 The system controls the damping the skin, and therefore the decay rate of the sound, and permits isolating high frequency modes by the combined action of the nodes present on the skin and of the amount of feed-back input energy.The stability of the signal obtained with this conditioning system makes it possible to experiment and design on the skin surface a preliminary simplified map of the oscillatory modes based on the Bessel’s functions.The map is limited to 13 diameters and 8 nodal circles, the latter divided into even semicircles (to the left) and odd semicircles (to the right).