Miniaturization of a Narrow-Angle Directional Microphone with Suppressed Rear Sensitivity

Abstract

This paper describes a miniaturization of a narrow-angle directional microphone that enables rear sensitivity to be significantly suppressed. The microphone assembly comprises of a line microphone capsule and a second-order pressure gradient directional microphone. This combination successfully reduced the residual rear sensitivity of conventional line microphones. The previously proposed microphone is too long to set in a small space. Therefore, the microphone is miniaturized by using small electret condenser microphone capsules, which are stacked in the small case, and by modifying the line microphone capsule's directivity to hypercardioid. The proposed microphone successfully suppresses rear sensitivity by more than 20 dB compared to the frontal sensitivity in the frequency range from 130 Hz to 2.5 kHz. Furthermore, it can be driven by a normal 48 V phantom power supply. Finally, the microphone was tested in several on-the-spot broadcasts, and it proved to be effective for practical use.