Open-plan offices with room-high sound screens and small amount on collaborative work - Effects of sound masking

Speech privacy is one of the most crucial, yet least satisfying aspects in open-plan offices. The use of sound masking systems, absorbing ceilings, wall absorbers, and high sound screens are commonly suggested to improve the acoustical design of open-plan o ces. However, the use of sound masking systems is not established in German-speaking countries. This paper summarizes the results of laboratory experiments that analyzed the effects of sound masking on the short-term memory performance and subjective perception of annoyance in sound environments with irrelevant background speech (in the following summarized as masking effect). The results imply that steady-state broadband noise may outperform babble or other speech-like sound masking signals. Adjusting the frequency contour and level to the distracting speech signal and using loudspeakers with su cient sound energy between 100 Hz and 200 Hz can improve the masking effect. If the spatial sound field comprising the sound masking signal is localizable and not homogeneous, and the sound masking signal and distracting speech originate from different directions, the masking effect reduces. Simulations show that sound pressure levels of the sound masking signal as low as 38 dB(A) to 40 dB(A) may be sufficient to achieve above-average speech privacy in an o ce with room-high sound screens.