of sound chambers within the guitar body.

Usually, acoustic-electric guitars are fitted with piezoelectric pickups, requiring a preamplifier incorporated into the guitar body to amplify the signal before it travels to the main guitar amplifier. These preamps may also come with an integrated tuner and tone controls of varying types; equalizers with up to six frequency bands may be used.