Teleconferencing Goes Stereo

Over the years, the telecommunications industry has explored many technological frontiers, but the introduction of stereo sound hasn’t been one of them – until now.

Bell Labs researchers recently made a breakthrough in audio technology that makes it possible for the first time to deliver full-duplex stereo sound over an audio or video teleconference. The technology works in an Internet Protocol (IP) environment and can integrate into almost any IP-based teleconferencing system.

Stereo teleconferencing gives participants a better way to hear and comprehend multiple streams of conversation, says Gary Elko, research supervisor in the Murray Hill, N.J.-based speech research department of Lucent Technologies Inc., Bell Labs’s parent company. “It supplies the ‘cocktail party effect’ – the ability to listen in on a particular conversation when there are a bunch of conversations going on around you.”

He adds that stereo technology is well suited for use in an IP environment. “With IP’s audio delay people tend to talk all at once. Stereo will help users sort out the different voices.”

To make the technology work, Bell Labs researchers had to tackle a complex problem called “stereo acoustic echo cancellation.” Without echo cancellation, conference participants would suffer the screeching feedback that occurs when a microphone picks up sound from a nearby audio speaker, forming an acoustic loop.

Current echo-killing schemes rely on a one-channel-cancellation technique, which identifies a single acoustic path between the speaker and the microphone. This approach doesn’t work in a stereo environment because the sound travels along multiple acoustic paths between the speaker and the microphone. To overcome this obstacle, the researchers developed new algorithms that modify the stereo signals in a way that allows for correct audio-path identification without harming the stereo sound.

Stereo conferencing technology has significant potential, says Francie Mendelsohn, president of Summit Research Associates, a Rockville, Md.-based kiosk and telecommunications research company. “It could be kind of cool,” she says. “It’s not something people have been asking for, but if it lives up to Lucent’s promises, it could turn out to be very popular.”

Bell Labs will add the stereo teleconferencing technology to a number of Lucent teleconferencing products, including Lucent Collaborative Video, an IP-based system for PC users. Lucent also plans to license the technology to other companies.