https://doi.org/10.1177/1351010X18776431 Building Acoustics 2018, Vol. 25(2) 111–122 © The Author(s) 2018 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/1351010X18776431 journals.sagepub.com/home/bua Comparison of different in situ measurements techniques of intelligibility in an open-plan office Dario D’Orazio , Elena Rossi and Massimo Garai Abstract Acoustic comfort in open-plan offices is a relatively recent research topic and some practices have not yet been consolidated. The goal in these spaces is to achieve good speech privacy at every workstation, reaching a high value of spatial decay of the sound pressure level. In case of refurbishment, a proper measurement of intelligibility criteria is needed, for example, in order to properly calibrate a numerical model or to plan acoustic treatments. This work compares different measurement techniques to evaluate the spatial distribution of intelligibility criteria. In situ measurements were done in an open-plan office used as a case study. Both omnidirectional and directional sound sources with different sound power levels were used, according, respectively, to ISO 3382-3:2012 and ITU-T P.51:1996. Furthermore, compensation algorithms were used in impulse response measurements in presence of Heating, Ventilation and Air Conditioning noise. The study shows, in a preliminary way, how different techniques and equipment can influence intelligibility criteria used in the open-plan office characterization. Results show that the indirect method of measuring Speech Transmission Index could not be used when the background level is high as the case study while the direct method returns good results. Keywords Open-plan office, speech Intelligibility, background noise, sound source characteristics Introduction Since early studies by Warnock, 1 the parameters of acoustic quality in an open-plan office have been calculated based on spatial variation of intelligibility. Several studies showed that objective measurements are related to working performance. 2–4 Department of Industrial Engineering (DIN), University of Bologna, Bologna, Italy Corresponding author: Dario D’Orazio, Department of Industrial Engineering (DIN), University of Bologna, Viale Risorgimento 2, 40136 Bologna, Italy. Email: dario.dorazio@unibo.it 776431BUA 0 0 10.1177/1351010X18776431Building AcousticsD’Orazio et al. research-article 2018 Original Research