Directional Sound Field and Spatial Speech Decay: Impact of Sound Absorption and Screen Height in Performance Spaces and Open-Plan Offices

Abstract

This study investigates the spatial decay rate of speech in performance spaces and open-plan offices, focusing on the effects of sound absorption and screen height. Utilising parameters such as D2, SD_2, SD2, S (decay rate) and Lp, A, S, 4mL_p, A, S, 4mLp, A, S, 4m (sound pressure level at 4 meters), the research evaluates how acoustic environments impact speech transmission. Through detailed experiments on different screen heights (1.2 m, 2.1 m, and 2.9 m) and material absorption, it was found that increasing screen height significantly reduces the spatial speech decay in open-plan offices, but only up to a certain threshold. The results suggest that while acoustic enhancements like screens and absorptive materials improve speech privacy, over-reliance on single- number ratings can lead to misclassification of office acoustics. This research provides insights for optimising room acoustics, ensuring speech privacy, and meeting acoustic comfort standards.