The use of water features for improving speech privacy and cognitive performance in open-plan offices

Abstract

Noise in open-plan offices, especially irrelevant speech, has detrimental effects on the psychological and cognitive functioning of people. Noise masking has proven to be effective in reducing these effects. Within that context, this research examines the use of water features in masking irrelevant speech and improving the sound environment in open-plan offices. The research comprised five experiments. Experiment 1 examined the preferred sound pressure level of water sounds when used to mask irrelevant speech. The preferred sound pressure level of water sounds was found to be 45 dBA. In addition, the preferred masking level was independent from the intelligibility level of irrelevant speech as well as the type of the water sounds. Experiment 2 examined audioonly and audio-visual preferences of six water sounds when used to mask irrelevant speech. A 37-jet fountain was preferred in the audio-only condition, whilst a 4-step cascade was preferred in the audio-visual condition. The audio-visual condition increased the likelihood of making positive changes in people’s perception by 1.1 to 2.5 times, in comparison to the audio-only condition. Experiment 3 examined the effect of masking irrelevant speech on cognitive performance and subjective satisfaction. Results showed that cognitive performance of a serial recall task, as well as subjective satisfaction, to be significantly higher when irrelevant speech was masked by a water sound, in comparison to a speech-only condition. The gender of participants was found to have a significant effect on cognitive performance. Female participants’ performance was lower than their male counterparts. Furthermore, female participants benefited more from the masking of irrelevant speech. Experiment 4 examined the longer-term effects of adding a water feature in an open-plan office. Satisfaction with the sound environment significantly increased after installing a water feature in an open-plan office. Experiment 5 measured the reduction in the distraction distance associated with installing a water feature in two open-plan offices. The reduction in the distraction distance was measured to be between 8.64 m and 10.05 m, depending on the space tested. The layout of the workspaces played a key role in dictating the importance of the reduction in the distraction distance. Following recommendations and design criteria given in this study, it is possible to use water features in open-plan offices as a means of masking irrelevant speech and creating a pleasant soundscape and work environment which promote cognitive performance and speech privacy and increase subjective satisfaction.