Guest Column: An “ear opener” to HD voice in conferencing

By Randolph Resnick, Producer VoIP Users Conference” URL:

We began using the ZipDX ( wideband conference bridge about one year ago. I had been doing PSTN and g711 SIP conferences two years before that.

Over the three years, I have moderated thousands of hours of conferences, and the change to wideband was definitely an “ear opener.”   I noticed certain improvements right away, while others were brought to my attention by David Frankel of over the course of the year.

The most cogent argument for HD is the reduction of fatigue. Guests always ask how long the conference is and we tell them it’s between 15 minutes and one hour or so, depending on what they feel comfortable with. In the end, guests leave after 60-90 minutes because they must get on with their day, not because they are tired of conversing.

On the other hand, the VUC probably sets longevity records. After the guest spot in the first hour, the general chat will continue for 3 to 8 hours. The participants are comfortable with the sound of high quality audio. They feel at home and this is what has established our group as a “club” rather than a podcast.

One of the problems with doing live audio with 30-50 people on the channel is people “stepping on each other” (multiple voices at the same time). This is exacerbated by lag, which might be around 90 to 150 milliseconds or more, causing people to interrupt each other. In wideband, the effect of this is less disturbing because they are able to follow the flow more closely. It is much easier to recognize individual voices, a key factor for interactivity in our discussions.

On a normal PSTN quality call, requests to repeat are frequent. People are only asked to repeat what they say if they have actual packet loss or distortion of some kind on their end. This rarely happens with those called in via G.722 wideband.

Other audio problems such as noise or room reverberation are less disturbing. In fact, the human factor kicks in here as listeners can hear backgrounds more clearly and joke about “missing your train” or recognizing a breed of dog barking, the age of children or the sounds of cooking utensils!

We often have non-native English speakers on. I recall a conference where an Indian sounded nearly incomprehensible, but I spoke to the same person in a wideband context and had no problem. Further, the non-native speaker will be better able to understand if the audio is higher quality wideband.

We have been experimenting with transcriptions and when we do this, transcribers (both human and mechanical) have a much easier time with wideband audio than with normal quality G.711 or G.729 recordings.

Post-conference listening is an important part of what we do at the VUC. There are large numbers of people interested in VoIP in Asia, Australia and New Zealand who can’t participate because of the time difference. We receive positive messages about the improved quality of the recorded versions.

In the same vein, we find comprehension to be better, especially in long technical discussions. Because a two-way conversation is a good measure of live comprehension, my observation is that people are experiencing something closer to in-person interactivity. This is the whole point in doing the VUC live!

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