| 摘要 |
PURPOSE:To reduce the noise surely inspite of the fluctuation of speed distribution of ventilating air passing through an air-conditioning duct. CONSTITUTION:An air-conditioning duct 12 guides ventilation air from the fan 11a of an air-conditioning machine 11. A plurality of microphones 13, arranged in the air-conditioning duct 12 near the air-conditioning machine 11, detect the noise from the air-conditioning machine 11. An evaluating microphone 14, arranged at the downstream side of the air-conditioning duct 12, detects the noise of an objective point for control. A controller 16 obtains coherence powers between the evaluating microphone 14 and respective microphones 13 and corrects an operating coefficient based on a transfer function between the microphone 13, having the maximum coherence power, and the evaluating microphone 14, then, a signal is processed based on the corrected coefficient and is outputted from a speaker 15. |
