Abstract: Apparatus for monitoring oro-nasal respiration. A pair of nasal prongs, suitable for insertion into the lower portion of the nares, join together via a small plenum chamber to form a single tube conveying the nasal pressure towards an electrical pressure transducer. Another prong is held in proximity with the patient's mouth. A baffle element extends downwards from a location above the open end of the prong to redirect a portion of oral airflow. The oral tube extends towards the electrical pressure transducers and conjoins with the nasal tube at a junction to form a common tube connected to the pressure transducer. The relative lengths and/or diameters of the nasal tube and the oral tube are arranged so that the respective pneumatic impedances are different, so that the contributions of respiratory airflow from each of said tubes are substantially equal.