Just how many decibels are conducive to healthy workplace?
The answer is 50 according to a new study recently published in the journal Nature Digital Medicine by Sudha Ram, professor of management information systems at the Eller College of Management at the University of Arizona.
The study – part of a larger workplace well-being research - – suggests that if employers intend to build or redesign their office spaces with employee health and well-being in mind, they might want to consult acoustical engineers who can help them dial in conditions for good environmental sound, said Sternberg, who is also director of research for the UArizona Andrew Weil Center for Integrative Medicine and a member of the university's BIO5 Institute.
"Everybody knows that loud noise is stressful, and, in fact, extremely loud noise is harmful to your ear," said study co-author Ester Sternberg, director of the UArizona Institute on Place, Wellbeing & Performance, in an article on the university's website. "But what was new about this is that with even low levels of sound – less than 50 decibels – the stress response is higher."
The study's co-author, Karthik Srinivasan, an assistant professor at the University of Kansas, points out that, "when we think about well-being, typically we think about emotional or mental well-being. We hardly ever consider the physiological well-being or the actual 'what's happening in our body,' which is also important to understand when we're continuously exposed to environmental factors such as sound."
The new study, which was part of Sternberg's larger research project – called Wellbuilt for Wellbeing – in partnership with the U.S. General Services Administration, determined the results after measuring the impact of sound on office workers who worked in four different buildings. Participants wore two devices for three days. One device, worn around the neck, measured sound levels in the person's work environment. Another, worn on the chest, measured participants' physiological stress and relaxation levels, using heart rate variability, or the varying lengths of time between each heartbeat.
Heart rate variability is a direct result of breathing so as a person inhales, his or her heart rate slightly increases, and it decreases as the person exhales, causing variability between heartbeats. The researchers measured heart rate variability alongside environmental sound, then used mathematical modeling to determine how changing sound levels affect a person's physiological well-being.
The results showed that when a worker's environmental sound level was above 50 decibels, each 10-decibel increase was related to a 1.9% decrease in physiological well-being. But when office sound was lower than 50 decibels, each 10-decibel increase related to a 5.4% increase in physiological well-being.