Acoustical and dimensional properties of the rooms under study, denoted R1, R2 and R3. All rooms are located in the same buildings and are “office” type rooms. R1 and R2 have ceiling acoustic treatment, whereas R3 has not. This explains the particularly high value of RT₂₀ for R3. (a) Reverberation times by octave bands of the three rooms, calculated on omnidirectional component of measured SRIRs, using ITAToolbox [41]. (b) Dimensions and spatial configurations of the sources and listening positions in the three rooms. H value indicates room height. D2 and D4 represents the two loudspeakers, respectively placed at 2 and 4 m from the listener. In each room, the two source positions remain fixed and identical across all participants. Critical distances of the three rooms at 1 kHz were respectively 0.64 m, 0.43 m and 0.37 m. The calculation of critical distances is based on an omnidirectional source.