Many office buildings use sound-masking, an acoustic technique, to improve the privacy of those speaking while reducing the level of distraction for those who can't help but overhear. A new study from researchers at Rensselaer Polytechnic Institute suggests the era of white noise may be done. Natural sounds — such as recordings of a forest or flowing water — might improve the moods and cognitive abilities of workers, while providing some necessary acoustic privacy in open-plan offices.

Your office chair is ergonomic, the air you breathe is conditioned, but how much attention has been paid to your acoustical comfort? In recent years, architects have begun to address this issue directly when designing open-plan offices. The favored technique is use of a sound masking system, which aims to make distractions less annoying by raising the level of a background soundscape. As you might expect, this renders the talk of co-workers unintelligible beyond a certain distance.

Pumped in through discretely installed speakers, these custom-designed systems have relied on the same masking signal for nearly 40 years: a simple, steady-state electronic signal most of us refer to as white noise.

Mountain Streams

Previous work by Dr. Jonas Braasch, an acoustic architect and assistant professor at RPI, demonstrated people's ability to focus improved when exposed to natural sounds rather than either silence or machine-based sounds such as white noise. Taking this research one step further, Braasch and grad student Alana DeLoach recently designed a new experiment in which 12 participants are exposed to different sound environments while they perform a task requiring close attention. The three acoustic settings are: a typical office soundscape with no masker; a typical office soundscape masked by white noise; and a typical office soundscape masked by natural sounds.

During each visit, the participants encounter only one of the three stimuli while performing an assigned task. Meanwhile, the researchers investigate the moods and productivity levels of each participant. Notably, the researchers designed the natural sound used in the experiment to mimic the sound of a mountain stream.

“The mountain stream sound possessed enough randomness that it did not become a distraction,” DeLoach explained in a press release. “This is a key attribute of a successful masking signal.” The experiment is ongoing, still the researchers presented early findings at a meeting of the Acoustical Society of America.

“‘Natural’ sounds as masking sounds have the ability (with equal success as conventional masking sounds) to meet standards and criteria for speech privacy while enhancing cognitive functioning, optimizing the ability to concentrate, and increasing overall worker satisfaction,” wrote the workers in their presentation abstract. Time to erect a memorial to white noise.

Source: DeLoach AG, Carter JP, Braasch J. Tuning the cognitive environment: Sound masking with ‘natural’ sounds in open-plan offices. Meeting of the Acoustical Society of America. 2015.