Comfort Distance—A Single-Number Quantity Describing Spatial Attenuation in Open-Plan Offices

ISO 3382-3 is globally used to determine the room acoustic conditions of open-plan offices using in situ measurements. The key outcomes of the standard are three single-number quantities: distraction distance, rD, A-weighted sound pressure level of speech, Lp,A,S,4m, and spatial decay rate of speech, D2,S. Quantities Lp,A,S,4m and D2,S describe the attenuation properties of the office due to room and furniture absorption and geometry. Our purpose is to introduce a new single-number quantity, comfort distance rC, which integrates the quantities Lp,A,S,4m and D2,S. It describes the distance from an omnidirectional loudspeaker where the A-weighted sound pressure level of normal speech falls below 45 dB. The study explains why the comfort criterion level is set to 45 dB, explores the comfort distances in 185 offices reported in previous studies. Based on published data, the rC values lie typically within 3 m (strong attenuation) and 30 m (weak attenuation). Based on this data, a classification scheme was proposed. The new quantity could benefit the revised version of ISO 3382-3.