In my gig at ZipDX I work with some very interesting people. Barry Slaughter-Olsen is one of those people. Barry is a professor at the Middlebury Institute of International Studies at Monterey, where he teaches the art of simultaneous interpretation to a new generation of language professionals. He’s also the co-founder of Interpret America, a group dedicated to raising the profile of interpreting. Further, he’s the GM of Multilingual Operations for ZipDX.
All of the above builds upon the fact that he’s a tremendously skilled conference interpreter. He also happens to be a self-professed geek, which is handy in business that, like so many others, is facing an onslaught of new technologies.
The other day Barry posed a question via twitter. In reference to Dolby Voice he asked “is this any better than #HDVoice?” It’s good question, so I did a little digging.
In truth, Dolby Voice has been on my radar for several years. It first launched in partnership with BT, who offer BT MeetMe with Dolby Voice to Enterprise clients. More recently WestUC, parent company of PGi, have launched their own Dolby Voice enabled conference service.
What Does Dolby Voice Entail?
It’s not all that easy to get to the facts of the matter. There are a number of videos online, but these are mostly slickly produced clips that sell the service to businesses. There’s not a lot of technical specifics to be found. Nor any straightforward examples of what the service actually delivers.
These facts hampered my initial desired to get analytical with a recorded example. Nonetheless, here’s what I’ve discovered. There are several aspects to Dolby Voice:
- Super-wideband Audio
- Noise Reduction
- Positional Audio
- A Soft Client (Windows, OSX, Android, iOS)
- Legacy PSTN integration
- The Dolby Conference Phone
Super-wideband audio is a telecom term. It means that the system delivers a usable audio channel from 50Hz to between 12 and 16 KHz.
Super-wideband is a long-established capability, common in video conferencing. It’s delivered via various audio codecs including; CELT, Opus, Polycom‘s Siren 14, SILK or SPEEX.
Super-wideband may be considered an improvement over mere wideband (aka HDVoice) which delivers 5- Hz – 7 KHz. However, the additional high frequency extension is an incremental improvement over HDVoice as embodied in G.722. It’s not nearly as dramatic as the initial leap from narrowband to wideband.
Long before the surround sound realm that anchors the Dolby legacy, the company made it’s name by creating noise reduction systems for analog tape recorders. Dolby A and later SR-types were used in professional studios, while Dolby B and C-types were found in consumer cassette decks.
While there were others in that space, Dolby was absolutely dominant. Clearly they know a thing or two about audio processing. That includes noise reduction and level control, which is critically important when mixing multiple sources.
Dolby Voice is a stereo conference service, with the ability to position participants in the stereo image. Remote participants are arrayed in a stereo image, to the benefit of those who are listening in stereo. When a participant is listening using headphones this avoids the sense that all of the voices are coming from the same place in the center of your head. It offers a more immersive audio experience, if you’re wearing headphones.
Note that stereo audio has long been used in video conferencing, although it’s not typically implemented in a fashion that allows the system to shift the location of participants in the stereo image.
A Soft Client
Things like positional audio and super-wideband require a new kind of client. The ubiquity of smart phones and laptops provide the platforms for soft client apps that deliver these new features.
Here again, Dolby isn’t necessarily the first to do this. There have been a number of start-up that featured audio conferencing with positional audio. Some might have leveraged code from Fraunhofer or Freeswitch, which both have such capabilities.
You might recall some time ago when Voxeet appeared on VUC471. Positional audio, mobile devices and soft clients for Windows & OSX…this was their game also.
Legacy PSTN Integration
This is the Achilles heel of all these new systems. Whether it’s voice via Slack, Skype, Wire or whomever…the many advantages are lost when there’s a requirement to allow access from a traditional telephone. In the best case the person connected by the PSTN becomes a second-class participant. In the worst case, they simply can’t join the call.
Happily, Dolby Voice does support legacy telephony. The person connected by telephone has a typical experience. Their presence on the conference is at PSTN call quality, markedly less than those joined via IP-based methods.
The Dolby Conference Phone
This was one of the most interesting things about Dolby Voice. The company understood that they must address the common corporate use case…the meeting room. That’s beyond an app on a smart phone or a laptop. It requires a dedicated solution, which they offer in the form of their own conference phone appliance.
Dolby’s web site has some rudimentary tech specs for this device. They show that it has a basic IP phone mode where it behaves like a nominal SIP conference phone, delivering HDVoice via G.722. It’s compatible with Avaya Aura, Cisco CM and Unify OpenScape Voice.
In a response to a comment I once Ieft on the Dolby blog Dr. Mike Hollier did say that when operating in Dolby Voice mode it uses a proprietary, low-bit-rate codec. That makes a certain amount of sense since it must be passing more than just the audio stream to facilitate positional audio.
Sadly, there’s not much more that I can say about this device. I’ve literally never seen one in person, and all of the material I’ve found online were flashy promotional things that are not an accurate reflection of what it actually delivers.
Answering Barry’s Question
All of the above was an exploration in the hope of answering Barry’s question, simply restated, “Is Dolby Voice better than HDVoice.”
The only answer that I can offer is…maybe…occasionally…for some people. To deliver the claimed benefits the stars must come into alignment. It requires a Dolby Voice-enabled service, a special conference phone, and as much as possible, everyone else using soft client with headphones. That’s a tall order.
Even if these obstacles prove insurmountable, and no-one ever achieves Dolby Voice nirvana, those that connect over IP may still experience high-quality HDVoice. That’s not bad. Not bad at all. That’s what we do every day at ZipDX.