amplification
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The process of increasing the strength of a musical signal, making it louder.
Amplification is the electronic boosting of a sound signal so it can be heard at greater volume. In music, amplification transformed performance by allowing small ensembles to fill large venues and enabling quiet instruments to balance against louder ones. An electric guitar sends its signal through an amplifier (amp) that increases the signal strength before sending it to a speaker. Keyboard instruments, bass guitar, and vocals all require amplification for live performance in most popular music contexts. A PA (public address) system amplifies the entire band for the audience. Amplification also enables effects processing: distortion, overdrive, and fuzz are all forms of deliberate over-amplification. In contrast, acoustic instruments in classical music rely on the natural acoustics of the concert hall rather than electronic amplification.
Leo Fender, who designed some of the most iconic guitar amplifiers ever made, could not actually play the guitar himself.