and gsi 2 are set by the control means 22 at the values of the function u0192 2 n i finally the curve 58 represents the frequency response of the array 10 according to its last vertical operating mode m 3 when the gains gei 3 and gsi 3 are set by the control means 22 at the values of the function u0192 3 n i thanks to this two dimensional array it can be seen that it is possible to obtain either an array of resonators with wide band filtering and tunable center frequency according to m different vertical modes or an array of narrow band resonators with center frequency that can be adjusted according to m n different modes it clearly emerges that an array of resonators such as one of those described previously makes it possible to adjust with good accuracy the resonance center frequency by a simple gains setting furthermore by projecting the actuation but also the detection onto one and the same operating mode it is possible to substantially increase the amplitude of the output signal from the array of resonators since the latter is then proportional to the number of resonators thus in a use of the array as oscillator it is not necessary to provide a high gain in the reaction electrode to maintain the oscillations since the output signal is already highly amplified in the case of a large number of resonators used in the array in selective filtering type applications it is possible to envisage resonant.