The input source is set to the microphone (mic).

输入源被设置为麦克风(mic)。

youdao

My test unit also came with an odd little add-on microphone poking out from the bottom, even though it had a built-in mic at the top.

我测试的这台电脑还有一个古怪的外置麦克风，从机器底部伸出来，而其实电脑顶部已经有了一个内置麦克风。

youdao

Mic interface and microphone connections, for chatting or recording.

MIC接口与麦克风连接，用于聊天或者录音。

youdao

There should be a microphone -- wait till the mic comes so everybody can hear you.

WHITEHOUSE: "White House to Main Street" Town Hall: Elyria, OH

To capture the highest quality audio, Tiki uses front-and-back facing microphone capsules that actively locate your orientation to the mic for use with multiple speakers or as you move around the room.

ENGADGET: Blue Microphones Tiki USB mic now available at Best Buy, coming to Apple stores July 15th

During the Japanese-only broadcast, the Nintendo CEO also revealed that a standalone microphone accessory is also on its way (the GamePad already packs a built-in mic), with the new peripheral pitched at karaoke fans in its homeland and its new Karaoke service.

ENGADGET: Nintendo Wii U unboxed alongside more details: Multiple users, 'karaoke' microphones and Wii U Chat (video)