Abstract: A system for measuring the flow rate of an airflow exhaled or inhaled by a person includes a measuring apparatus and a device. The device includes a tubular pipe for guiding the airflow and a structure with a plurality of ducts configured to separate the airflow. The device further includes a first groove opening into the outer face of the wall of the tubular pipe and a component for communicating fluidically with at least one peripheral duct in the structure. A second groove, distanced from the first groove, opens into the outer face of the wall of the tubular pipe and includes a component for communicating fluidically with the at least one peripheral duct.