Abstract
Active noise control using the feed-forward method requires an enough long distance (d) between the reference microphone and the control speaker, to satisfy the causality law. In this research, it was proved that the high sampling frequency and the high computation speed could make the distance d very short. A compact active acoustic cell whose d is 10mm was developed by using a flat speaker and a FPGA controller with 100kHz sampling frequency. Even in the case with an ordinary dynamic speaker whose diaphragm is 70mm diameter, the above high speed signal processing system could reduce the distance d down to 60mm. This is effective for realizing the active acoustic shielding system.
