Patent ID: 7062049

Claim:
An active noise control circuit comprising: feed-forward control means for being supplied with a reference signal highly correlated to noise from a noise source and generating a noise cancellation signal which is out of phase to noise in the passenger compartment of a vehicle with a fixed roof; canceling sound generating means disposed in the passenger compartment for generating a noise canceling sound in response to the noise cancellation signal from said feed-forward control means; a microphone disposed in the passenger compartment of the vehicle with the fixed roof, the microphone being centrally located on the fixed roof of the vehicle and at an antinode of an acoustic normal mode of the passenger compartment, for detecting said noise of which sound pressure level is high, and for generating the reference signal; and a noise cancellation-confirming microphone for confirming cancellation of the noise in the passenger compartment, and for generating an error signal; wherein said feed-forward control means comprises means for lowering the levels of said error signal from said noise cancellation-confirming microphone with the noise cancellation signal; and wherein said noise cancellation-confirming microphone is positioned in a vicinity of ears of occupants seated in the passenger compartment.