A system for measuring spirometric flow rate using a microphone and a mobile computer device connected to or integrated with the microphone. The mobile computer device may include a processor and storage. The storage may be operatively connectible, e.g over a network, to a computer system used by a practitioner. The system has a transducer adapted for converting spirometric flow rate into an audible signal with an audio frequency characteristic of the spirometric flow rate. The microphone is external to the transducer and may be adapted to detect the audible signal having an audio frequency and to convert the audible signal to a corresponding electrical signal having the audio frequency. The audio frequency may be characteristic of a peak expiratory flow rate and the output result is characteristic of the peak expiratory flow rate.
