Decentralized Sound Masking

High speech intelligibility is a common issue in open space offices: phone calls or conversation of colleagues impair one’s concentration. Broadband noise can help reduce speech intelligibility; this is called Sound Masking. However, most people do not tolerate the exposure to noise if it is applied throughout the entire space. Decentralized Sound Masking is a new approach where the broadband noise is used only in proximity to the user.

The concept of decentralized Sound Masking is tested in a field study with scientific evaluation. We use a product from Fa. Nimbus which integrates the Sound Masking into a luminaire. A basic noise is produced by loud speakers directed towards the ceiling. Their volume depends on the sound level in the room. Another speaker is directed towards the user, who can adjust the intensity of the downwards sound signal.

The field study takes place in a modern office building built in 2015. Before and after the test period, we ask the participants of the study about their satisfaction with room acoustics and other potential influences. The duration of usage and the intensity of the speakers are recorded via a data logger. Reverberation time and speech transmission index are measured in all office areas subject to the field study. Extensive surveys and measured room parameters provide valuable information about the desired intensity of the decentralized Sound Masking, as well as about possible improvements of the sound signal used.