ACTIVE NOISE CONTROL

摘要

2084671 9217936 PCTABS00016 A system for reducing noise of a noise generator such as a fan located in a housing includes a short duct (118) directing air to the fan housing. An input transducer (17) is located in the duct (118) at a position further removed from the fan than cancellation device (18) which is also located in the duct (118). An electronic control device (21) with embedded frequencies (22-25) related to the steady state operation of the fan inputs cancellation signals to the cancellation device (18). The input transducer (17) also responds to the random noise of the fan to provide control signals to the control device (21) for generating signals for the cancellation device (18). The input duct (118) can be multi-cellular with respect to the input transducer (17) and the cancellation device (18).