Acoustic echo and Reverb

Acoustic echo refers to the sound that the speaker plays out and sends back to the far end when the microphone is picked up, allowing the remote interlocutor to hear his or her voice. Acoustic echoes are also divided into direct echoes and indirect echoes. Direct echo refers to the speaker playing out the sound without any reflection directly into the microphone. The echo delay is shortest, and it is related to the voice energy of the remote speaker, the distance between the speaker and the microphone, the angle, the playback volume of the speaker and the sensitivity of the microphone pickup, and so on. Indirect echo is the Echo collection that comes into the microphone when the sound of the speaker is played through a different path or multiple reflections.

When the echo returns more than ten MS, the ear can hear a noticeable echo, which interferes with the normal call. For IP network environments with relatively large latency, the latency is easily reached in MS, so the echo must be cleared.

When the sound waves in the indoor transmission, to be walls, ceilings, floors and other obstacles to reflect, each reflection should be absorbed by obstacles. In this way, when the sound source stops sounding, the sound waves in the interior to undergo multiple reflection and absorption, and finally disappeared, we feel that the sound source stopped sound after a number of sound mixing continued for a period of time. This phenomenon is called reverberation , which is called reverberation time .