Time evolution of the noise level in STU-Bratislava student restaurant on Monday (a), Thursday (b) and Midday (c). The sound pressure level values are depicted in grey and the number of people present in pink. The acoustic capacity N_max = 40, is indicated by the horizontal black dashed line In d), the difference L_A,eq – L_P,tot is plotted depending on the number of theoretically active sound sources, i.e. half of the persons present.