| 摘要 |
PROBLEM TO BE SOLVED: To provide a muffling device having muffling effect to sound of a high frequency range by means of muffling signal provided with an auditory characteristic of human being. SOLUTION: A noise signal x is halved by a signal splatter 15, and one noise signal is inputted to an adaptive digital filter 16 and another noise signal x is supplied to a least square operation part (LMS) 18 through a transmission filter 17. An error signal e from an adder 20 is supplied to the LMS 18 while being weighted in desired frequency through A-characteristic filter 19 and compensating auditory area of human being. In the LMS 18, a constant for the adaptive digital filter 16 is obtained and successively updated by using the least square average algorithm by a known adaptive control so that the energy of the error signal e becomes a minimum. A muffling signal is obtained by using the digital adaptive filter thus determined as a filter to which noise signal is inputted. |
