Research and development engineer, Wil Oxford, used Metric Halo's SpectraFoo to test and measure the high-definition audio for LifeSize Communications revolutionary VoIP conference phone.

AUSTIN, TEXAS: Cold War era nuclear submarines may seem an unlikely source of inspiration for a conference telephone design. But with the assistance of some declassified documents, plus Metric Halo's SpectraFoo analysis software, LifeSize Communications has set a new benchmark in sound quality with a revolutionary phone that combines a patent-pending microphone array with beam forming technology to bring high-definition audio to the boardroom.

According to Wil Oxford, when LifeSize co-founders Craig Malloy and Michael Kenoyer invited him to join the research and development team he knew little about telephony. "I came from a higher-end audio background, so I used SpectraFoo to just go in and measure everything that was out on the market. That way, I knew what the state-of-the-art was and what particular aspects of phones that I liked and disliked."

He continues, "As I got further and further into my own design, which is very different from the way that everything else works, I used SpectraFoo every day to measure the performance of the system, such as THD, frequency response, signal-to-noise ratio, dynamic range - all those things that professional audio people care about."

Oxford says of the new conference phone, "From a quality perspective we're head and shoulders above everybody else and we're continuing to improve, and Foo makes a big difference to that. People say SpectraFoo is a professional tool. Well, we're doing professional audio on this phone. I've used all the traditional tools of the trade that are out there, but I just keep coming back to Foo because it's just so easy for me to use. And it's so easy for me to get to what I need and analyze the data."

Designed primarily for VoIP [voice over internet protocol] operation, the LifeSize Phone(tm) incorporates a circular array of 16 microphones around the periphery of an 11-inch diameter disk and offers a 16kHz frequency response with negligible distortion over an IP connection. "All of the mics are omnis and they're all on all the time. We take the signal from those and we create virtual beams with digital signal processing that can sweep around the room. We can track eight different targets in a room at the same time. It's the same technology that's used in towed passive sonar arrays for a nuclear submarine," explains Oxford.

A typical Los Angeles class sub has an onboard mainframe to process the data from the hydrophone arrays in real-time for threat detection and navigation. "Under the hood we use over a gigaflop of processing to do the things that we need to do," says Oxford of the LifeSize Phone. A gigaflop is one billion floating-point operations per second.

Oxford says that he had a breakthrough about a month into the design process while digging through the University of Texas engineering library stacks. "I realized there were some interesting techniques being used in the radar signal processing world that were equally applicable. That allowed us to drop our processing requirements by a factor of ten. At that point I knew we were onto something. That was the genesis of our circular array. From there we got a product out the door pretty quickly."

In fact, the conference phone was not initially developed as a standalone, according to Oxford, who was initially hired to develop a high-definition audio device to work with the company's high-definition videoconferencing system. That system, LifeSize Room(tm), offers four-way conferencing with 720P definition over a one-megabit link.

"The challenge was to do something equally interesting in the audio space," he says. "I realized that it was a good mic pod to add onto a hi-def videoconferencing system, but it would also be a very good standalone speaker phone. The market for conference phones is easily ten times that of the market for a high-end videoconference system."

Oxford, who is also a recording engineer, has even put the "CD-quality" phone to perhaps the ultimate test. "We put one of our phones about 25 feet away from an orchestra and a choir and recorded a CD of the John Rutter 'Requiem.' We put the phone down in the middle of the hall and formed beams on all the interesting things, such as the soprano solo, the harp and the organ. We recorded them as separate tracks, then a friend of mine mixed them down."

He concludes, "Telephony has changed quite a bit since Bell said, 'Come here, Watson.' Most VoIP systems are capable of at least 8kHz bandwidth, which is quite a bit different from the standard 4kHz telephone bandwidth, and ours is 16kHz. We found that, as we go up in frequency response, what you get is not necessarily just a sense of better quality - although you get that - but it's much more intelligible. The differences between the fricatives and the plosives, and the ability to communicate more effectively, scales very well with the bandwidth."

"I have been a big fan of Metric Halo and of SpectraFoo in particular for well over a decade. At Apple Computer, I used Foo to help me improve the audio quality on the Slot-Loading iMac design as well as the microphones used by Apple's award-winning speech recognition software. I had access to the world's most sophisticated audio tools at Apple and I kept coming back to Foo.

Now at LifeSize, I find Foo an indispensable tool in helping me to quantitatively measure everything from loudspeaker frequency response and distortion to the vibration sensitivity for different microphone configurations."