Omni-directional Microphone Working Principle

Omni-directional microphone working principle

Omni-directional microphones, so-called omni-directional, are relative to interface microphones and traditional microphones. Interface Mai and traditional microphones are simply used to collect sounds. They are only responsible for collecting sounds. Omni-directional microphones are based on sound pickup. They have more playback functions and can play the other party’s sounds. Of course, with this feature, there are a series of problems. The biggest problem is the problem of echo. We know that omni-directional mic is integrated with the microphone and microphone, and the microphone's effective pickup range Usually can reach 3-6 meters, then the sound source of the loudspeaker to play the sound is certainly within this range, if there is no treatment, no accident, the sound played by the microphone will be picked up by the microphone, and then pass To the other side, this time forms the "echo" heard by the other party;

Acoustic echo means that the sound played by the speaker is picked up by the microphone and sent back to the far end, so that the far-end talker can hear their own voice.

Acoustic echo is divided into direct echo and indirect echo. Direct echo means that the sound played by the speaker directly enters the microphone without any reflection. This kind of echo delay is the shortest, it is related to the speech energy of the far-end speaker, the distance between the speaker and the microphone, the angle, the playing volume of the speaker and the pick-up sensitivity of the microphone. Indirect echo means that the sound played by the speaker is different. The set of echoes generated by the microphone after one or more reflections of the path.

When the echo return time exceeds 10 ms, the human ear can hear a clear echo and interfere with normal conversation. For an IP network environment with a relatively large delay, the delay can easily reach 50 ms, so echo must be cleared.

Echo cancellation mainly uses the echo cancellation method, that is, the size of the echo signal is estimated by an adaptive method, and then this estimate is subtracted from the received signal to cancel the echo. Echo cancellation is usually done at the gateway.

Through its second-generation echo cancellation algorithm (256 ms for echo cancellation), Midea achieved a major domestic technological breakthrough in the direction of echo cancellation. Therefore, the Tenveo omni-directional microphone has a built-in echo cancellation chip to ensure that there is no echo in your use.

The use of omni-directional wheat is roughly a conference room with an effective area of 60 square meters or less, and only one conference room can be used. This is due to the distance of pickup - there is an upper limit for the distance to pickup, so it should be around 60 Within; far from the pickup distance, with two or more devices will interfere with each other.