Correlation between the number of present people and the sound pressure level in the student restaurant SvF STU. The simulated dashed green curve in Figure 10 represents the sound pressure level assuming diffuse field conditions (Eq. (2)), assuming 1 person per 4 people present, is talking with average sound pressure level L_S,A,1 m = 54 dB at one meter distance (equivalent with a point source with an A-weighted sound power level of 65 dB [23]). The diffuse field assumption is feasible since for all measured spaces the spectral values of T₃₀ and T₂₀ are very similar and do not deviate too much from EDT.