Since the 1980s, some opera companies have been experimenting with acoustic enhancement, a subtle type of sound reinforcement system. Acoustic enhancement systems help to give a more even sound in the concert hall and prevent "dead spots" in the audience seating area. Acoustic enhancement systems use "...an array of microphones connected to a computer" which processes the sound and directs it to an array of amplifiers and loudspeakers spread out in the concert hall. The computer processor is designed to augment the natural acoustics in the hall and prevent "dead spots." However, as concertgoers have become aware of the use of these systems, debates have arisen, because "...purists maintain that the natural acoustic sound of voices [or instruments in a given hall should not be altered."