A computational model of human sound production based on high quality anatomic measurements and physical laws of sound propagation cannot be accomplished without a comprehensive data set including both 3D-images of the speaker's anatomy and the simultaneous recording of speech. Since the computational model has separate models for the vocal folds and the vocal tract, patients undergoing an orthognathic surgery is an optimal test object for the model development. Vocal folds remain unchanged while substantial changes take place in the vocal tract. Moreover, since the aim of the research is to predict acoustic changes in speech due to operations in head neck area, the orthognathic patient group is par excellence an example of such a prediction problem. If the model can be shown to give valuable information pre-operationally, many other patient groups could benefit from the results.