Exciter (effect)

An exciter (also called a harmonic exciter or aural exciter) is an audio signal processing technique used to enhance a signal by dynamic equalization, phase manipulation, harmonic synthesis of (usually) high frequency signals, and through the addition of subtle harmonic distortion. Dynamic equalization involves variation of the equalizer characteristics in the time domain as a function of the input. Due to the varying nature, noise is reduced compared to static equalizers. Harmonic synthesis involves the creation of higher order harmonics from the fundamental frequency signals present in the recording. As noise is usually more prevalent at higher frequencies, the harmonics are derived from a purer frequency band resulting in clearer highs. Exciters are also used to synthesize harmonics of low frequency signals to simulate deep bass in smaller speakers.

Originally made in valve (tube) based equipment, they are now implemented as part of a digital signal processor, often trying to emulate analogue exciters. Exciters are mostly found as plug-ins for sound editing software and in sound enhancement processors.