More is less - Positive effects of higher volume ventilation sound on cognitive performance and acoustic comfort in offices

Sound emissions of ventilation units are mostly referred to as noise and are subject to a minimization policy. Silencing causes technical effort and sometimes even higher energy consumption. Additionally, this study reveals that silencing may be counterproductive in open-plan offices, since employees may even benefit from higher volume ventilation sound. This positive effect occurs when disturbing background speech is masked by ventilation sound. In this study acoustics of an open-plan office at one receiver positon incorporating background speech were auralized. Then ventilation sounds of two different decentralised ventilation units at three ventilation rates producing sound emissions in between 25 and 45 dB(A) were added. Participants were exposed to these sound scenarios during a laboratory experiment. Results reveal that participants performed better at a working memory task during presentation of one of the high volume ventilation sounds and acoustic comfort and privacy were judged to be better as well. However, sound quality of ventilation sounds needs to be investigated and purposefully adapted since different effects were found for the two ventilation units, although the overall A-weighted sound pressure levels were comparable.