| 摘要 |
PURPOSE:To supress unnecessary sound and to collect efficiently voices of plural speaking persons by arranging one microphone element at the center and four microphone elements on circumferences of concentric circles, and constituting a sound-collection system by changing the weight at the center and on the circumference. CONSTITUTION:A microphone element 5 is installed at the center and in addition, microphon elements 1-4 are installed on circumferences of concentric circles. Output signals of these microphone elements 1-5 are added by an adder 11 after they are weighted by attenuators or amlifiers 6-10 and addition outputs are taken out. When an attenuation factor (or an amplifying factor) is adjusted so that it will become the weight of -1 by attenuators (or amplifiers) 6, 7, 9 and 10, or 4 by the attenuator (or the amplifier) 8, directional characterstics of this sound collection system show nondirectionality inside the horizontal surface, and show directionality of cos<2>theta (theta: an angle from the horizontal surface) on the vertical surface. According to this, voices of speaking persons can be collected uniformally, and noises from other directions can be suppressed. |
