A system for enhancing the acoustical properties of both indoor and outdoor spaces, particularly for unamplified speech, song, and music. Systems are subdivided into those that primarily change the natural reverberation in the room, increasing its level and decay time (reverberation enhancement systems); and those that essentially replace the natural reverberation (sound field synthesis systems).

Both systems may use amplifiers, electroacoustic elements, and signal processing to add sound field components to change the natural acoustics. Sound field enhancement is used to produce variable acoustics, to produce a particular acoustics which is not attainable by passive means, or because a venue has one or all of the following deficiencies: (1) unsuitable ratio between direct, early reflected, and reverberant sound; (2) unsatisfactory early reflection pattern; and (3) short reverberation times.