Abstract: The apparatus is comprised of a connection conduit comprising a mouth piece at one of its extremities, a sound generator provided with a nose, as well as a digital time measuring unit. A tapping exhaust orifice allows to tap a portion of the expired air. The orifice has an opening which is adjustable by simply turning a cuff, screwed on the outside of the conduit. When the patient expires in the apparatus, only a well defined fraction of the airflow is directed towards the sound generator, the remainder being eliminated in the atmosphere through the tapping exhaust. The airflow which remains is directed through the sound generator wherein a well defined note is produced.