Audio

A Question About Chromebox-For-Meetings and USB Conference Phones

Not long a reader posed this question about USB speakerphone devices;

“Hi Michael – I read your blog article about chromebox for meetings. I’m in the UK and I think there will be good takeup when its launched here but I’m concerned about sound quality mic and speakers in untreated rooms. Have you found any USB table top devices  matrix mics with high quality speaker that could be integrated at proportionate cost? – Thanks, John”

It’s an interesting question. As I was answering him via IM it occurred to me that the answer might be worth sharing.

There are a lot of USB attached speakerphones available. I’ve tried quite a number over the years. Some are good. Some are cheap. As you can imagine, rarely are the good ones cheap. The major difference to be considered is whether the device undre consideration is intended for use by an individual or a small group.

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Questioning New Dimensions In Conference Audio

Headset vs Conference PhoneI’ve long had a fascination with spatial audio processing. This was in part why Voxeet caught my attention when the service initially launched. It was over a year before we were able to have them appear on VUC #471 on January 10th.

From that session you may recall that Voxeet offers a binaural conference service. Participants join a conference using a PC smart phone application. They use a stereo headset allowing the client application to provide placement of the individual participants within a controlled sound stage.

Voxeet is interesting. However, it’s not exactly clear what aspect of the service is most compelling. At point of launch they used the Speex audio codec, which allows wideband audio (aka HDVoice.)

In the recent v2 release their PC client has been moved to a WebRTC foundation, leveraging Opus. I’ve done a quick analysis of their updated online demo. Newly fitted with American voices where there were once French accents, it presents 16 KHz usable audio path, suggesting a 32 KHz sample rate. It certainly sounds very good.

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Binaural Fun With AmbiExplorer For Android

AmbiExplorer_framedMy issue with use of the term 3D with reference to binaural voice conferencing service stems from the fact that I’ve been having some fun with real 3D audio over the past couple of months. This has come about since Hector Centeno released AmbiExplorer for Android, an application that lets us decode Ambisonic recordings for binaural playback in headphones.

AmbiExplorer plays back first-order B format files as well as UHJ encoded stereo files. As opposed to simply left, center, right, etc. a B format file is actually comprised of four channels known as W, X, Y & Z. These correspond to three directional signals and an omnidirectional reference signal.

By performing some matrix math on these signal in a coordinated fashion the entirety of the soundstage can be transformed in 3D space. AmbiExplorer decodes the four signals into a binaural feed, allowing the user to rotate their listening perspective in real-time. You can think of it as a 3-axis “balance” control.

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Podcasting: A Killer Application For Binaural Conferencing

Earlier this week a morning’s news dump brought with it something from Shel Holtz of Holtz Communication + Technology, a communication professional and long-time podcaster. He penned some interesting observations about the use of audio on the web in, “Listen up! You may be producing audio sooner than you think.” His post helped cast a new light on my perspective of binaural conference services like Voxeet and Dolby Voice. While I may have some reservations about their use in business, these could be killer tools for podcasters!

I must admit I was tempted to title this post with reference to binaural conference calls “getting rid of the voices inside my head.” That’s the value of the spatial effect, it expands the soundstage such that the call participants seem to be arrayed around one’s head instead of piled up between the ears.

For a podcast that has two more participants binaural conferencing is definitely an improvement over voices in mono. However, to make this convenient Voxeet et al would need to offer local call recording in their client. At present this is not offered, although it is on the Voxeet wish list.

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This is the sort of “3D” that I will not up with put!

3DRemember the opening sequence Sesame Street? Well, this post is brought to you by the number 3 and the letter D…cuz some of you weren’t paying attention all those years ago!

Both Voxeet and Dolby Voice are interesting binaural conference services. However, some of the marketecture being deployed sets off alarm bells in my mind. Despite claims to the contrary, and the echo of such claims by the media, I don’t believe that what they offer is “3D audio.”

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