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, the sensitivity of the microphone head is required to be different in all directions. When the included angle between the sound source and the microphone head is 0 °, the sensitivity of the microphone head is high and 180 ° is low. 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.

3. Use of noise canceling microphone head: when there is a fixed direction between the sound source and the microphone head, the sensitivity of the microphone head is required to be different in all directions. When the included angle between the sound source and the microphone head is 0 ° and 180 °, the sensitivity of the microphone head is high and 90 ° and 270 ° is low. In this case, 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 high sensitivity, the unidirectional microphone has low sensitivity, about 6-8db lower than the omnidirectional microphone, and the noise elimination microphone has low sensitivity, about 10-12db lower than the omnidirectional microphone.