ADAPTIVE ACTIVE NOISE CANCELLATION APPARATUS

• Main Authors: TAMURA, HIROSHI, SARUTA, SUSUMU, SUZUKI, SEIICHIROU
• Format: Patent
• Language: English
• Published: 26.08.1992
• Edition: 5
• Subjects: ACOUSTICS; ACOUSTICS NOT OTHERWISE PROVIDED FOR; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING,NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; MUSICAL INSTRUMENTS; PHYSICS; SOUND-PRODUCING DEVICES

An adaptive type active noise cancellation apparatus comprises a first sensor (14) for detecting a noise generated by a noise source and outputting a detection signal, a filter (16) having a predetermined filter coefficient and filtering the output signal from the first sensor by using the predetermined filter coefficient and outputting a filtered signal, a speaker (17) for receiving the filtered signal and generating a sound corresponding to the filtered signal, an active noise cancellation control system (12) for actively canceling a noise at a control target point by using the sound generated by the speaker, a second sensor (20), arranged at the control target point, for detecting a sound at the control target point and outputting a detection signal, and an adaptive control system (11) for receiving the output signals from the first and second sensors and adaptively updating the filter coefficient in accordance with a change in state of a system to which the active noise cancellation control system (12) is applied. The adaptive control system (11) includes a switch (15) for stopping the active noise cancellation control system (12) in adaptive processing, and a correction system (18, 19, 21, 22) for correcting the output signal from the first sensor (14) or the second sensor (20) by using a transfer function corresponding to a delay in a spatial system between the speaker (17) and the second sensor (20) and a delay required for calculation processing.