Amplification is a process in which the energy of a sound or an audio signal is increased. It may be accomplished by means of an electronic amplifier or an acoustic resonator, such as the sound box of a musical instrument. Attaching (i.e. coupling) a vibrating object to another surface, such as a soundboard, wall, or floor, will result in a more efficient transfer of energy, and hence this process may also be termed amplification.

Amplification or gain may be measured in decibels.