The requirements for the use of different pointing types of microphones are as follows:
1. Use of omnidirectional microphone: when there is no fixed direction between the sound source and the microphone and the microphone is required to have the same sensitivity in all directions, just open a hole on the front shell of the microphone. For example, telephone handle, mobile phone, hands-free headset, etc.
2. Use of unidirectional microphone head: when there is a fixed direction between the sound source and the microphone head, and the sensitivity accepted by the microphone head in each direction is required to be different, the sensitivity of the microphone head is the highest when the included angle between the sound source and the microphone head is 0 ° and the lowest when 180 °. At this time, it is necessary to open a hole on the shell before and after the sound hole of the microphone head. Such as car phone, etc.

3. Use of noise canceling microphone head: when there is a fixed direction between the sound source and the microphone head, and the sensitivity accepted by the microphone head in each direction is required to be different, the sensitivity of the microphone head is the highest when the included angle between the sound source and the microphone head is 0 ° and 180 °, and the lowest when 90 ° and 270 °. At this time, one hole must be opened on the shell before and after the sound hole of the microphone head. Such as car phone, etc.
4. Under the same other conditions, the omnidirectional microphone has the highest sensitivity, the unidirectional microphone has a lower sensitivity, about 6-8db lower than the omnidirectional microphone, and the noise elimination microphone has the lowest sensitivity, about 10-12db lower than the omnidirectional microphone.