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Let's talk about Acoustic Echo Cancellation, or AEC, 现在我们来说说回声消除或者叫AEC
and the way that you can incorporate it into your Q-Sys Design. 以及这一技术是如何应用到你的Q-Sys系统的设计中的
Now at its simplest, AEC is a process applied to a telephone call 最简单的解释就是,AEC是一种 用于电话呼叫中的处理方式
that prevents the talkers from hearing the echo of their own voices. 以防止说话者听到 自己说话的回声
In AEC jargon there are two locations: the Near End and the Far End. 在AEC技术的术语中,有两个位置术语: 近端和远端
The Near End is typically a conference room with integrated loudspeakers 最典型的近端就是 一个装有扬声器的会议室
in the ceiling or in the table, and at least one microphone. 会议室至少有一个 吊装或者桌面型的话筒
The Far End is the remote caller who may be in their hotel room, or their car, etc. 远端就是一个远程的呼叫者 可能在酒店房间里或者在呼叫者的汽车上等等
Hello?! Can you hear me? 你好?听得见么?
The problem with this telephone call is that the Far End caller's voice 这个通话出现的问题就是 远端呼叫者的声音
is broadcast from the loudspeakers in the Near End room where it travels directly 将通过近端会议室的扬声器广播出来 广播出来的声音又将直接
into the microphone and is transmitted back to the Far End. 进入到会议室的话筒中, 然后回传到远端。
In addition, this direct path is only one of many ways that the voice could go to re-enter the microphone. 而且,这仅仅是进入 话筒反馈声之一
It could bounce off a wall, 还会有墙面的反射声
it could bounce off a person in your room, 从与会者身上的反射声
it could bounce off a wall, against a water bottle, back against the wall, into the back of your head, 声波可能被墙壁反射到到水瓶, 又反射回墙上,再反射到你头上
Onto the ceiling and down again. 然后反射到天花板,最后又反射下来
These are known as acoustic reflections, or echoes. 这就是我们所说的声学反射,或者叫回声
And since these acoustic paths all have different physical lengths, they result in different time delays 由于这些反射声波有不同的物理长度 因此会导致从扬声器到麦克风
from the loudspeaker to the microphone. 不同的延时
And as the sound travels through the air and bounces off of various surfaces, it becomes distorted 声音在空气中传播, 然后在不同的物体表面进行反射,
as different frequencies are absorbed and attenuated. 由于某些频率被吸收或者减弱就会产生失真。
And all of this is sent back to the Far End. 所有这些最后都会被传送到远端
The average latency of telephone audio is about fifty milliseconds, 电话音频信号的平均延时 是50微秒
which means that as the Far End talker speaks, he'll hear all these reflections 这意味着远端的呼叫者 在100微秒之后
of his own voice returned to him one hundred milliseconds later ... 将会听到被回传的 他自己声音的所有反射声。
... which is guaranteed to make anyone tongue-tied. 这种效果绝对会影响 任何一个通话者的心情
A natural solution to this would be to simply 一个简单的解决办法就是
turn down the volume on the return signal while the Far End is talking. 当远端在说话时 调低近端可能产生回传的声源音量
But the problem with that is, that means everyone in the Near End room has to wait until the Far End talker is done. 这种做法的问题是,近端会议室的所有人 都需要等待远端的呼叫者说话完毕后才能再说话。
Try having a productive business meeting with walkie-talkies, 试想如果你用步话机进行一个会议
and you'll see that this kind of one-at-a-time communication simply isn't an option. 你就会发现这种一次只能有一个声音传输的 沟通方式绝对不是一个好办法
So that's where AEC comes in. AEC eliminates the return echo, 所以AEC技术诞生了,AEC技术消除了通话的回声
while preserving the Near End talkers. 让近端的通话者可以同时说话。
Here's a diagram of this audio signal's round-trip journey. 我这有一个图形可以示意这种音频信号的 整个传输过程。
You'd never know it from the outside, but the Acoustic Echo Canceler puts the audio signal through a lot of 但从表面上你看不到,其实AEC 让音频信号通过很多子系统进行处理
subsystems, including the Adaptive Filter and Adaptive Algorithm, 包括自适应滤波器和算法
Double-Talk Detection, 双工检测
Nonlinear Processing, 非线性处理
Noise Reduction, 噪声消除
and Comfort Noise. 环境舒适噪音
All of these subsystems have been combined into a single Acoustic Echo Canceler component. 所有这些子系统全部集成 在一个AEC组件中
Very little adjustment is necessary to make this work in your conference room. 仅需一点小调整,就可以让这个功能 应用于你的会议系统。
And when you combine the AEC component with the Q-Sys Softphone component, 当你将AEC组件、 Q-Sys系统的软电话组件
and your company's Voice over IP Server, 与你的公司VOIP服务器相连接,
You can turn Q-Sys into a fully functional teleconference solution. 你就能将Q-Sys系统转换成全功能会议电话解决方案。