An Exciter is a specialized signal processor that enhances the perceived high-end definition of an audio track by synthesizing new spectral content rather than simply amplifying what is already there. While a standard equalizer acts on existing frequencies, an Exciter analyzes the fundamental tones of the input signal and uses a form of controlled distortion to mathematically generate and add related upper harmonics. This process relies heavily on psychoacoustic principles, tricking the ear into perceiving the sound as louder, closer, and more detailed without significantly raising the electronic peak level of the signal. Historically popularized by the Aphex Aural Exciter, this tool is invaluable for adding a shimmer to dull tracks or repairing audio that has lost its high-frequency content due to poor recording mediums or excessive copying.