Turning Down the Noise

I work at home and I like that, a lot.

But my neighbor has a little barky dog that makes a lot of noise. It reminded me of an article about sound masking, noise cancellation, and acoustical engineering that I recently wrote for Minnesota Technology Magazine (www.minnesotatechnology.org). Noise control is pretty interesting technology. (At Minnesota Technology, I write a column called Ask Mr Technology. The whole magazine is online and makes for very good reading.)

Noise,” said the brooding German philosopher Arthur Schopenhauer,“is the most impertinent of all forms of interruption. It is not only an interruption, but is also a disruption of thought.”

Workers in noisy environments like yours must contend with frequent thought disruptions. But don’t give up hope, as there are techniques for dealing with disruptive noise in the workplace. According to acoustical expert Steve Orfield, president of Minneapolis-based Orfield Laboratories, sound-masking can be an effective way to provide speech privacy and minimize distractions from noisy environments.

Sound masking consists of an electronically generated noise distributed throughout a workspace. This increases the ambient noise, thereby “masking” other sounds and reducing the intelligibility of speech.“ Sound masking makes use of a specially tuned random noise generator. The noise is used as a base which is shaped by an equalizer to make it unobtrusive and most effective to speech intelligibility,” explains Orfield.

But even with sound masking, your cubicle neighbors can still hear you talking with your bookie on company time. “During our research in the 1970s, we found that a normal speaker in an office environment could be heard 20 feet away” says Orfield. “When we put in sound masking, that dropped to 12 feet.“

The original work spaces we designed measured 12 feet,” he adds.“But now work spaces have shrunk as small as 6 by 6 feet.So even with masking, the person next door can hear what’s going on in your cube.”

Is there anything better? A technique called noise cancellation goes beyond mere sound masking. In noise-cancellation systems, undesired sounds are cancelled out by computer-generated soundwaves that are exactly 180 degrees out of phase to the offending sound. But, says Orfield, sound cancellation is only effective in contained areas and on constant noise problems such as hums and vibrations. For example, if you’ve got a noisy air duct running throughout a hotel, you can build speakers into the duct to completely cancel out the annoying duct-related sounds.

Noise cancellation doesn’t work on random or higher-pitched sounds such as traffic noise or human speech. But research into other types of devices is ongoing. Perhaps sometime soon, a noise cancellation technology will arrive that won’t just mask the shouting next door, but eliminate it completely.