In order to calculate reasonably audible noise radiation level of capacitors

vibration pattern on the capacitor’s should be studied on.Vibration experiment on a capacitor’s case with many intensive grid measurement points are done and following features of the case are obtained: The vibration pattern at each side surface of the capacitor’s can is planar vibration.Vibration phase of side surfaces is identical and the difference between the phase of side surface and that of bottom surface is half cycle

namely

the side surface contracts while the bottom surface expends;The amplitude of vibration on the bottom surface is much higher than that on side surface.The amplitude of vibration on the side surface is basically identical.The average vibration amplitude of capacitor’s case can be used to calculate audible noise level of capacitor and the radiation ratio is one.