This issue has been covered to some degree in previous questions, however, a discussion on this topic may provide help in answering any future questions. Please chime in for anything that I miss.
User reports hearing an echo on a call, what do you do? First thing to note is that echo is normally caused by the side who does not hear it. If there is two participants on a call and user A is hearing an echo, the issue is caused on user B’s side. If there are 3 or more participants, the echo will normally be heard by all participants except the side causing it. What is happening is that the cause of the echo is due to a failure of echo cancellation (also known as AEC) of the video conferencing system that participant is using. There are rare exceptions to this rule. One notable exception would be with Icon endpoints and presentation sound, which the Icon will play through its local speakers. Generally, you can rely on this rule of thumb, “If you hear an echo, the issue is not on your end. It is the other side of the call that has the echo issue”
Lifesize endpoints as well as Lifesize computer clients have echo cancellation built in. AEC works by detecting a voice signal going in one direction on a circuit, and then keeping that signal from going back in other direction
Common scenarios and solutions:
Echo caused by a Lifesize endpoint using HDMI monitor for sound out.
If using HDMI monitor for sound out, make sure the Monitor is configured properly for video conferencing. If the monitor has a “Game” mode, please enable this on the monitor. If no “Game” mode, please disable all special features. These features may be: digital surround sound, simulated surround sound, Motion Smoothing, Cinema or film mode, digital noise reduction, Motion enhancement, Any other processing or enhancement tool on the monitor. Please note, some monitors may not have the processing power to decode audio in real time
What is happening is that when using HDMI to send the audio to play over the speakers of a Television will introduce latency to the sound. There will be a delay between when the Lifesize system outputs an audio signal and when that signal is emitted from the speakers in the room. All echo cancelers have a "tail" which is the amount of time after the audio signal is output to the speakers that they look for the corresponding echo coming in the microphones in that room. These special features may add to that delay or may introduce variation to that delay which may make it harder or impossible for the echo cancellation to spot and remove that audio signal. This can also be send with an external audio system with processing. This is the reason it is recommended that the TV settings be put in "game mode" and/or all processing/effects turned off in the TV setup menus. Game mode seeks to minimize the latency through the TV's processor and get the audio/video to the speakers/screen as quickly as possible.
Audio processing on the television by audio features (such as digital noise reduction, bass boost, digital surround sound, and simulated surround sound) can also introduce distortion to the audio signal. This may cause issues with the AEC as well as delay the processing of the audio. As the echo canceler looks for the signal that was sent out coming back in through the microphones significant distortion or alterations to the audio signal make it difficult for the echo cancellation to recognize the signal and remove it. Other sources of distortion can also be a problem, such as poor quality speakers found in many consumer televisions or speaker volume set too high. Quick summary of steps
Changes made on the monitor:
Game Mode – If available.
No game mode, look for the following types of items.
Digital surround sound
Simulated surround sound
Motion Smoothing – may be called "TruMotion," "CineMotion," or "Smooth Motion Plus"
Cinema or Film mode
Digital noise reduction
Any other processing or enhancement tool on the monitor.
Set monitor volume to half way and adjust Lifesize volume as needed.
Place sound input device at least 5 feet from the monitor’s speakers
Use the Lifesize Phone or Speakers connected to the Line Out port.
Note, some monitors do not have the processing power to decode audio in real time or may have a poor design speaker arrangement and may always give an echo. In this case, you will need to seek an alternative such as line out speakers or Lifesize Phone.
Echo caused by Lifesize endpoint using an integrated sound system.
Using a sound mixer. Generally, this will be used if there are multiple speakers and microphones. You would normally want to have the sound mixer/audio DSP to manage echo cancellation and disable the echo cancellation (AEC) on the Lifesize endpoint. The built in Acustic Echo Cancellation on Lifesize Endpoints is set up to manage a simple sound in and sound out configuration, such as one sound input device and one sound output device. The use of multiple microphones and speakers placed in complex arrangement would not be properly managed by this build in echo cancellation. In these complex arrangements, the external audio mixer will need to process the echo cancellation. Since only one AEC should be used at a time, the AEC should be disabled on the Lifesize endpoint. If using an Icon, it should be set for Integrated Audio Mode. Note this is only supported on the Icon 800 and Icon 600. More information on settings below. For 220 systems, Active Microphone and Audio output should be set for a “no-AEC” setting.
Icon 800 – This is set in the Web User Interface
Icon 600 – This can be set using SSH See Icon API documentation for more detail
Command to enable/disable
audio setintegratedaudio on
audio setintegratedaudio off
See Icon API documentation for more detail
If sound mixer is being used for audio input, and a Lifesize Phone Gen2 or HD is being used, the user may need to disable the Microphones on the Phone.
Command to enable/disable:
audio setforcelineinmic on
audio setforcelineinmic off
See Icon API documentation for more detail
Intermittent echo with an Icon
If after following the above steps with an Icon and issue remains, it is possible that the Icon adaptive delay setting for echo cancellation may need to be disabled in some configurations. You can disable the “Adaptive Delay” settings using the Icon API
Command to enable/disable:
Audio setAdaptiveDelay on
Audio setAdaptiveDelay off
Some other points:
Speaker/ microphone layout may have an effect. Location of the microphone in relation to the speakers. Make sure that the Lifeisze MicPod or Lifesize Phone is at least five feet away from the speakers
In room acoustics can also have an effect, such as hard walls, glass walls, hard ceilings, large broad conference tables, and so on may also cause audio distortion due to these services reflecting sound.
I may have missed something. If so, please add a comment below.