| 摘要 |
PURPOSE:To make the main maximum direction of a synthesizing sound pressure coincident with the shaft direction of a speaker to a wide frequency band by providing a straight line phase FIR type digital filter in a first signal path. CONSTITUTION:At the first signal path provided by branching a common signal path, a low pass filter 7 is provided and at a second signal path, a delaying circuit 2 having a delaying time, in which the delaying time of the signal path corresponds to the delaying time of the first signal path, is provided. The low path filter 7 is composed of an A/D converter 8, a straight line phase FIR type digital filter 9, a coefficient generating circuit 10 and a D/A converter 11. From the output signal of the delay circuit 2, the output signal of the low pass filter 7 is subtracted with a subtracting circuit 4. The outputs of the subtracting circuit 4 and the low path filter 7 are respectively supplied to speakers 5 and 6. |
