First implemented by Yamaha in 1985, Active Field Control (AFC) is an acoustic conditioning system designed to adjust and enhance the architectural acoustic characteristics of facilities such as performance arts venues, houses of worship, theatres and concert halls—while maintaining the natural sonic characteristics of the space. This is achieved by generating feedback loops of microphones and speakers located in the reverberant field of the room to ‘recycle’ the reverberant energy, effectively extending the reverb time.