The effect of sound masking on employees' acoustic comfort and performance in open-plan offices in Canada

Sound masking systems are commonly employed in open-plan offices to achieve a controlled minimum level of background sound, in order to decrease the signal-to-noise ratio of unwanted incoming speech, thus making it less intelligible and distracting. Many previous studies have investigated the optimal level and spectrum of the masking sound in open-plan offices to balance speech privacy with acoustic comfort of the occupants, but most studies have conducted subjective testing in a laboratory setting instead of actual office environments. Recently, it has been hypothesized that self-generated sound levels from occupants alone in open-plan offices are sufficient to provide a minimum background sound level to achieve speech privacy (ISO 22955). This study, undertaken pre-COVID-19 and with high office-occupancy, aims to examine the relationship between the occupant-perceived speech privacy and different masking sound conditions (no masking, 42 dBA, and 47 dBA masking sound levels) in two operational open-plan offices located in Quebec, Canada. The employees were asked to fill out subjective questionnaires before and after each change in conditions, focusing on how the sound environment impacted their comfort and work performance during the study. Statistical results show that both sound masking sound conditions are significantly more satisfactory for occupants than without the masking sound. This has implications regarding whether office acoustic design guidance can rely on occupant-generated background sound levels to achieve acceptable acoustic conditions. © INTER-NOISE 2021 .All right reserved.