Apparatus for actively reducing noise for interior of enclosed space

An apparatus for actively reducing noise for an interior of enclosed space, comprising:

• a) control sound source means for generating a control sound, to interfere with the noise according to a drive signal input thereto, so as to reduce the noise propagated into the interior of enclosed space at an evaluating area in the interior of enclosed space at which a degree of a residual noise sound is evaluated;
• b) residual noise detecting means for detecting the residual noise sound at a predetermined area of the interior of the enclosed space after the noise interference is carried out by the control sound source means and outputting the detected residual noise sound as a residual noise signal;
• c) reference signal detecting means for detecting a signal related to a noise source and processing the detected signal as a reference signal;
• d) controlling means for outputting the drive signal to said control sound source means on the basis of the output residual noise signal of said residual noise detecting means and the reference signal of said reference signal detecting means so that a performance function is minimized, said performance function being established thereby on the basis of the output residual noise signal of said residual noise detecting means and the drive signal output to said control sound source means and including a term of the drive signal output to said control sound source means multiplied by an effort coefficient;
• and
• e) changing means for directly changing the effort coefficient so that a contributivity of the drive signal means to the performance function is varied, and further including divergence detecting means for predictively monitoring whether a divergence of control sound derived from said control sound source means occurs at the evaluating area and wherein said changing means changes the contributivity of the drive signal to the performance function according to a result of the monitoring by said divergence detecting means.

An apparatus for actively reducing noise sound for a vehicular compartment, comprising:

• a) an electrical-acoustic transducer which generates a control sound, to interfere with the noise sound in response to a drive signal input thereto, to be interfered with the noise sound in response to a drive signal so as to reduce the noise sound at respective evaluating points of location in the vehicular compartment;
• b) an acoustic-electrical transducer which detects a residual noise at predetermined positions of the vehicular compartment after the interference of the control sound with the noise sound by said electrical-acoustic transducer and output a residual noise signal indicating the detected residual noise;
• c) detecting means for detecting a signal related to a noise generating state from a vehicular noise source and outputting a discrete reference signal indicating the signal related to the noise generating state;
• d) controlling means for establishing an performance function on the basis of the residual noise signal and transducer drive signal and for outputting the drive signal to said electrical-acoustic transducer so that the performance function is minimized on the basis of the residual noise signal of said acoustic-electrical transducer, the reference signal of said detecting means, and, furthermore, the electrical-acoustic transducer drive signal;
• e) divergence detecting means for detecting an occurrence of divergence of the control sounds at evaluating points of location and outputting a divergence indicative signal whenever the divergence occurs;
• and
• f) contributivity changing means for changing a contributivity of the electrical-acoustic transducer drive signal to the performance function in response to the divergence indicative signal derived from said divergence detecting means.

An apparatus for actively reducing noise for an interior of enclosed space, comprising:

• a) control sound source means for generating a control sound to interfere with the noise according to a source drive signal input thereto for reducing the noise propagated into the interior of enclosed space at an evaluating area in the interior of enclosed space at which a degree of a residual noise sound is evaluated;
• b) residual noise detecting means for detecting the residual noise sound at a predetermined area of the interior of the enclosed space after noise interference is carried out by the control sound source means, said residual noise detecting means outputting the detected residual noise sound as a residual noise signal;
• c) reference signal detecting means for detecting a signal related to a noise source and processing the detected signal as a reference signal;
• d) controlling means for outputting said source drive signal to said control sound source means, said controlling means operating for minimizing a performance function by generating said source drive signal in response to said residual noise signal outputted by said residual noise detecting means, said reference signal outputted by said reference signal detecting means, and said source drive signal outputted by said controlling means itself, said performance function being established thereby on the basis of said residual noise signal outputted by said residual noise detecting means and said source drive signal outputted to said control sound source means;
• e) changing means for changing a contributivity of said source drive signal to said performance function, and
• f) divergence detecting means for predictively monitoring whether a divergence of control sound, derived from said control sound source means, occurs at the evaluating area from a state in which the performance function becomes minimized,
• g) wherein said changing means is responsive to a monitoring result of said divergence detecting means for changing the contributivity of said drive signal to said performance function.