ACTIVE SILENCER AND SILENCING METHOD

摘要

PURPOSE:To obtain a large silencing quantity over a wide frequency band by providing an inverse filter equalizing the transmission characteristic from a speaker to a monitor microphone in a duct between an adaptive FIR filter and the speaker. CONSTITUTION:An inverse filter 6 to equalize a transfer function from a speaker 4 to a monitor microphone 5 in a duct 1 and to superimpose its compensation signal onto an inverse sound signal is provided between the speaker 4 and an adaptive FIR (Finite Impulse Response) filter 4 generating an inverse sound signal with opposite phase and same amplitude with respect to noise. Thus, the input signal (detection signal by the monitor microphone 5) for the coefficient revision of the adaptive FIR filter 3 is not subjected to the transfer function from the speaker 4 to the monitor microphone 5. Then a large silencing quantity over the entire object frequency is obtained.