AFC controls the acoustic environment via multiple microphones and loudspeakers strategically located throughout the space. This type of system generally employs one of the two following methods.
- “Regenerative approach” uses acoustic feedback, reproducing the sound picked up by the microphones via the loudspeakers and then picking up that sound affected by the room’s acoustics once more, thereby creating an acoustic “loop” that amplifies the room’s acoustic energy.
- “In-line approach” uses convolution signal processing to add a variety of synthesized reflected sound data (measured impulse responses) to the sound picked up via the microphones, to create the desired sonic environment.
AFC is a hybrid system that employs both of these methods. Through detailed control of reverberation and early reflections that have a profound influence on auditory impression, the sound propagating throughout the room can be adjusted as required while retaining the natural acoustic properties of the room’s structure.
|Pat.No.||Title||Date of Pat.||Contents|
|5,025,472||Reverberation imparting device||1991||Basic idea Feedback/FIR|
|5,131,051||Method and apparatus for controlling the sound field in auditoriums||1992||Energy exchange|
|5,642,425||Sound field control device||1997||EMR|
|6,072,879||Sound field control unit and sound field controll device||2000||YUME-HIBIKI including EMR & Fluc-FIR|
|6,157,724||Apparatus having loudspeakers concurrently producing music sound and ref||2000||Music instrument including EMR & Fluc-FIR|
|7,474,753||Sound field control apparatus, signal processing apparatus, sound field control program, and signal processing program||2009||Hardware Configuration|