The present invention includes an electronic controller (17), and an acoustic sensor (13, 14), according to the configuration of the acoustic noise reducing device and an acoustic output device (16). The controller is connected to a sensor (13, 14) and the output device (16). Output device, for fluctuations in the gas flow, by the acoustic source (15), respectively, and the acoustic wave (p +), the oscillation, including the acoustic source (15) reflected acoustic wave propagating toward the (p-) generation It is disposed within the enclosure to be. Acoustic sensor (13, 14) is disposed between the acoustic source (15) and the output device (16), acoustic waves (p-+) and a signal (s1, s2) from the acoustic wave field including (p-) Measure. Electronic controller (17) receives sensor signals from these sensors (13, 14) (s1, s2), a correction signal (18) is calculated and generated based on characteristics of the estimated acoustic waves (w + and w-) configured to output the correction signal (18) devices (16), so as to transmit to actively minimize the acoustic waves (p-).