of the nacelles engine's surface vibration nodes and antinodes and the relative resonance dominant frequencies. At this point, setting up the measurement chain, we use the degree reduction of the phenomenon called "Sounding Board Effect"; It consists of a reinforcement or sound amplification that is directly related to structural noise irradiation. In practice, the efficiency of a sound source differs in a proportional manner directly with the ratio of its surface area and the wavelength of the produced sound. In fact, the greater the area of the radiator surface and the greater its efficiency. A sound source with a small radiant surface will produce a small air noise but will still radiate a high-frequency sound more efficiently than a low-frequency sound at the same conditions. Therefore, after attempts with the laser scanning vibrometer, the irradiated positions and dominant frequencies are identified, after which the assemblies are assembled, making them with a ridge-like plate structure, gluing (visco-elastic joints) between them the various surfaces of the plates which make them have obviously calculated areas to reduce the efficiency of the radiated sound at the frequencies of interest (obviously the low frequencies will result in the use of small radiant surfaces); It proceeds for attempts until the scanning laser vibrometer analysis shows a significant reduction in structural nodes and antinodes dominant resonance frequencies.