| 摘要 |
PURPOSE:To improve the precision of sound detection by a microphone and to improve the reliability in a system, in an active muffler device using an adaptive FIR filter. CONSTITUTION:In the active muffler device detecting a noise in a duct by a detection microphone 3 and radiating an inversion sound with a phase opposite to and an amplitude equal to the noise from a speaker 4 into the duct, plural detection microphones 3 are arranged on positions equally distant from a noise source in the duct, and an acoustic mixer 6 adding the output signals of respective detection microphones 3 is provided. Then, by the addition with the acoustic mixer 6, the noise components of the output signals of respective detection microphones 3 are canceled, and the precision of detecting the noise is improved. Further, even when one piece of detection microphone is failured, the precision of detecting the noise is maintained by other detection microphones 3. |
