The effect of noise absorption variation in open-plan offices: A field study with a cross-over design

Noise has repeatedly been shown to be one of the most recurrent reasons for complaints in open-plan office environments. The aim of the present study was to investigate if enhanced or worsened sound absorption in open-plan offices is reflected in the employees' ratings of disturbances, cognitive stress, and professional efficacy. Employees working on two different floors of an office building were followed as three manipulations were made in room acoustics on each of the two floors by means of less or more absorbing tiles & wall absorbents. For one of the floors, the manipulations were from better to worse to better acoustical conditions, while for the other the manipulations were worse to better to worse. The acoustical effects of these manipulations were assessed according to the new ISO-standard (ISO-3382-3, 2012) for open-plan rooms acoustics. In addition, the employees responded to questionnaires after each change. Our analyses showed that within each floor enhanced acoustical conditions were associated with lower perceived disturbances and cognitive stress. There were no effects on professional efficiency. The results furthermore suggest that even a small deterioration in acoustical room properties measured according to the new ISO-standard for open-plan office acoustics has a negative impact on self-rated health and disturbances. This study supports previous studies demonstrating the importance of acoustics in work environments and shows that the measures suggested in the new ISO-standard can be used to adequately differentiate between better and worse room acoustics in open plan offices.