| 摘要 |
A boundary microphone is provided to effectively reduce noises caused by external electromagnetic waves by providing electrostatic shielding, including on the portion of lead wires from a microphone unit to a circuit board. The boundary microphone has a base plate, a cover, a circuit board, and a microphone unit mounted in the opening with a metallic holder. A shield pattern for electrostatically shielding inside of the recess with the base plate is formed on the circuit board. The holder is configured to include a cylindrical section into which a rear end side of the microphone unit is fitted, and a D-cut section in which a part of a circumferential surface and a base surface of a cylinder with a base integral with the cylindrical section are cut away in parallel to a board surface of the circuit board, and the lead wire is routed within the D-cut section.
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