In this video, we’ll continue to explore the virtual view of AVX Architect and talk about AEC, or Acoustic Echo Cancellation. Before we dive into some applications with AEC, we need to cover some basic terms and how the AEC works. 
Acoustic echo occurs in a conferencing system when the far-side speech played in local loudspeakers is picked up by microphones in the near-side room and is transmitted back to the far side. This transmitted signal is a delayed version of the original, which causes the echo.  The received far-side signal does not transfer directly from the speaker to the microphone, but is subject to the artifacts of the room. This may include differing signal paths causing reverb, frequency filtering, and attenuation. These effects are the result of the transfer function of the room. This transfer function is also dynamic as objects in the room move or the microphone moves position. 
To subtract the unwanted signal correctly, the AEC processor needs to simulate the dynamic room transfer function. It can then apply that transfer function to the received signal and correctly subtract the modified original signal. Each Omni 256p processor has 80 channels of AEC processing, while the 512p processor has 160 channels. Each channel of processing offers a 48k algorithm, individual or shared AEC references, echo reduction of 40db or more, Echo suppression of up to 80db, noise reduction up to 25db, adaptive non-linear processing, and extremely fast convergence rates of 100db/s, totaling only 16ms of latency.
Let’s review a few AEC terms and their definitions before diving into an application. AEC is the Acoustic Echo Cancellation that removes the far side signal being picked up by the in-room microphones from the signal being transmitted back to the far side of the connection. Convergence Rate is a measure of how fast the AEC algorithm can recognize and remove echo from the signal path. Echo Return Loss, or ERL, is a measure of the coupling between the AEC reference signal and the AEC input signal. Echo Return Loss Enhancement, or ERLE, shows the loss through the linear AEC algorithm, not including the non-linear processing. NC, or Noise Cancelling can also be referred to as noise reduction, and is the process of removing unwanted background signals. Residual echoes are echoes that still might be present due to real-world acoustic conditions and limitations of the linear processing filter. The non-linear processing stage is a part of the processing that further suppresses residual echoes in difficult acoustic environments, while also enhancing performance during double-talk situations when both near-end and far-end speakers might be talking.