13 California Buildings News • Q2 2020
Moving from Open Offices Will Improve Acoustics Stressful Noise Is Workers' Biggest Challenge to Performance
By Greg R. Enenstein While people transition back to working in an office, rather than from home, it feels appropriate to reevaluate and find ways to improve the office experience. As acoustical engineers, we are constantly contemplating ways to make offices healthier and more productive, all while maintaining the collaborative benefits of a physical office space. In order to take on this task, we must first accept that open offices face steep acoustical challenges. In fact, in surveys throughout the country, poor acoustics is often cited as the number one problem. The complaint of poor acoustics can be divided into two concerns: open offices are too noisy, and they don’t provide enough speech privacy. Acoustical issues in an office can be particularly detrimental to a work environment. A study at Cornell University showed that exposure to constant low-intensity noise in an open office setting can be result in increased stress levels and decreased motivation (Evans, Johnson, 2001). Another study at the University of Nebraska showed that exposure to irritating or unpleasant background sounds can decrease performance and problem-solving abilities (Errett et al, 2006). So, if we are looking for productive, healthy, and happy workers, accounting for acoustics at open plan offices is truly crucial. Acoustical consultants have been working on ways to quantify, model and recommend improvements to alleviate these issues for decades. An excellent summary of some approaches to reduce distractions, including office zoning strategies, can be found in GSA’s 2011 Sound Matters. At Salter, we have worked on over 500 projects where we have analyzed and made recommendations to improve speech privacy in open plan offices. This process can start with performing measurements in the physical offices to quantify performance with some technical engineering metrics including Noise Criteria (NC), Reverberation Time, and Privacy Index (PI). After using an assortment of computer modeling tools to process the measured data, recommendations are developed. In other cases, we have modeled these metrics during the design phase to help with decisions before the space is built. Overall, in order to make an open office space less noisy and simultaneously increase speech privacy, it will take a combination of improvement strategies to meet a target performance. These core strategies can be summarized as follows: provide appropriate background noise levels, limit the reverberation time, incorporate barriers, and modify the layout.
Provide appropriate background noise levels
Often, open office spaces rely on mechanical systems to provide ambient noise levels. Unfortunately, mechanical systems are not always consistent. When they are off or on low speeds, noise levels will be lower than when operating under a full load. Since speech privacy is a function of background noise levels, it is easier to overhear conversation when an environment is quiet. Therefore, it is important to not only design mechanical systems to appropriate background noise levels, but also maintain these appropriate background noise levels. This can be accomplished by incorporating electronic sound masking. Electronic sound masking usually consists of a system of speakers within a ceiling, or suspended from the ceiling, that subtly boost background noise levels by playing white noise, or another spectrum of sound. Sound masking can reduce distractions, as well as improve speech privacy. (Continued on page 32)
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