Communication system for reproducing an interactivity of physical type between at least two players, especially two participants in a meeting, comprising: at least one display screen (20, 21, 22) having dimensions comparable to those of a white board and comprising a first device designed to detect at least one human finger position by measuring a first physical quantity which varies as a function of a human finger contact on said screen (20, 21, 22), characterized in that it comprises: - a plurality of objects (30, 31, 32) emitting a uniform signal at different frequencies distinguishing the objects from one another, said signal being a continuous train of ultrasounds at predetermined frequency, - a second device designed to detect at least one position of an object (30, 31, 32) distinctively from that of a human finger, by measuring a second physical quantity linked with a reception of said uniform signal which varies as a function of the position of the object (30, 31, 32) with respect to the screen (20, 21, 22), and - a computer (10, 11, 12) configured at least to receive the position of the human finger, detected by the first device, and the position of one object from the plurality of objects, detected by the second device; and in that said computer is programmed at least to: - allocate a zone of the screen (20, 21, 22) to writing; - modify in said zone allocated to writing a local visual aspect which follows the position of the object (30, 31, 32) on the screen when said object emits said uniform signal, to generate a function of writing in a given colour or of deletion which depends on the frequency of the signal of the object whose position is detected; - vary said zone allocated to writing as a function of a displacement linked with the position of the human finger on the screen (20, 21, 22). at least one display screen (20, 21, 22) having dimensions comparable to those of a white board and comprising a first device designed to detect at least one human finger position by measuring a first physical quantity which varies as a function of a human finger contact on said screen (20, 21, 22), characterized in that it comprises: - a plurality of objects (30, 31, 32) emitting a uniform signal at different frequencies distinguishing the objects from one another, said signal being a continuous train of ultrasounds at predetermined frequency, - a second device designed to detect at least one position of an object (30, 31, 32) distinctively from that of a human finger, by measuring a second physical quantity linked with a reception of said uniform signal which varies as a function of the position of the object (30, 31, 32) with respect to the screen (20, 21, 22), and - a computer (10, 11, 12) configured at least to receive the position of the human finger, detected by the first device, and the position of one object from the plurality of objects, detected by the second device; - a plurality of objects (30, 31, 32) emitting a uniform signal at different frequencies distinguishing the objects from one another, said signal being a continuous train of ultrasounds at predetermined frequency, - a second device designed to detect at least one position of an object (30, 31, 32) distinctively from that of a human finger, by measuring a second physical quantity linked with a reception of said uniform signal which varies as a function of the position of the object (30, 31, 32) with respect to the screen (20, 21, 22), and - a computer (10, 11, 12) configured at least to receive the position of the human finger, detected by the first device, and the position of one object from the plurality of objects, detected by the second device; and in that said computer is programmed at least to: - allocate a zone of the screen (20, 21, 22) to writing; - modify in said zone allocated to writing a local visual aspect which follows the position of the object (30, 31, 32) on the screen when said object emits said uniform signal, to generate a function of writing in a given colour or of deletion which depends on the frequency of the signal of the object whose position is detected; - vary said zone allocated to writing as a function of a displacement linked with the position of the human finger on the screen (20, 21, 22). - allocate a zone of the screen (20, 21, 22) to writing; - modify in said zone allocated to writing a local visual aspect which follows the position of the object (30, 31, 32) on the screen when said object emits said uniform signal, to generate a function of writing in a given colour or of deletion which depends on the frequency of the signal of the object whose position is detected; - vary said zone allocated to writing as a function of a displacement linked with the position of the human finger on the screen (20, 21, 22).