3. The directional of microphone: the unidirectional and the noise canceling microphone have vents at the bottom; oppositely, the omnidirectional microphone is completely sealed.

• 麦克风指向性:麦克风背有有气孔的；就是有指向性或抗噪型的麦克风；完全密封的；就是全指向的麦克风.；收藏指正