A phenomenon that is paradoxical at first sight is studied: an appropriately-organized energy outflow from a resonator cavity results not in the attenuation of nonlinear vibrations but in their noticeable enhancement. An increase in the resonator Q-factor and in the energy accumulated in it is well pronounced when the frequencies of the higher harmonics generated in a nonlinear medium are close to the natural frequencies of the resonator. An important example of a nonlinear system with the necessary properties is an acoustic resonator with selective losses.

Det paradoxala beteendet att en resonators enegriinnehåll och Q-faktor kan öka när dess dämpning ökar beskrivs.