An overview is given of the results of simultaneous measurements of mean air flow rate, mean subglottal pressure, and sound intensity in 45 test-persons and 64 voice patients. From these values the efficiency of voice production is calculated. The measuring procedure as well as the use of data from test-persons as reference values is described. Comparing the results of voice patients with these reference values showed that the diagnostic usefulness of measuring aerodynamic data in voice production is generally low. Aerodynamic data from patients with slight adduction disturbances, however, lead to a better understanding of the pathophysiology in cases with an incomplete dorsal glottis closure and give directions to a more adequate therapy programme.