This column is intended as an interactive forum to discuss audiovisual and acoustical technologies, and your questions make the job of writing absolutely enjoyable. Several readers have told me that one of the most frustrating experiences is to have a meeting interrupted by sounds from the adjacent spaces separated by "airwalls." While painstaking for the planner, there are ways to respond to this ongoing challenge. Let's look at the issues and some solutions.
Developers' Directive The mantra of facility developers and managers is flexibility. They want to accommodate all requests for all sizes of meetings, and turn no one away. So when meeting facilities are built, the directive to the architect is to provide operable partitions (commonly referred to as "airwalls," a trademark of one manu- facturer's early product that used air-inflated bladders to seal the partitions to the structure). These movable partitions cost many tens of thousands and even hundreds of thousands of dollars to install, and range in quality from poor to very good. How well will they work for your meeting? It depends.
A number of factors determine how effectively the panels will isolate one space from another. Some of these factors are invisible to the eye, but the seals at the top and bottom of the panels can be inspected, and I encourage you to do so. Here's how.
Look for Yourself First, have the facility's house crew set the partition in place. Once set, walk the length of the partition examining the bottom where the seals should be tight to the floor. If any have not dropped or been cranked down, ask the crew to correct them. If there are doors at the "pocket" where the partitions are stored, make sure the doors are closed against the partition.
There shouldn't be extension cords or other cables running under the partition. Push firmly on each of the panels. If they sway, the bottom seal is not tight enough. If there are any pass doors, latch them firmly. These doors are a major cause of sound leaks. If you're not using them and if they are not a fire exit, have the doors sealed with tape.
Next, go into the adjacent space and turn up the house lights. Go back into your meeting room and ask for the lights to be turned off. Let your eyes adjust to the dark for a few minutes then (carefully) move around the middle of the room and look at the seams between the partition panels and at the top and bottom. If you see a light leak, that means there is a sound leak, too. If the leak is at the bottom, ask the facility to re-seat the drop seals. If the leak is at the top, there's usually very little that can be done unless the top seals are replaced. If the leak is at the edge, have the facility try to re-set the panels.
To put things in perspective, the better partitions are rated to provide 53 to 55 points of sound isolation between adjacent spaces. In reality, properly installed and set, these partitions typically only provide 45 points at best. However, just one square inch of gap will lower that rating to 32 (maximum) points of isolation. And, it doesn't matter if that is one hole right in the middle or many tiny holes. Further, that small leak can cut the effectiveness of your partitions by more than half (10 points reflects an apparent halving or doubling of sound volume).
Of course, visiting your meeting room when an actual event is taking place on the other side of the partition is the most reliable experience. But however you test the sound barrier, make sure you're satisfied with the outcome. If you are not, move your meeting, have the facility arrange service upgrades for the partitions and re-test, or, if possible leave the adjacent room unoccupied during your meeting.