Acoustics for Media Conferencing
Jun 19, 2014 12:51 PM, By Cynthia Wisehart
“‘Videoconferencing’ is a term that always confuses me because there is always audio. Sometimes there is no video. So it should really be ‘media conferencing’ or ‘audio/video conferencing,’” says studio architect and acoustician John Storyk. He says he gets the calls, often too late, when people realize that the audio part of their videoconference isn’t working, usually due to the acoustical gremlins that thrive in the hard, elegant, glassy habitats of most boardrooms.
“Try to make the environment as non-reveberant as possible.” Storyk says. “Reflections and in particular, disturbing reflections, coming back very close in time, are problematic. They’re often interesting in music, and sometimes helpful in audio control room environments, but they are not an asset in videoconferencing; 99.9 percent of the time they’re just a liability.
“That’s easier said than done because many videoconferences take place in live conferencing environments, not in a dedicated telepresence environment. Conference rooms are often highly architectural, they have a big table—a big liability—hard ceilings, lots of glass. They’re beautiful architecturally, not particularly interesting acoustically. There’s the battle when the room wants to have a lot of architectural features. There are tricks for intelligent control of reverberations and reflections. We now have absorbing plaster. There is absorbent transparent surfacing, which can go in front of glass surfaces. There is microperf wood paneling, allowing wood to become acoustically absorptive! There are a lot of options in the world of materializing. The acoustics community has become very aware of these developments, but the systems integration community is not always as aware of these. Architects are still learning.
“Always try to use intelligence with microphone and speaker placement. That feels like that’s in the category of systems design, but I don’t make that much distinction between systems and acoustics. In a media conferencing room, why put microphones in the ceiling far from the sources? Try to be as close to the sources as possible and have as many localized mics as possible. Dedicated goosenecks are usually going to be best, or retractable mics that are local to each speaker—that and intelligent echo cancelling and usage management—turning mics on and off when people are speaking. This design is not always possible, but this type of design effort is a good starting point.
“Please bring an acoustician on early into the process. We often get called in too late. The traditional story is the architect lays out rooms, tables and chairs, screens, and they move on. Systems team comes in and has equipment on their minds. They see acoustics as maybe a discipline that will take away from the systems budget. The installation is complete and acoustic issues remain! The system works, but it sounds like the Lincoln Tunnel at the receiving end. Although a simplified story, it is not an unfamiliar one.
“We view this type of environment and system as one design process: architecture, systems, acoustics. This is not a terribly complicated idea, or even a very expensive way to work. And from a problem-solving standpoint, it could be just as simple as adjusting the orientation of the room before it’s too late or treating one surface—says the back 8ft. of one wall.
“In the example above, at the Interim Services boardroom in Ft. Lauderdale, there’s glass in the back that overlooks a triple-high atrium. A perforated curtain with a 6in. air space makes it work for media conferencing and for the interior designer. In the ceiling, a combination of low-frequency control and mid-frequency absorption—plus arranging the room geometry wider—all made the room comfortable and intelligible to the ears.”