PURPOSE: To provide the microphone equipment of the primary sound pressure gradient type in which uniform directivity is obtained over a wise frequency band and to provide the microphone equipment in which sharper directivity than that of the primary sound gradation type microphone at a low cost without increasing the scale of a sound collection part.
CONSTITUTION: The microphone equipment is provided with an acoustic tube 21 of a prescribed length and plural sound holes at the side face of the acoustic tube 21 at a proper interval and covered with an acoustic resistance material. A 1st omnidirectional microphone 23 is fitted to one end of the acoustic tube 21 while its diaphragm is directed to the outside of the acoustic tube 21, a 2nd omnidirectional microphone 24 is fitted to the other end of the acoustic tube 21 while its diaphragm is directed to the inside of the acoustic tube 21, and the equipment is provided with a subtractor 25 that subtracts an output of the 2nd omnidirectional microphone 24 from an output of the 1st omnidirectional microphone 23.
KANAMORI TAKEO
FURUKAWA HIROMOTO
IBARAKI SATORU
