Seven different performances of a fragment of W. A. Mozart's Concert for Clarinet (K622) were recorded. Each performance was inspired giving the player a sensorial type adjective in order to suggest various kinds of expressive intentions. Certain particularly significant sonological parameters were then measured. These were linked to the time factor (correlated to variations in the amplitude and duration) and frequency (variations in the timbre). The principle aim was to identify which physical parameters, and how many of them, were subject to modifications when the expressive intention of the performer was varied. The sonological analysis shows how a performer changes the physical parameters of frequency and time in function of expressive performance of a score. The evaluation of a synthesized performance, based of the values of the parameters measured, confirms the validity of the procedure.