By Kathi Mestayer
Imagine that this is the view from your office window. Not bad—residential neighborhood, skyscrapers in the distance, and the train nearby means you can get to work without driving.
This view is from the Post Office Distribution Center in Oakland, Calif. It’s only 100 feet from the tracks where Bay Area Rapid Transit (BART) trains line up to cross San Francisco Bay.
The office has windows, too, which is nice. When the trains go by (every three to four minutes), accelerating and decelerating (think screeching brakes), those single-paned windows with metal frames not only let the view in, they let the sound in. And if you open them for a little fresh air, well… you can almost feel your teeth rattling.
Ethan Salter is an acoustician at the San Francisco-based Charles M. Salter Associates and was called to help reduce the noise pollution. “It was definitely difficult to communicate by phone, or even face to face, and the noise interfered with the work people were trying to do,” Salter says.
This presents an entirely different noise problem than an office setting where the printer or a conversation in the next cubicle is the culprit. But the principles acousticians use are the same.
The rule of thumb they use is that a signal-to-noise ratio of at least 10 decibels (dBA) is required in order to be able to hear speech over noise. That means the “signal,” or what you’re trying to hear, has to be 10 dBA louder than the background noise, in order for the speech to be intelligible. (The unit dBA measures how humans perceive sound.)
With frequent BART trains and single-paned glass or open windows, that’s a tall order.
Salter worked with the Post Office staff to evaluate the alternatives in terms of cost, aesthetics, and constructability. “One type of window was too expensive, and the owner and contractor wanted to use another, more common window system that would get them a good price,” he says. “So we retrofitted one room at the facility with a double-paned window that had a layer of plastic in between the two panes of glass.” The improvement was about 10 to 15 dBA compared with the existing windows.
Now when postal employees look out their office windows, they can at least have a conversation while getting the job done. And still enjoy that expansive view.
If you have a hearing loss, learn how you can hear better in the workplace in Hearing Health magazine's “Office Space.”
See what steps one busy Northern California restaurant is taking so its patrons can hear one another while dining.
Hearing Health magazine staff writer Kathi Mestayer serves on advisory boards for the Virginia Department for the Deaf and Hard of Hearing and the Greater Richmond, Va., chapter of the Hearing Loss Association of America.