Technology has progressed in all areas. UC and Videoconferencing are no exception. Gone are the days when we had just a few kilobits of bandwidth and we were trying to squeeze audio and video through a couple of 64 kbps ISDN channels. And that was using not-so-efficient compression algorithms (from our perspective today). Should we still have audio quality issues in video calls ?

Now, we have Megabits of bandwidth… if your video is not at least 720p HD you start complaining and the audio has got better and lower in bandwidth consumption because of the very efficient algorithms used. (14 to 22 KHz of frequency response).

This should be music in our ears!

And yet, no, it is not always like that.

Technology can be used in the right and wrong ways. Efficient and inefficient ways. Productive and unproductive ways. And most of all, technology is there for the users to understand it as much as possible. If the users see technology in a different way than the technology creators, then this may be an issue.

Audio systems for Video Codecs

For example: You have this great new Videoconferencing system, that you just installed in your conference room. It should sound like CD quality audio at least. And yet, it does not….I remember discussions with some customers. I was responsible for designing their videoconferencing solution for their conference rooms. When it came down to the actual items of the estimate, it was a disappointingly repetitive pattern that went like this:

  • what is this item for ?
    • This is the main VC system
  • What is this item for ?
    • This is the camera shelf
  • What is this item for ?
    • This is the software option for multipoint
  • What is this item for ?
    • This is the audio system with a powerful subwoofer and two satellite speakers
  • OK, this one, we do not need. We’ll use the TV speakers. Thank you.

So much technology, so much effort from international bodies to create better audio compression, so much money spent on the codec, and the benefit disappears due to poor audio. Videoconferencing saves you thousands in flight costs and that more than justifies the cost of a proper audio system.

Audio System

The first reason for the audio quality issues in video calls is that TV speakers of flat TVs are of the worst kind, because a) they are flat, b) they are there for basic audio (=awful audio) because flat TVs are supposed to have a surround sound system or a sound bar, c)  Flat TV speakers will barely cover your living room, let alone a medium to large conference room, d) because of (c) you will turn it up so much that you will hear distortion and funny noises from the TV chassis !

Room Acoustics

Another reason for poor audio is the architectural choices of the room. When non-reflective surfaces are recommended, a common answer is “the architect does not allow such interventions”. Users many times interpret poor audio as a video codec fault when in reality it is the acoustics of the meeting room.

Microphone density and placement

Microphone density, type and placement is very important and can help avoid or create more audio quality issues in video calls. Rooms with poor acoustics and a lot of echo are begging for more dense microphone distributions. The more the mics, the less the echo picked up because wherever you are, there is always a mic close to you and your voice picked up directly from the mic is very loud compared to the reflected audio waves. Few microphones (or even just one) will not be enough to cope with this type of acoustic phenomena. (There is another component needed here, the audio processor / echo canceler which is discussed in another post).

Even if the room has good acoustics, you still need to cover the space depending on the size of the room and the pickup range of the microphones. Many times, a second microphone that is recommended for a long table with more than 10 participants is regarded by customers as an effort to upsell. In reality it is just serving the exact need of the room. To the far end, the people at the front seats sound loud, and the rest very faint…sometimes people will even start dragging the mic around by the wire… 🙂

So if we can trust technology and follow the rules and technical norms, there is always a way to make video calls sound great and avoid these audio quality issues in video calls.

 

Dionissis Zervas, UC Engineer

CVE, PCVE, CCNA, MCSE

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