A case study on workstation-dependent acoustic characterization of open-plan offices

Open-plan space is used in interior building design to create shared functional environments. The basic idea is to foster flexibility, cooperation and spaciousness in indoor environments by eliminating any boundaries hindering sight and speech intelligibility, such as walls. However, the complexity of sound propagation in open-plan spaces makes acoustic modelling a particularly challenging problem. Moreover, in open-plan offices (see Figure 1) the acoustic environment is a mixture of machine- and human-made sounds. Thus employees often feel annoyed by various types of acoustic noise. Examples for typical noise sources are speech, walking sounds, environmental noise and working sounds (eg. typing on keyboards). In contrast to the intention of increased cooperation, for tasks requiring high levels of concentration the acoustic situation of the open-plan space is a drawback. Consequently, a number of studies have begun to examine employees' responses to acoustic noise. At the same time, it is unclear which acoustical treatment is better for open-plan spaces in order to improve the well-being in the working environment. The common practices include applying sound absorbing (meta-) materials on ceilings and baffles or screens, or applying sound masking. It is greatly acknowledged that sound and vibration noise is addressed as an important factor in job satisfaction ratings, which is closely related with perceived health conditions. Therefore, it is important to reduce noise annoyances which may impair cognitive performance. However, the acoustics in open-plan offices remain often an unquantified issue. Even in cases where the acoustics are taken into account it is difficult to relate objective acoustic measurements to the employees' subjective feeling. As a result, in many cases measures to improve the acoustics are not targeted on a precise issue.