PURPOSE: To improve activity by using one microphone as an ultradirectional microphone and a one-point stereophonic microphone.

CONSTITUTION: Microphone units M21 and M22 are arranged at a prescribed interval (d) so that their axes are rotatable counterclockwise at least to 60 or 120°. The outputs of the units M21 and M22 are connected to changeover switches S1 and S2, which have contacts a1 or a2 connected to input terminals of a mixing circuit ADD through a phase shift processing circuit PS or directly; and the output terminal of the ADD is branched into two to be connected to changeover switches S3 and S4. Those changeover switches S1∼S4 are associated with one another. In this constitution, the switches S1∼S4 are only connected to contacts a1∼a4 to obtain an ultradirectional output. To obtain a one-point stereophonic output, the switches S1∼S4 are only connected to contacts b1∼ b4.