Assessment of annoyance and cognitive fatigue of open-plan office occupants subjected to noise from two different activities

An open-plan office can be organised into zones, in which different activities can take place (focused individual work, collaborative work, phone communication...) The ISO 22955 (2021) standard recommends acoustic attenuation values between zones that varies according to the activity of the emitting zone (which influences the noise emitted by the occupants of this zone) and that of the receiving one (in which the necessary concentration may vary). The objective of this study was to evaluate the relevance of these target attenuation values. 32 participants who had to carry out a focused individual activity (writing a press review) were submitted to two types of noise environment (representing the noise emitted from a breakout area or that coming from a an area where people mainly have telephone conversations), at four signal-to-noise ratios (in relation to the own noise of the reception area). The exposure time was approximately 35 min, and participants completed questionnaires on their perception of the noise environment, cognitive fatigue (MFI) and mental workload (ICA). The presentation will show the results of this experiment and the practical consequences for the target values of the ISO 22955 standard, in the case of these two disturbing noises.