Abstract: A spirometer device includes an open ended inflatable elastomeric vessel with calibrated indicia along its length for indicating the volume of gas contained in the vessel and a mouth piece consisting of two relatively rotatable sections, one of said sections being connected to the open end of the vessel so that air can be blown through the mouth piece to inflate the vessel. The mouth piece contains a unique valving system and an air actuated sound generating device so that depending upon the relative angular relationship of the two sections, air can be blown into the vessel and retained in the vessel or allowed to escape from the vessel either through the sound generating device or not.