Abstract: Example embodiments describe a method for estimating a number of persons present in a room including i) obtaining measurements of electromagnetic sounding signals transmitted within the room; ii) determining at least one reverberation time from the measurements; iii) determining the number of people in the room based on the at least one reverberation time, on a room parameter indicative for a capacity of the room for absorbing the signals and a person parameter indicative for an average capacity of a person for absorbing the signals.