1. the prolongation and intensification of sound produced by transmission of its vibrations to a cavity, especially such a sound elicited by percussion. Decrease of resonance is called dullness; its increase, flatness. 2. a vocal sound heard on auscultation. 3. mesomerism. amphoric resonance a sound resembling that produced by blowing over the mouth of an empty bottle. nuclear magnetic resonance see nuclear magnetic resonance.