| 摘要 |
PURPOSE:To obtain excellent acoustic characteristics by controlling plural state- variable type BPFs controlled by a microcomputer, calculating its mean value by using a measured transmission characteristic, comparing it with transmission characteristic data, and setting characteristics of the state-variable type BPF. CONSTITUTION:Analog switches 20, 27 are closed to the side of a pink noise generator 28 and a microphone amplifier 26 by executing a measuring program, and a noise is sounded from a reproducing loudspeaker 24 installed in a car chamber 23 through an amplifier 22. Subsequently, overall transmission characteristics of the loudspeaker 24 and the car inside are inputted by a microphone, and inputted to a filter circuit part consisting of state-variable type BPFs 33, 34, an amplifier 30, switches 37, 38, etc., through the amplifier 26. These filters 33, 34 are controlled by a microcomputer 41, its mean value is brought to program operation by using measured transmission characteristic data, and a center frequency of the filters 33, 34, and a corrected peak dip level Q are set from an operation result obtained by comparing said value with the transmission characteristic data. |
