| 摘要 |
PROBLEM TO BE SOLVED: To provide a unidirectional condenser microphone unit wherein howling is scarce. SOLUTION: In the unidirectional condenser microphone unit, wherein a diaphragm 20 stretched to a support ring 21 and a fixed pole 30 supported by an insulation seat 50 are arranged via a spacer ring 40 opposite to each other and a rear air chamber 31, is provided between the fixed pole 30 and the insulation seat 50, the stiffness s1 of the rear air chamber 31, expressed by (ρ×c<SP>2</SP>×S<SP>2</SP>)/V, whereρis the density of air, c is the sound velocity, S is the effective vibrating area of a diaphragm 20, and V is the volume of the rear air chamber 31, is increased on the basis of the value of the volume V so as to shift the resonance frequency of the omnidirectional component included in the unidirectivity up to a frequency around a high-frequency reproduction limit. COPYRIGHT: (C)2005,JPO&NCIPI
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