| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an adaptive type active muffling device capable of maintaining the noise reduction effect even when the amount of arithmetic processing is small and capable of being reduced in size and cost. SOLUTION: Noise is muffled by generating a secondary sound from the noise detected by a microphone 3, radiating this secondary sound from a secondary sound radiation speaker 5, and making the sound interfere with the noise. Here, frequency response characteristics of a signal processing part 4 are made to be converged to an acoustic transfer characteristics between the noise detecting microphone 3 and an error detecting microphone 6 by arranging, in a subsequent stage of the signal processing part 4, a fixed filter 11 for processing frequency response characteristics from an output of the signal processing part 4 up to the error detecting microphone 6 to be only those of a time delay and arranging a time delay processing part 12 for performing time delay processing equivalent to a time delay component left through the processing by the fixed filter 11 between the noise detecting microphone 3 and an adaptive control part 8. As the result of this, the calculation amount of the signal processing part 4 is reduced, and the cost of the calculating device is reduced.</p> |
