With multiple sound sources and recording devices in a video call / video conference / video collaboration session, one of the big issues that can detract from the “like you are there” experience is the presence of audio echo echo echo echo echo.
But what can you do ? First you have to know who is CAUSING the echo. It is actually sort of easy. If you hear yourself echo, you are not the problem. The one person on the call who says “What echo are you all talking about?” is the source.
Now you can get to work fixing it with the top five ways to quash echo on your next video call:
1) Acoustic Echo Cancellation (AEC) Software – The Windows operating system has echo cancellation technology built in and most video calling software either uses what Windows provides or builds on it. Our experience is that Win 7 and Vista do a better job that XP, so if you are relying on the Operating System to do your AEC, you’ll have better luck with the newer platforms.
However, AEC only has a chance to work when the mic input and speaker output go through a central point (e.g. a sound card, a black box). For example, I do most of my video calls on a laptop with integrated Mic and Speakers. The IDT Sound system processes both input and output and delivers excellent, echo-free performance. However, if your mic input is a USB webcam, and your speaker output comes from the integrated sound card, it is virtually impossible for AEC software to tell what is echo and what is “good” input. Also, some rooms just have too many inputs, outputs and bouncing sound waves for the software to “read” and adjust properly, so you need another solution.
2) Echo Cancelling Microphone (ECM) — An ECM is actually a microphone and speaker built into one unit. We use the Meeteasy of ECMs in our office. They are compact, sturdy, use 1 USB connection and have software or firmware built-in that provides beautiful, echo free sound. In fact, we turn off AEC software when we use an ECM, so that the sound doesn’t go through two rounds of echo cancellation and introduce an unnatural latency into the conversation. The only problem is that ECMs can get sort of expensive, if you have a lot of endpoints. Moreover, if you video conference from a cubicle, having a speaker “sharing” all your video conversations may not be the ideal solution. So, for the cost of a couple lattes…
3) Headset / Ear Buds — You can buy a headset that takes your speaker output and feeds it directly to…your ears. No sound coming out of speakers, means no feedback into microphone and no echo on your call. If you have a set of ear buds from a music player or cell phone, you can accomplish this task and use the money you saved to buy those lattes.
4) Adjust input/output levels or location — I was on a call today with a guy who was generating echo. We took his mic level down a few notches and the echo went away. Similarly taking the speaker volume down can mean the speakers aren’t loud enough to feed back into the mic and thus no echo. In both cases, you have to balance the person’s ability to comunicate on the call with the echo they are introducing. Another similar strategy, if you have a mic that can be moved relative to where the speakers are, is changing the physical distance between speakers and mic. Moving a boom mic away from the speakers, turning external speakers outward, or pulling speakers in front of a mic can mean getting the mic out of pickup range and eliminating echo.
5) Half Duplex — If you don’t want to buy anything and you don’t want to wear anything, and you can’t make AEC software work or adjust levels/locations to get rid of echo, half duplex sound is a final remedy. With half duplex, only one person’s audio is transmitted at a time, so the echo feedback loop never starts.
The downside to half duplex is that the video call doesn’t feel as natural or as interactive as an in-person conversation; and if you are listening to someone who doesn’t ever stop talking, you have no way to interrupt except waving your hands !
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