 In addition, the modal frequencies should be verified experimentally, since it can be presumed that the frequencies of some modes deviate from their nominal values owing to the presence of the actuator with relative wave guide which has a beam width equal to 1/3 of the membrane diameter.The measurement of these deviations cannot be determined reliably with theoretical considerations, since the overall model is too complex and can only be solved (as already shown) with numerical methods.The trials carried out to date with composers and percussionists stimulated suggestions for extending the control criteria, the use of special strikers of various forms and dimensions, and the application of independent hand techniques.