Acoustic Echo Cancellation
Echo Cancellation is the process of removing echo from transmitted audio signals. This process is carried out with the help of echo suppressors and echo cancellers. Sometimes they are used simultaneously. There are two types of echo: acoustic and electric (hybrid).
Acoustic Echo
The acoustic echo appears due to regenerative coupling. That happens when the sound from the handsfree speaker enters the microphone in the same room. There are two types of regenerative coupling:
- Mechanical connection between a microphone and a speaker.
- Reflection from the elements surrounding a device.
The following suppression algorithm is applied to eliminate acoustic echo:
- A signal is sent from a distant room.
- The nearest speaker reproduces this signal.
- The signal is received by a microphone at the nearest room.
- At the same time, the signal received from a distant room is being filtered and delayed in order to look like the same signal, that got into a microphone at the nearest room.
- The signal from the near side is subtracted from the filtered distant signal.
- As a result, the given audio signal does not contain echoes anymore and can be transmitted further.
Electric (Hybrid) Echo
This type of echo appears when an electric signal from the data transmission line interferes with the data reception line. This kind of echo exists in analog communication lines and absent in digital lines.
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FAQ
Do I need specialized hardware to eliminate acoustic echo in a large conference room?
While physical acoustic panels and specialized DSP microphones help, modern software algorithms are highly effective at filtering out room reflections. TrueConf utilizes advanced built-in acoustic echo cancellation (AEC) and noise suppression algorithms to automatically clean up audio, even in large, highly reflective conference rooms without requiring expensive external hardware.
What is the difference between acoustic echo cancellation and background noise suppression?
Acoustic echo cancellation specifically targets and removes the sound of the remote participants’ voices bouncing back from your own speakers into your microphone. In contrast, background noise suppression filters out environmental sounds like keyboard typing, paper shuffling, or air conditioners. TrueConf combines both technologies to ensure your voice is transmitted crystal clear, free from both room echoes and ambient noise.
Does the echo cancellation process introduce noticeable audio delay or latency during a call?
The mathematical process of filtering, delaying, and subtracting the reference signal is designed to happen in real-time with minimal processing overhead. TrueConf’s optimized audio processing engine handles acoustic echo cancellation instantly, ensuring that the conversation remains perfectly synchronized and natural without any perceptible lag for the participants.
Will echo cancellation still work if I connect a third-party USB microphone or external speakers?
Yes, software-based echo cancellation analyzes the audio output and input streams regardless of the specific hardware being used. Whether you are using a built-in laptop microphone, a dedicated USB headset, or external room speakers, TrueConf’s adaptive AEC algorithm automatically adjusts to the acoustic environment to eliminate any regenerative coupling or echo.
Since electric echo only happens in analog lines, do I need to worry about it when using a modern IP-based video conferencing system?
You do not need to worry about electric (hybrid) echo if you are using a fully digital, IP-based communication system, as it only occurs in legacy analog telephone lines. TrueConf operates entirely over digital networks and utilizes digital signal processing to completely bypass analog line interference, focusing its advanced algorithms purely on eliminating acoustic echo for pristine digital audio.
What should I do if I still hear an echo during a TrueConf video conference?
If you experience echo, it is usually because the remote participant’s speakers are too loud and their microphone is picking up the sound before the software can filter it. Ask the remote party to lower their speaker volume, use headphones, or ensure their TrueConf client has the correct audio devices selected so the built-in acoustic echo cancellation can function optimally.
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