Apparatus for natural ventilation of a room, said apparatus comprising: - a room delimited by walls, - at least one door or one window installed in one of the room walls and comprising a fixed stationary frame surrounding an opening frame supporting a glass panel, - a ventilation passage provided on the door or the window and which communicates between the outside of the room and the inside of the room in such a way as to allow natural ventilation between the outside and inside of said room, - a noise absorber capable of attenuating sound waves propagating in the ventilation passage, the attenuation being realized by the generation of a counter-noise which is superimposed on said sound waves, wherein, - the opening frame is mounted movably in the stationary frame between: ∘ a closed position wherein the opening frame is hermetically integral with the stationary frame in such a way as to prevent any ventilation between the inside and outside of the room by the door or the window, ∘ and an open position wherein the open frame is detached and separated from the opening frame in such a way as to allow natural ventilation between the inside and outside of the room by the door or the window, - the ventilation passage is delimited by at least one fixed wall and at least one movable wall, said fixed wall being integral with the stationary frame or with the wall and said movable wall being integral with the open frame, - the fixed wall and the movable wall are configured in such a way that: ∘ when the opening frame is in the closed position, the movable wall and the fixed wall are in an arrangement that hermetically seals the ventilation passage and that prevents any ventilation between the inside and outside of the room by said ventilation passage, ∘ when the opening frame is in the intermediate open position, the movable wall and the fixed wall are in an arrangement that frees the ventilation passage and that allows natural ventilation between the inside and outside of the room only by said ventilation passage. - a room delimited by walls, - at least one door or one window installed in one of the room walls and comprising a fixed stationary frame surrounding an opening frame supporting a glass panel, - a ventilation passage provided on the door or the window and which communicates between the outside of the room and the inside of the room in such a way as to allow natural ventilation between the outside and inside of said room, - a noise absorber capable of attenuating sound waves propagating in the ventilation passage, the attenuation being realized by the generation of a counter-noise which is superimposed on said sound waves, wherein, - the opening frame is mounted movably in the stationary frame between: ∘ a closed position wherein the opening frame is hermetically integral with the stationary frame in such a way as to prevent any ventilation between the inside and outside of the room by the door or the window, ∘ and an open position wherein the open frame is detached and separated from the opening frame in such a way as to allow natural ventilation between the inside and outside of the room by the door or the window, ∘ a closed position wherein the opening frame is hermetically integral with the stationary frame in such a way as to prevent any ventilation between the inside and outside of the room by the door or the window, ∘ and an open position wherein the open frame is detached and separated from the opening frame in such a way as to allow natural ventilation between the inside and outside of the room by the door or the window, - the ventilation passage is delimited by at least one fixed wall and at least one movable wall, said fixed wall being integral with the stationary frame or with the wall and said movable wall being integral with the open frame, - the fixed wall and the movable wall are configured in such a way that: ∘ when the opening frame is in the closed position, the movable wall and the fixed wall are in an arrangement that hermetically seals the ventilation passage and that prevents any ventilation between the inside and outside of the room by said ventilation passage, ∘ when the opening frame is in the intermediate open position, the movable wall and the fixed wall are in an arrangement that frees the ventilation passage and that allows natural ventilation between the inside and outside of the room only by said ventilation passage. ∘ when the opening frame is in the closed position, the movable wall and the fixed wall are in an arrangement that hermetically seals the ventilation passage and that prevents any ventilation between the inside and outside of the room by said ventilation passage, ∘ when the opening frame is in the intermediate open position, the movable wall and the fixed wall are in an arrangement that frees the ventilation passage and that allows natural ventilation between the inside and outside of the room only by said ventilation passage.