Chris Kranky

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Wideband call quality

Chris KoehnckeChris Koehncke

Voice quality is a highly subjective matter in the VoIP world; it’s like trying to describe to someone what the color ‘blue’ looks like. Engineers tackle it (as we saw in my previous posting) on a technical front with a rigid formulation charts. Researchers often do subjective testing which results in a MOS (mean opinion score) but the score range is only 0-5 with 5 being excellent. G.711, the equal to what we perceive as traditional telephone quality, ranks a MOS of 4.2. Can it get any better than this?

The industry hasn’t helped matters – who wants to advertise they have “crappy” voice quality? Thus every device has “quality audio”, or “high quality” or “superior”. With the advent of new voice codecs with wideband audio a new series of adjectives have emerged “HD Voice”, hidef, “high definition voice” and so on. Companies such as Skype are now touting their SILK wideband codec, Global IP Sound with their HD Voice GIPS iSAC codec and Polycom with their Siren variant of the grandfather of wideband codecs, G.722.Hdvoice The wireless industry has long understood the relationship
between call quality and call duration. If you’re having a bad connection during a call, you communicate as simply and quickly as possible and hang up, ready for the experience to be over. Hence the mobile companies carefully track areas where call durations are short as it likely indicates they have a poor signal condition.

In our era of reducing travel costs (both time spent and actual cost of transit), significant  improvements to voice result in a “being there” quality that’s hard to quantify, but you know it when you see it.

For example, I utilize Skype in my office with quality speakers and the microphone from my webcam (which I rarely use – what’s the point of seeing me). When people call me, it’s almost like their  sitting in the room next to me, we’re not having a telephone call, we’re having a conversation. It’s a combination of decent speakers/microphone and the crystal clear wideband audio codec utilized by Skype. I’ve had similar experiences using newer Polycom IP handsets. The audio quality is a noticeable different.

The result is that I’m willing to be on this ‘phone’ calls longer and I don’t have to devote as much energy to trying to understand so much “how” something is being said and can focus instead on “what” they are saying. I’ve found myself happy to engage with nearby colleagues (that I just
as easily could see in person) via this method, saving me time and increasing my overall efficiency.

Increased call quality is a benefit to all of us and while we haven’t yet been able to put a quantifiable dollar benefit to it, anyone whose experienced it has had the ‘moment’ when it’s clear to them as to the derived benefit.